# Powder Coating Tech Thread - Q&A



## LenMcC (Apr 10, 2007)

Hey guys,

Welcome to the way-more-than-you-ever-wanted-to-know-about-bicycle-finishing thread!

This is a thread dedicated to answering questions about powder coating (and other finishing techniques). I'm an avid rider and a powder coater in Virginia who shoots a lot of bikes. My intention for this thread is to answer questions and field concerns about frame material types and the effects of baking (such as on Easton scandium frames), repair options (for dents, rust pitting, etc.), about frame prep (how to ensure thin-walled frames aren't damaged during blasting, reassembly concerns), color/finish options (pearls, metal flake, textures, multi-colors, airbrushed graphics, pin striping, lug lining, clear coats, compatibility of finishes), and such.

Cheers!
Len

Here are a couple of pics of my Trance I coated the other day. Bass boat green flake with airbrushed ghost graphics. Should be finished building her up today and getting her dirty tomorrow!


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## Sasquatch (Dec 23, 2003)

That color looks close to my Retrotec's powder coat. I used Moondust Lime over a black base to get that look. I love it, although yours looks even better.


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## CharacterZero (May 19, 2004)

Looks like the Low Rider Green I have seen on some Ventanas! Love it.


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## Berkeley Mike (Jan 13, 2004)

*The single best thing you could do*

is to find or create a nice even, smooth, standard background against which to shoot your product. All you have to show is surface and color and to do that you need to eliminate distractions. The one you used in this thread is close as it is a neutral hue but the edge and the multiple tones throw off the view. Good luck.


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## LenMcC (Apr 10, 2007)

Sasquatch said:


> That color looks close to my Retrotec's powder coat. I used Moondust Lime over a black base to get that look. I love it, although yours looks even better.


Thanks! Good eye! This one is Starburst Lime. Same tone but a bigger flake size. Did Spectrum shoot your Retrotec?

Berkely Mike, thanks for the pointers on the photos! I'm a relative newb with photography, but I do try to use neutral backgrounds. Usually either black or silver slat wall. Those were quick pics. Haven't gotten to crop or adjust hues yet.


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## General Hickey (Jan 6, 2008)

LenMcC said:


>


Looks like something liberace would ride.

I like it!


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## pursuiter (May 28, 2008)

General Hickey said:


> Looks like something liberace would ride...!


Whilst good on the piano, he sucked on the organ....


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## Sasquatch (Dec 23, 2003)

LenMcC said:


> Thanks! Good eye! This one is Starburst Lime. Same tone but a bigger flake size. Did Spectrum shoot your Retrotec?


Actually, my bike was coated by Maas Bros. in Livermore, CA but I know Spectrum does most NorCal frame builder's bikes, including alot of Retotecs. I like the big flakes on yours. They stand out more.

CharacterZero, the Lowrider Green color used by Ventana is the Moondust Lime over a Black base. I was inspired by one they did a few years back, posted by an MTBR member.


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## stylie (Jan 6, 2007)

Hahahahahaha, that's one of the best one-liners I've heard in some time! :thumbsup:


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## Shredr (Sep 13, 2009)

*LenMcC*

You're right - there needs to be a sticky on this kind of stuff.

Far too many bikes, while good designs & engineered well, are poorly finished off with very little thought or creativity.

I've custom ano'ed or powdercoated all my frames & parts & I had to learn the process as I went along...& made mistakes sometimes. Trial & error can be costly.

People post all kinds of questions about powdercoating/painting/polishing/ano all over the place.Too much hit & miss on what should become an established thread...

Can you PM Francois & ask him? 
Someone with your level of knowledge & experience is needed.

I think your frame needs to be seen in person to really be appreciated- great job!


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## LenMcC (Apr 10, 2007)

Shredr said:


> People post all kinds of questions about powdercoating/painting/polishing/ano all over the place.Too much hit & miss on what should become an established thread...
> 
> Can you PM Francois & ask him?
> Someone with your level of knowledge & experience is needed.


Yeah, I got the same impression. Questions here and there, sometimes gone unanswered.

Thanks for the suggestion, Shredr! PM sent!


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## LenMcC (Apr 10, 2007)

*Easton Scandium Frames*

EASTON SCANDIUM FRAMES

Frames made from Easton Scandium, like Niners, can be powder coated with special care. Scandium frames are heat treated, and the typical PC oven temperatures (400F) is above the heat affected temperature for that process. I.e. If you put the frame through a normal cure schedule, it will likely be weakened.

Easton product engineers recommend curing for no longer than 30 min at 325. This requires a low-temp powder, which limits color options quite a bit. Make sure your coater is aware of this ahead of time to see if they're willing to make it happen.


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## LenMcC (Apr 10, 2007)

*Powder Coating Weight and Thickness*

POWDER COATING WEIGHT

Myth 1: Powder is heavier than paint.

Fact 1: Typically, powder is lighter than paint. Most liquid paints require 3 coats: 1) primer, 2) color, 3) clear. Powders typically require a single coat.

Myth 2: Powder can add 1/2 a pound to a large frame!

Fact 2: If a coater tells you the job will take 1/2lb of powder (which it shouldn't), almost all of that is ending up on the floor as overspray. Typical weights I've measured myself are around 1oz per coat for a large hardtail. Most liquid painted frames from the factory lose around 2oz after stripping. I'll post up some hard numbers for factory painted, stripped, and coated weights for various frames.

POWDER COATING THICKNESS

Myth 3: PC is thick.

Fact 3: PC, when applied properly, is very thin. Generally it is applied around 0.003" - or 3 mils. Many people are familiar with lawn furnature PC that has super-thick, often textured finishes. These finishes are applied using a completely different method, with the intention of hiding surface imperections of the relatively low-quality fabrication and preparation processes. If you have a lugged frame with nice detail work, you're not going to lose any of that detail with a proper coating. Conversely, if you have a beat up frame, don't expect a single coat of powder to fill the defects.

Myth 4: Thicker is stronger.

Fact 4: Thinner is stronger. With most powders, it just works out that way. Thinner coatings (applied at the proper thickness, rather than hogged on), are much more chip-resistant than heavy coats. They're much smoother, too.


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## D.F.L. (Jan 3, 2004)

What are the benefits of powder coat primer, esp as it pertains to rust prevention on steel frames? Can you still do multi-coat powder colors over a primer coat? (I understand that the static attraction is diminished with each successive coat)

Tell us more about the graphic-in-powder process. I sent a frame to Spectrum for a 'full-powder' job, but received a bike with a powder base, and wet paint panel and clear... not what I was hoping for. I know that there are high-temp decals that can survive beneath powder clearcoat, but what is the process for airbrushed graphics with clear? Is there a high-temp-tolerant paint that can survive the baking process and live beneath a powder clear topcoat? I guess I would expect that any graphics placed atop the base coat and beneath the clear would become 'blurred' as the powder melts into place.

Thanks!


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## LenMcC (Apr 10, 2007)

*Powder Primer and Clear Powder Over Graphics*

Great questions...

POWDER PRIMERS
There are a few types of powder primers.

1) Zinc Primer: 
The rust-prevention type is a zinc primer. It reduces steel oxidation because the zinc is more reactive than steel, so the zinc gets oxidized first. Same concept as galvanization. Zinc primers are primarily used on items that are kept in the elements and are subject to abuse, like fences and gates. For bicycles, it's not particularly helpful as long as the frame is prepped properly, which means the metal is "white blasted" immediately prior to coating (super-clean and free from all oxidation). Many coaters do not white blast their pieces.

2) Filler Primer:
Filler primers are more like liquid paint primers. The primary goal of these are to give the frame a nice smooth surface prior to the color coat. These are great for filling small scratches and rust pits. For heavy pitting, deep gouges, and dents, a special conductive, high-temp bondo-type body filler can be used.

3) Powder Primer Under Wet Paint:
Another use for either of those primers is as a base for wet paint. This can increase wet paint adhesion compared to conventional liquid primers.

Yes, you can still do multiple coats with primer. Powder guns are getting better and better, and combined with some application skill, it's perfectly feasible to do 5 or more coats. It's even possible to coat non-conductive items (like porcelin toilets) with the right techniques.

FULL-POWDER GRAPHICS
1) Airbrushed:
Full-powder graphics is something only a few coaters have figured out. Spectrum was a pioneer with it. The basic process is: 1) shoot the base coat and do a partial cure, 2) airbrush the graphics with a special pigment, 3) apply the clear powder top coat and final cure. During the final cure, the clear top coat will cross-link (basically melt) through the graphics pigment into the partially-cured base coat, making all three layers one.

That being said, there are some limitations to full-powder graphics. A notorious limitation is white graphics on a red base. During the final cure, the red pigment in the base coat will sublimate (vaporize) into the white, turning it pink. I haven't figured out a work-around, and I don't think Spectrum has, either. In a case like this, the top coat would need to be liquid. Here is a picture of white-on-red. You can see how it turned pink.










The resolution of airbrushed graphics is just like wet paint; there is no blur. Here are some pics of clear powders over airbrushed graphics. Clears come in high-gloss, matte, and in-between.





































2) Decals:
Yes, there are hi-temp decals meant for use under powder. The only company I'm aware of that makes these are SSS, Inc. in North Carolina. I haven't dealt with them myself, but I know some frame builders get their decals from them and provide them to the coater (I believe Strong does this). SSS, Inc. has supposedly figured out how to avoid the sublimation problem with reds and blacks. Water slide decals still need to be liquid cleared.


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## Shredr (Sep 13, 2009)

*LenMcC*

Great posts & excellent info! A few questions:

Is this always the normal operating procedure for powdercoat? 1) Base first, 2) Then Powdercoat in oven, 3) Then spray Clearcoat?

Should I tell the painter what series alloy my frame is made out of before putting in the oven?

If the alloy frame is machine polished first, can you skip the base step or not? I always go for bright, shiny, flashy showroom-quality colors that really stand out & "glow".

Also, what if I want to do a type of 2 tone paint color fade job? (like red to black to red)?
Is it possible with powdercoat?

Finally, If I bring a Chris King hub (sour apple color ano) & ask for an exact match with powdercoat is it possible or asking for too much?

Thanks LenMcC!


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## LenMcC (Apr 10, 2007)

Always glad to help!



Shredr said:


> Great posts & excellent info! A few questions:
> 
> Is this always the normal operating procedure for powdercoat? 1) Base first, 2) Then Powdercoat in oven, 3) Then spray Clearcoat? Most powders are done in one shot. The powder is applied, the frame goes into the oven, and the powder flows out into a smooth finish. Multi-coats may be required to get a certain look (e.g. that heavy green flake Trance... The green flake is suspended in a clear powder, so you see what's underneath, in that case black), to change the gloss, to protect graphics, or to protect metallics that use aluminum flake (to keep the aluminum from dulling).
> 
> ...


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## rallyraid (Jun 12, 2007)

Thanks for starting the thread LenMcC. Is it a good idea to powder coat a bike in wrinkle finish? Is dirt going to stick in the crevices, making it always dirty?


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## LenMcC (Apr 10, 2007)

rallyraid said:


> Is it a good idea to powder coat a bike in wrinkle finish? Is dirt going to stick in the crevices, making it always dirty?


Textures (wrinkles, veins, hammertones, leatherettes, rivers, casts) are great for economically hiding imperfections. So for frames that are heavily rust pitted, or naturally rough cast pieces like many valve covers, the textures are popular.

How much they collect dirt depends a lot on the type of texture. Textures will always take a little more elbow grease to clean than gloss or glaze tones (scrubbing with a brush instead of a sponge), but some textures would be cleaning suicide. "Cast" textures, for example, have an almost sandpaper-like texture, and would trap dirt like crazy. The rough textures are typically meant for indoor use (and some aren't UV stable, so they'd fail in the sun). A good coater should be able to tell you some low-maintenance options AND show you a chip so you can see it, touch it, and make a good decision.


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## Shredr (Sep 13, 2009)

*LenMcC*

An observation:
It seems like these days (with all our great technology) we're only limited by our imagination when it comes to custom paint jobs & tinkering with the finish on parts as well.

A suggestion:
Can you find a link to a good site with high-quality pics of custom painted frames?
Or perhaps put something together like a gallery?

You can point out good paint jobs & poor ones...& help point out the differences between spray jobs, powdercoat & ano.

I think artists are inspired by other artists. It helps to see others custom work.
I'm learning a lot from this thread.


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## LenMcC (Apr 10, 2007)

Yeah, if you can dream it, someone can figure out how to do it.

When it comes to good jobs vs. bad, sometimes it's hard to tell, particularly if the finish is basic (single color without graphics). Two invisible but extremely important parts of the job is 1) how well the piece is prepped, and 2) how closely the cure schedule of the powder is followed.

1) It's extremely easy to do a bad job prepping, or leave it out altogether. And the customer will never know, til a while down the road when the coating fails and starts to chip. When powder chips, the exposed metal is usually pretty shiny, which means it wasn't prepped. The metal should be abrasive blasted to give it an "anchor profile", more commonly known as "tooth". The slightly rough finish left by blasting increases surface area and gives the powder a surface it can really grab. Alternatively, some coaters OVER-blast pieces in the name of speed, which can leave the finish rough - or worse - damage the frame (some people have experienced this in the form of holes blown through thin-walled aluminum tubing).

2) Powders have different chemical formulations, and each of them has a specific cure schedule. Most cure around 400F for 12-15 minutes *after* the part reaches the cure temp. For optimal durability, the part temperature and cure time need to be carefully monitored. Many coaters have large batch ovens that they bake a bunch of parts in at once, and use a guess or an average cure temp/time. Even though the finish will look fine, it won't be as tough as it should be. An under-cured finish finish will scratch easily and adhesion will also be reduced.

If someone quotes you a price that is far less than the good guys, there's probably a reason for it.










More obvious indications of bad jobs are just plain poor finish quality and poor or completely missed masking of threads, bores, and bosses. A good bicycle coater will know to keep the head tube faces clean, and will probably ask if you'll be running an internal or external BB so they know whether to keep the BB faces clean, as well. A lot of the quality here comes from the coater's familiarity with the parts.

The difference in appearance between wet paint and powder, when done properly, are not obvious. Both should be seamless and high-gloss. And sometimes, they're used in combination making it even more difficult to distinguish (powder base with a candy or clear wet coat).

Some pretty skilled bicycle powder coaters are:
Spectrum Powder Works - www.SpectrumPowderworks.com
Figure Finishing - www.FigureEngineering.com

Wet paint finishers:
Keith Anderson Cycles - www.KeithAndersonCycles.com
Cyclart - www.Cyclart.com


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## John Kuhl (Dec 10, 2007)

LenMcC, I just want to say thanks. This is very
interesting info, and I'm learning a lot.

Best, John


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## Apex (Mar 6, 2005)

Len if I used water slide decals and liquid cleared over them would the powercoat need to be lightly sanded for the clear to stick or not?


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## Shredr (Sep 13, 2009)

*LenMcC*

Thanks for those great links. Lots of good pics...
Another question: Considering tubing size & shape when choosing a paint scheme:

Will this type of paint job will look good on a Alum.Titus El Guapo?
I always try to match my colors & designs to bring out the bikes specific tube shapes.

In other words, that paint job seems to flow with the unique shape, size & angles of the roadie (carbon) tubing. I think it's BOTH the tubing shape/angles AND the nice paint that works together here. So, would that type of 2-3 color paint design transfer over to a frame with different shaped tubing (alum.) or not?

It seems to me that different shaped bike tubing (from small tubed chro.mo to fat tube alum.) creates completely different effects when custom painted? I've seen many custom painted chro.mo. frames with tiny tubing & those jobs don't really "pop" out like large tubed alum. frames (less surface area?).

So, shouldn't the size & shape of the frame tubing be an important factor to consider when picking a paint design? Any tips in this area?


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## runjhike (Aug 24, 2008)

I'm curious about how powder coating affects my warranty. I have an 09 Trek Remedy that I want to be flat black. I heard stripping it to the bare aluminum or painting will void the frame's lifetime warranty. Is that true/common? Thanks. Great info here.


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## blue109 (Jun 21, 2009)

if you have an anodized part, do you need to strip/prep it before you PC it? will sandblasting or light sanding take off the ano layer?


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## Apex (Mar 6, 2005)

runjhike said:


> I'm curious about how powder coating affects my warranty. I have an 09 Trek Remedy that I want to be flat black. I heard stripping it to the bare aluminum or painting will void the frame's lifetime warranty. Is that true/common? Thanks. Great info here.


Email their warranty dept and they will tell you how to paint the bike to keep the warranty. I emailed them previously and was told that as long as its NOT sand blasted and that you document (with pics) the stripping/painting process the warranty is fine. You can bead blast it and its OK.


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## LenMcC (Apr 10, 2007)

Apex said:


> Len if I used water slide decals and liquid cleared over them would the powercoat need to be lightly sanded for the clear to stick or not?


Yes, for best adhesion, the whole frame should be scuffed with grey scotchbrite. *BUT* if the finish is a metallic that doesn't have a powder clear on it, scuffing will damage the metallic.


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## LenMcC (Apr 10, 2007)

Shredr said:


> Thanks for those great links. Lots of good pics...
> Another question: Considering tubing size & shape when choosing a paint scheme:
> 
> Will this type of paint job will look good on a Alum.Titus El Guapo?
> ...


Yes, you're on the right track with design considerations. Generally, the smaller the canvas, the simpler you want to keep the design. The frames with bigger tubes and interesting geometries give you more options for really outstanding paint work. The carbons look really sexy with the kind of design in your pic since all the transitions between tubes are smooth. Generally on welded frames (with the exception of frames like Cannondales with smoothed welds), it's best to avoid lines flowing from one tube to the next across a weld. When you try to do that, the clean look of the line is interupted by the weld, and it usually doesn't look right. It goes right back to what you were talking about... working with the shape of the frame and not against it. Look at lots of pics of nicely painted welded frames, and you'll see that usually the head tube color will carry onto the top and down tubes, and then that color will move into the rest of the design.


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## LenMcC (Apr 10, 2007)

runjhike said:


> I'm curious about how powder coating affects my warranty. I have an 09 Trek Remedy that I want to be flat black. I heard stripping it to the bare aluminum or painting will void the frame's lifetime warranty. Is that true/common? Thanks. Great info here.


Like Apex said, it's best to talk directely to the manufacturer to find out how refinishing can affect the warranty. When a customer expresses concern over it, I pick up the phone and call one the mfg engineers, and they're happy to help.

That being said, I'd expect that pretty much any modification to just about any product would void the warranty (unless, like Trek, they will honor documentation of specific procedures). It just makes sense from the manufacturer's standpoint. Any reason not to have to give a customer a free replacement is a good one. And like I mentioned before, frames can be damaged by careless blasting (hence Trek's "no blasting" policy) or someone just not knowledgable about bicycles, so the mfg really shouldn't have to honor the warranty in those cases.

Some mfgs may allow finishers to become authorized refinishers, thereby automatically maintaining the warranty. The only one I've checked into at this point is Speciallized, and the guy I talked to said that no one in the USA is an authorized refinisher, but he gave me the number of someone else to talk to that I haven't contacted yet.


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## Shredr (Sep 13, 2009)

*LenMcC*

Len, your advice is saving me from making design mistakes!

Great thread!


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## LenMcC (Apr 10, 2007)

blue109 said:


> if you have an anodized part, do you need to strip/prep it before you PC it? will sandblasting or light sanding take off the ano layer?


This is an excellent question that comes up a lot... Powder actually adheres very well to ano. For some products, anodizing is actually specified by product engineers as a pre-treatment for PC as an alternative to blasting. We abrasive blast our parts before PC, though, which removes the ano layer and leaves fresh, clean, uniform, slightly rough metal for maximum adhesion and to ensure the ano color doesn't affect the power color.


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## Bikeeveryday (Jan 10, 2005)

Will powdercoating a fork jeopardize its integrity? Magnesium Lowers, aluminum crown. Baked at 400 degrees.


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## LenMcC (Apr 10, 2007)

*Magnesium Powder Coating*



Bikeeveryday said:


> Will powdercoating a fork jeopardize its integrity? Magnesium Lowers, aluminum crown. Baked at 400 degrees.


There is more misinformation out there about PCing magnesium than just about anything else. I have no experience with it, but I called the Powder Coating Institute, and the technical director should be getting back with me today with some real answers.

Things I know to be true: 1) Extreme care must be taken with stripping. Most chemical strippers eat mag like crazy and will ruin the part. 2) Magnesium has a tendency to outgas during cure (the material is porous, and air trapped in the pores will escape during baking and cause lots of tiny bubbles in the finish). 3) It has been successfully PCed by many coaters, and often comes that way from the factory.

Things I know to be false: 1) Magnesium will catch on fire in the oven.

Things I'm unsure about: 1) I've read that magnesium strength can be weakened by PC temps. I've also read that mag is typically heat-treated (if at all) at 500F, and that it can safely be baked at 450 without any affect on strength. 2) Magnesium becomes dimensionally unstable at 350F. It's melting point is around 1200F, I believe, and if it's heat-treated at 500, this would clearly be false. 3) Magnesium oxidizes quickly (true), and it's typically "pickled" (chemically treated) from the factory, so abrasive stripping that leaves the magnesium bare (without re-pickling) will allow it to oxidize quickly if the coating is ever damaged exposing bare mag, which in turn will cause the coating to fail in the area surrounding the damage.

I'll post up the answers as soon as I get them.


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## LenMcC (Apr 10, 2007)

Ok, I just talked to Roger at the Powder Coating Institute, and he was kind enough to impart some magnesium knowledge.

Turns out most of the information out there about coating mag is a myth.

Here are the noteworthy things about it:
1) Most chemical strippers attack it violently; it should be stripped mechanically (sanding or blasting).
2) Blasting (carefully at reduced pressure) is the preffered method of stripping.
3) Magnesium is very porous (hence its super-light-weight), and therefore is prone to outgassing (tiny bubbles in the finish). To combat this A) the part should be prebaked prior to coating at 450F, B) cured at a reduced temperature for a longer cure cycle (e.g. 350 for 30min vs. 400 for 15min), and C) may need a second coat.
4) Since mag is so porous, powder adheres to it VERY well. Bare mag does not need to be re-pickled.
5) Dimensional stability (warping) is only a concern if the wall thickness is less than 0.060". For thin-wall pieces, special consideration is necessary for how the part is hung during baking so it doesn't deform under it's own weight.

Item 3 will increase the coating cost, due to added time and labor. Item 1 may also increase cost if the mag was PCed from the factory, since most chemical powder strippers eat mag, and blasting really doesn't work on PC, except with a special plastic abrasive (this plastic abrasive would be safe on the mag).


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## Bikeeveryday (Jan 10, 2005)

got mine sand blasted.


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## kneecap (Dec 20, 2003)

Probably a no brainer, I see you removed the headset bearings & bottom bracket on your trance, did you, or is it necessary to remove the rear triangle pivot bearings for powder coating?


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## LenMcC (Apr 10, 2007)

*Bearings, BB, Headset Races, etc.*



kneecap said:


> Probably a no brainer, I see you removed the headset bearings & bottom bracket on your trance, did you, or is it necessary to remove the rear triangle pivot bearings for powder coating?


Yes, you want to remove everything for powder coating. Bearings would get smoked in the oven, and the head races would likely be contaminated. Most coaters who are good with bikes have the tools to remove that stuff and will do it for free or cheap.


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## LenMcC (Apr 10, 2007)

*Carbon Fiber and Coating Non-conductive Materials*

These are some questions I stumbled across in other threads:

Q: Can carbon fiber be PCed?
A: Carbon has been successfully PCed. BUT, it depends on the resin matrix. The only way I know of to figure out if it can take the heat (without knowledge of history for a particular carbon) is to bake it, and if it can't take the heat, you're out a pricey frame or part. Stripping is another issue. Even if the carbon could take the heat, the paint that's on it probably won't, and there's no real good way to strip the paint from carbon. Bad idea to chemically strip or blast, so you're left with hand sanding, which isn't going to get it perfectly clean. I won't coat CF, it's wet paint all the way.

Q: Does the material being coated have to be electrically conductive?
A: No. The conventional method is to electrically ground the substrate (requiring conductivity), and the powder gun charges the powder making it stick to the part as the charged particles try to reach ground. Special application systems and application techniques can bypass the necessity for grounding.


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## LenMcC (Apr 10, 2007)

*Sand Blasting... Media Blasting... Is it safe?*

Q: Is media blasting safer than sand blasting on my frame?

A(media vs sand): Before talking safety, we need to clear up the lingo... The term "sand blasting" really just means "abrasive blasting". "Media blasting" also means the same.

Sand was used extensively back in the day because it was cheap and readily available, but it sucks. The quality of the blast profile is poor, it's not particularly aggressive (requiring higher pressures to get any "cutting" action... kinda like a "dull knife is a dangerous knife" type thing), it's dusty, and that dust causes silicosis (chronic fibrosis of the lungs)...

There are tons of types of medias: sand, coal slag, aluminum oxide, silicon carbide, steel shot, plastics, walnut shell, glass bead, crushed glass, baking soda, dry ice... When a coater refers to "media blasting" or "sand blasting" or "bead blasting" or just "blasting" they're typically all the same.

A(safety): Can blasting destroy a frame? YES! Can blasting be done safely? YES! The combination of media selection, air pressure, air volume, gun nozzle type, and gun angle all play roles in safety and determine whether damage will be done.

Many coaters' primary method of stripping a part is to blast the heck out of it as quickly as possible, wham bam done. This means super-aggressive media at high pressure. Those two things are not friends to thin-walled aluminum bicycle frames, and indeed, holes have been blown in them. The proper way to prep a frame is to 1) chemically strip the existing paint or powder, 2) rinse and clean the frame, 3) give it a *light* blast. The purpose of blasting (properly done) is NOT to strip the metal, but rather for final cleaning (eat off it clean) and to condition the metal. The conditioning leaves the metal *slightly* rough (called an "anchor profile"), which greatly increases powder (or paint) adhesion. The goal is to NOT remove metal (unless it's a 1960's Schwinn that looks like it's been at the bottom of a lake for decades). Done properly, you should have NO concerns about blasting affecting the integrity of your frame.

Bonus Fact: Blasting things can actually make them stronger. Blasting with steel shot (known as "shot peening" or just "peening") introduces compressive stresses on the surface of the metal increasing the metal's fatigue life. Again, the goal here is not to remove metal, just to kind of smash it into itself to make the surface denser.


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## gsy971 (Jan 14, 2005)

LenMcC, i have been reading along and still am need of a more "professional" opinion, Here is my thread i started on possible PCing my Klein Adept
http://forums.mtbr.com/showthread.php?t=304237


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## LenMcC (Apr 10, 2007)

gsy971 said:


> LenMcC, i have been reading along and still am need of a more "professional" opinion, Here is my thread i started on possible PCing my Klein Adept
> http://forums.mtbr.com/showthread.php?t=304237


reply posted!


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## hankthespacecowboy (Jun 10, 2004)

Thanks for this info! I've had two frames powder coated and haven't been thrilled w/ the results. The first in particular, was horrible. I could have done a better job with a can of Krylon and a six pack of PBR. Looks like you've got a great handle on the process though!


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## archer (May 20, 2004)

Shot peening is very dependant on the operator.

It is used to close pores in the metal and increase fatigue life in aluminum aircraft parts but studies have shown that it is sort of an art that with the wrong operator can be useless or even damaging.


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## LenMcC (Apr 10, 2007)

archer said:


> Shot peening is very dependant on the operator.
> 
> It is used to close pores in the metal and increase fatigue life in aluminum aircraft parts but studies have shown that it is sort of an art that with the wrong operator can be useless or even damaging.


absolutely. wikipedia has an interesting article about it (don't know much about it myself). it says it can increase fatigue life by 0% to 1000%. also says the benefits are lost if the part ever reaches annealing temperatures, which makes sense.

i used to work at a a heavy manufacturing facility, and they were installing a giant cnc mill that sat on a 6" thick piece of steel plate. they had to weld the sections of plate together (starting out with one plate at about a -45deg angle... the plate would draw up flat as the beads were laid), and periodically they would jack hammer the beads to relieve the residual stresses. ...talk about an art. very cool stuff.


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## CanOnlyRide (Oct 27, 2005)

Regarding the white graphics over red. Wouldnt you do the red, then clear it and then to the white and then clear again?


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## LenMcC (Apr 10, 2007)

CanOnlyRide said:


> Regarding the white graphics over red. Wouldnt you do the red, then clear it and then to the white and then clear again?


Excellent thought! An inter-clear helps, but the red still sublimates through it. One of the great things about powder is that when you bake subsequent coats, they crosslink (or melt) into each other making it one layer. Normally it's a great thing, but it causes problems with color bleed in this case. I'm sure there's a solution, I just haven't found it yet.


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## LyNx (Oct 26, 2004)

Great thread, thanks for taking the time to share your knowledge. Wanted to subscribe to the thread as well as share a couple pics of the Specutrum work - they do truly amazing work.


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## LenMcC (Apr 10, 2007)

that bike is pure sex. i dig the spokes.


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## themanmonkey (Nov 1, 2005)

CanOnlyRide said:


> Regarding the white graphics over red. Wouldnt you do the red, then clear it and then to the white and then clear again?


FYI I'm going from 10 years ago when I used to powdercoat bikes, so I could be a little outdated.

Anyway, the problem you get into something like that with so many layers is all the partial coats mean that you're getting full cure on the lower layers when the tops are still very wet. Then also you would be over curing the bottom layers to get the top layers right. I was taught no more than 3 layers because the bond between the layers wouldn't be very good.

The new powders may have better range than the old ones. We used Spectrum and Tiger powders back then.


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## LenMcC (Apr 10, 2007)

themanmonkey said:


> FYI I'm going from 10 years ago when I used to powdercoat bikes, so I could be a little outdated.
> 
> Anyway, the problem you get into something like that with so many layers is all the partial coats mean that you're getting full cure on the lower layers when the tops are still very wet. Then also you would be over curing the bottom layers to get the top layers right. I was taught no more than 3 layers because the bond between the layers wouldn't be very good.
> 
> The new powders may have better range than the old ones. We used Spectrum and Tiger powders back then.


This is still true to a certain extent. Most powders have a high tolerance to over-baking. The worst thing that usually happens is they lose gloss, but that's not a problem with susequent coats. Always better to over-cure than under-cure. Light colors and clears can yellow if over-baked. To combat this, base coats are partially-cured at a lower temperature for a shorter time for the purpose of getting them to "flow out". Once all the coats are applied, the piece is baked at full temperature for the full bake cycle and all coats undergo the final cure together.


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## Yogii (Jun 5, 2008)

GREAT POST! LenMcC thanks for all the great info!
Just a few questions please:
Are pearl and/or candy colors much harder to produce? I know these are two step processes, I guess three if you count the clear. My framebuilder's PC guy was not sure he could do them.
Is the a difference, visual or otherwise, between a base coat with glitter and then a clear or a plain base coat with glitter in the clear?
I know two-tone red and white is a no no. What about white and blue? or Chrome(PC) and red? Do you find that many people ask for chrome PC? MUCH more enviro-friendly than real chrome.

Thanks again.


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## LenMcC (Apr 10, 2007)

Yogii said:


> GREAT POST! LenMcC thanks for all the great info!
> Just a few questions please:
> Are pearl and/or candy colors much harder to produce? I know these are two step processes, I guess three if you count the clear. My framebuilder's PC guy was not sure he could do them.
> Is the a difference, visual or otherwise, between a base coat with glitter and then a clear or a plain base coat with glitter in the clear?
> ...


Glad to help!

This is kind of a can of worms digging into this stuff... There are endless possibilities as far as different looks go. A lot of pearls and metallics are single-stage (single coat), so they don't need a clear or top coat, but clears really make them pop. Pearls are typically single-stage, but don't tend to be glossy, so a clear is nice. Candies are just a tinted clear, so you see whatever is under them. They look phenominal over real chrome plating, polished/brushed/swirled/grinded aluminum, or over a metallic silver.

As far as "glitter in the base" goes... Metallic flake isn't usually added to a plain powder. the powder comes that way, and it's called a "bonded metallic", because the flake is chemically attached to the powder particles. This does two important things: 1) it keeps the flake evenly distributed in the powder, and 2) it keeps the flake from standing up on it's side during application. Nonuniform distribution and flake stand are both caused by the static charge (imagine little bits of styrofoam on a plastic comb, or someone with their hand on a Van der Graff generator and their hair standing up.) Non-bonded powders are when flake is added to a powder after manufacturing. It can still be a cool look, but you lose a lot of the flake look in an opaque base. A lot of metallics or flakes are suspended in a clear powder, so you see whatever is underneath. They're usually shot over black, so the black absorbs light, and you just get the "pop" off the metallic (like my green Trance in my first post). Then there are clears with just a little bit of flake, so it looks like the piece was lightly "dusted", just getting a few pops at any viewing angle. Metallics that are aluminum-based require a clear. Plastic-based flakes do not (like the Trance, the metallic coat IS the clear coat).

White-over-black, white-over-blue both work fine in my experience.

I don't do a lot of chrome PC. I don't recommend it to customers, because I don't like the look of it. It's not fooling anyone. If you see a pic of "powder chrome" that looks impressive, it's probably because 1) the lighting and camera angles were just right, and more importantly 2) it probably wan't cleared yet. Chrome PCs typically need a clear, because they gain their look from super-fine aluminum flake, and without a clear they're delicate and oxidize fast. Clear turns them more grey and kills shine. One ok use for chrome PC is under a candy, if real chrome or polished aluminum isn't an option.

Just like any chemical process, hexavalent chrome plating can be done in such a way that it doesn't destroy the environment or the people plating. Old timers killed it for most places. ...between sloppy practices (spills, improper disposal of highly toxic chemicals) and just plain stupid practices (they used to dip their finger in the tanks and taste their finger to tell when to add chemicals!!) :eekster:


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## Beaker13 (Feb 10, 2009)

Great thread LenMc:

I just took my Niner Rip9 in to be pc'd. Love the bike - hate the dull ano silver. Sure hope I like the Green metallic "moss" and black metallic rear triangle better. Will post pics in about a week when my baby returns. BTW - all my riding buddies and wife think I'm stupid and wasting my money (about $75).

With that being said, why should I not love everything about my bike? I plan on riding this bike for another 5 years or so when I can possibly justify another $4k on a new bike. 

Also - with so many colors available and PC being relatively easy, why don't more manufacturers (smaller ones) offer your own custom PC options?


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## LenMcC (Apr 10, 2007)

Just a heads up, but to the best of my knowledge (someone please correct me if you know different) all the Niners are made with Easton scandium tubing, and aren't supposed to be exposed to more than 250 (I think) degrees, or it can affect the heat treatment of the tubing. I don't know if or how much PC temps will affect strength, just that the Easton engineer I talked to recommended not PCing it with conventional (non-low-temp) PC. Be sure to give your frame a good inspection regularly throughout it's life.

$75 is insanely inexpensive. I'm not sure how they can pull that off.

I imagine the lack of custom PC out of the box is a cost thing. Most builders probably aren't trying to double the price of their frames with one-off paint jobs, though I know that true custom builders do offer whatever finish the customer wants and is willing to cover.


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## Beaker13 (Feb 10, 2009)

The RIP9 and WFO are both aluminum for sure, the Air9 is the only one I know for sure to be Sc, the SIR is steel.

It is a one coat, no fade, plus clear top coat job. I had 3 options (that I could find) in this area, 2 were under $100 and the third was about $150-$200. That is the price assuming they had the color(s) in stock that I wanted. Add about $200 if they had to order a color in for me.


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## LyNx (Oct 26, 2004)

You sir stand corrected  LOL  They are actually not Easton Scandium but just either 7005 or 6005 based alu. I asked this question long ago about PCing my earlier RIp9 frame and was told to keep it under 400F and everything would be fine.

To Beaker, here's a serious warning......the tubing on those frame isn't very thick, I WOULDN'T trust media blasting on it, I'd make sure it was stripped using a liquid paint stripper and then lightly blasted to get the adhession necessary for PC.



LenMcC said:


> Just a heads up, but to the best of my knowledge_* (someone please correct me if you know different)*_ all the Niners are made with Easton scandium tubing, and aren't supposed to be exposed to more than 250 (I think) degrees, or it can affect the heat treatment of the tubing. I don't know if or how much PC temps will affect strength, just that the Easton engineer I talked to recommended not PCing it with conventional (non-low-temp) PC. Be sure to give your frame a good inspection regularly throughout it's life.
> 
> $75 is insanely inexpensive. I'm not sure how they can pull that off.
> 
> I imagine the lack of custom PC out of the box is a cost thing. Most builders probably aren't trying to double the price of their frames with one-off paint jobs, though I know that true custom builders do offer whatever finish the customer wants and is willing to cover.


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## LenMcC (Apr 10, 2007)

LyNx said:


> You sir stand corrected  LOL


That's good! I'm glad to learn from this thread, too! Thanks for the good info on the Niners!


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## LyNx (Oct 26, 2004)

Glad I could provide a smidge of info to this wonderful thread  I pointed my loca PCer to this thread, so we'll see what he says next time I pass by :thumbsup: he was very interested to read it.



LenMcC said:


> That's good! I'm glad to learn from this thread, too! Thanks for the good info on the Niners!


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## LenMcC (Apr 10, 2007)

cool. who's your local coater? i'm pretty active on a few PC forums... maybe I know him from one of those.



LyNx said:


> Glad I could provide a smidge of info to this wonderful thread  I pointed my loca PCer to this thread, so we'll see what he says next time I pass by :thumbsup: he was very interested to read it.


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## LyNx (Oct 26, 2004)

Local, as in on the island of Barbados  Kinda doubt you'd know him. I did talk to him yesterday and he said he'd browsed the thread and found it interesting, but hadn't had a chance to get back and do a more thorough read.

Some time in the not too distant future I hope to take the time and get some paint stripper and strip the frames I want done, but most likely won't happen until summer.



LenMcC said:


> cool. who's your local coater? i'm pretty active on a few PC forums... maybe I know him from one of those.


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## Crankenator (Mar 27, 2007)

Len...if you aren't tired of fielding questions yet.  

You mentioned a little about curing a couple times. I'm curious as to what an undercured coating would feel like, say, like a fingernail test. Is it only a matter of flow and surface finish, or is undercured coating soft? Flaky? Also, can undercured parts be re-cured by a second bake? 

And one more....best way to remove a thicker coating that wasn't properly masked before spraying? I helped a friend of mine get some pedals/rims/hubs/stem coated last summer and they obviously weren't that experienced with bike parts. Had to remove the PC on the rotor mount surfaces and it was a pita. Tough finish and it was bonded well, I'll say that for it! 

Thanks again for sharing all of this with us!!!


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## Crankenator (Mar 27, 2007)

oh....also. 

Baking soda as a media??? Dry ice, too? Got a brief 101 brochure on when and how those are used? I thought I knew a little about blasting but I've never heard of those two. Very interesting.


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## LenMcC (Apr 10, 2007)

*Under-cured PC & Selective Removal of PC*



Crankenator said:


> Len...if you aren't tired of fielding questions yet.
> 
> You mentioned a little about curing a couple times. I'm curious as to what an undercured coating would feel like, say, like a fingernail test. Is it only a matter of flow and surface finish, or is undercured coating soft? Flaky? Also, can undercured parts be re-cured by a second bake?
> 
> ...


You're welcome, always glad to help!

Under-cured coatings are not apparent just by looking at them. I don't know what a finger nail would do to it, but it's definitely apparent when installing components or using it, because it will scratch surprisingly easy. I think the chip-resistance is similar to conventional paint at this point. Partially cured PC is very brittle, and it becomes more flexible as it cures. Yes, re-baking will complete the cure.

Best way to remove the finish is with sand paper, or maybe very carefully with a sanding drum on a dremel, depending on where you're trying to remove it. A lot of times a file is a lot faster and can get into corners well. A good trick is to put tape on the good area around the area you're trying to knock down. That way, if your hand slips, the abrasive is hitting tape instead of the finish. It generally takes a lot of patience.


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## LenMcC (Apr 10, 2007)

*Non-conventional Blasting Medias (Soda and Dry Ice)*



Crankenator said:


> oh....also.
> 
> Baking soda as a media??? Dry ice, too? Got a brief 101 brochure on when and how those are used? I thought I knew a little about blasting but I've never heard of those two. Very interesting.


Yeah, crazy, huh? I've never used either, so I'm regurgitating what I've read...

Both of those are good for blasting old car bodies. If you blast sheet metal with regular media, it will warp beyond repair unless you're really care and observe a bunch of rules about blasting sheet metal. The impact of media on the metal surface compresses the surface of the metal creating a residual stress in the metal that makes it warp out of shape. Soda has two big advantages here: 1) it's very light weight and relatively soft compared to conventional media, so it doesn't create the surface stresses and warp. 2) Since it's not removing metal, you don't have to mask off delicate areas of the car, like windows, rubber trim, plastic, etc. It's safe to use on all that stuff and even fiberglass. I know less about dry ice, particularly regarding performance, but I think its main advantage is that there is no mess to clean up since it evaporates. I could see that coming in very handy in a car interior, or perhaps blasting internal engine components where leftover sand-type medias would blow the engine (typically walnut shell or corncob medias are used for engine stuff for this reason).


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## Crankenator (Mar 27, 2007)

Gracias, sir! This really is an invaluable thread.


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## powdercoater (Apr 10, 2010)

LenMcC, for powder coating over reds try over curing the red, twice as long. I have good success with Tiger's dormant colours over curing, to stop the bleeding after clear coating. Charcoal metallic flames over dormant violet. The flames only come out in bright light. (sunshine)


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## LenMcC (Apr 10, 2007)

powdercoater said:


> LenMcC, for powder coating over reds try over curing the red, twice as long. I have good success with Tiger's dormant colours over curing, to stop the bleeding after clear coating. Charcoal metallic flames over dormant violet. The flames only come out in bright light. (sunshine)


haven't tried it with a dormant red. makes sense that it could work though, since it doesn't turn red til it's cleared. what's it look like before clear? do you have to use a specific tiger clear?


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## powdercoater (Apr 10, 2010)

It sorta looks like chrome with a tint of violet. The clear coat I was using at that time was Miller's 2 mil clear coat. Also worked great applying white over the dormant, then clear coating the whole bike frame, without bleeding into the white.


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## josephr (Apr 7, 2010)

I'm glad I found this thread! I have a Kona 4 with a scandium frame that I'd like to paint and was thinking a powdercoat would be more durable in the long run. The local PC companies I've found mostly do racecars and have only done the occasional bike, but none had even heard of Sc --- probably would've eaten a hole when they bead blasted it and, if not that, probably would've weakened the frame I'd have a cracked chainstay from the first rock garden!

Ok -- maybe I'm over-reacting....still, nice to know that just a regular ole PC isn't the way to go. I saw where you suggested two PC companies out west, but also saw where you said you know a few other PCers. I live in Birmingham, AL and currently on project in South Carolina .... can you reccomend any PCers in the area (Atlanta is good too) that've worked with bikes? 

Also, someone mentioned a company that does decals for powdercoat??? and I think it was you who also talked about airbrushing? How detailed can you get with the airbrushing? The Specialized "S" looks awesone in the pic earlier in this thread --- is that airbrushed onto powdercoat??? waaay cool... who'd need decals with that????
Joe


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## LyNx (Oct 26, 2004)

With an airbrush you can get as detailed as you want if the person operating it knows what they're doing, but just remember, you get what you ;pay for  So if you go full custom with airbrushed graphics, fades and other fancy things the price can easily climb up to the cost of a new frame or i9 wheelset.



josephr said:


> I'm glad I found this thread! I have a Kona 4 with a scandium frame that I'd like to paint and was thinking a powdercoat would be more durable in the long run. The local PC companies I've found mostly do racecars and have only done the occasional bike, but none had even heard of Sc --- probably would've eaten a hole when they bead blasted it and, if not that, probably would've weakened the frame I'd have a cracked chainstay from the first rock garden!
> 
> Ok -- maybe I'm over-reacting....still, nice to know that just a regular ole PC isn't the way to go. I saw where you suggested two PC companies out west, but also saw where you said you know a few other PCers. I live in Birmingham, AL and currently on project in South Carolina .... can you reccomend any PCers in the area (Atlanta is good too) that've worked with bikes?
> 
> ...


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## LenMcC (Apr 10, 2007)

josephr said:


> I'm glad I found this thread! I have a Kona 4 with a scandium frame that I'd like to paint and was thinking a powdercoat would be more durable in the long run. The local PC companies I've found mostly do racecars and have only done the occasional bike, but none had even heard of Sc --- probably would've eaten a hole when they bead blasted it and, if not that, probably would've weakened the frame I'd have a cracked chainstay from the first rock garden!
> 
> Ok -- maybe I'm over-reacting....still, nice to know that just a regular ole PC isn't the way to go. I saw where you suggested two PC companies out west, but also saw where you said you know a few other PCers. I live in Birmingham, AL and currently on project in South Carolina .... can you reccomend any PCers in the area (Atlanta is good too) that've worked with bikes?
> 
> ...


yeah, scandium with regular powder isn't recommended by the easton product engineers. they say the scandium shouldn't be heated higher than 250F, while most powders cure at 350-400F. there are some low-temp powders available, but the colors are a lot more limited.

not sure of any east coast coaters besides us who are highly knowledgable about bicycles. i'm sure there are some, but i don't know of any off the top of my head.

decals for pc are made by SSS, inc. in north carolina. i haven't used them, but i know spectrum has. i prefer to airbrush whenever possible. seamless and very clean results. yes, the gold/black specialized was airbrushed with a clear powder top coat. the detail for logos is a matter of the capability of the machine used to make the masks. for our machine, 1/8" lettering is pushing it. very small or highly detailed logos are still best with water slide decals and a liquid clear coat.


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## LyNx (Oct 26, 2004)

Hey Len, got a SC Blur with Candy PC coat working on doing a bearing swap, however, the PC is in bad shape and the guy is interested in getting it redone, but I have no clue what sort of chemical stripper(s) to use or if it's even safe unless you're set up for it. Any help on stripping PC would be appreciated.


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## Ral83178 (Sep 25, 2007)

First off great thread! :thumbsup: 

I am contemplating PCing my Bianchi Sok 29er SS and was worried about the Easton Ultralite tubing. Is this the Scandium (i don't think so) that you talk about above and anything to be worried about here for baking purposes if it isn’t? Another question that I had was the “blasting”… am I better off stripping it myself and then hand it over to them (heck I may like the raw look for a while too… )? My last question is in regards to my color choice… are there different “durability” in the colors? I ask this because I am thinking of going with a black chrome PC and one shop mentioned that he didn’t know if it would be durable enough. 

Thoughts? 

Tom


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## LenMcC (Apr 10, 2007)

LyNx said:


> Hey Len, got a SC Blur with Candy PC coat working on doing a bearing swap, however, the PC is in bad shape and the guy is interested in getting it redone, but I have no clue what sort of chemical stripper(s) to use or if it's even safe unless you're set up for it. Any help on stripping PC would be appreciated.


I know these are old questions, but I'll answer them anyway, for future reference. Sorry I missed these... I subscribe to updates on this thread, but didn't see these come through.

For stripping PC, there's not much that works. You'll need to find an "aircraft" stripper that lists methyl chloride in the ingredients. It'll be a pretty slow and tedious process with a fair bit of scrubbing with a wire brush. We use an industrial stripper specifically made for PC, but it's not readily available.


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## LenMcC (Apr 10, 2007)

Ral83178 said:


> First off great thread! :thumbsup:
> 
> I am contemplating PCing my Bianchi Sok 29er SS and was worried about the Easton Ultralite tubing. Is this the Scandium (i don't think so) that you talk about above and anything to be worried about here for baking purposes if it isn't? Another question that I had was the "blasting"&#8230; am I better off stripping it myself and then hand it over to them (heck I may like the raw look for a while too&#8230; )? My last question is in regards to my color choice&#8230; are there different "durability" in the colors? I ask this because I am thinking of going with a black chrome PC and one shop mentioned that he didn't know if it would be durable enough.
> 
> ...


The only tubing I'm aware of that is a PC no-no is the Easton Scandium. The Ultralite should be fine, provided it's not a sub-brand of the Scandium. PC should never be stripped from a bicycle by blasting, unless a very specific type of plastic media is used. But that media doesn't etch the surface, so it'd have to be blasted again with conventional media to give it an anchor profile (roughen it up) and clean the metal (plastic doesn't remove oxidation, and both steel and aluminum oxidize). Best thing to do is call some coaters in the area and talk to them. It will be apparent whether they know bicycles or not, and ask them about how they'd handle it. Ask them what their process would be for stripping it. If they say "blasting", ask what kind of media they use. If they say "plastic" or "special" they're probably good. If they say anything else, they could damage it. We chemically strip frames, clean, and inspect, THEN blast carefully with high-grade media at reduced pressures.

Yes, different powder chemistries have different characteristics, and even among the same chemistry, there may be variations in durability. For a bicycle, you want a urethane or polyester powder. Good durability, good weatherability, and nice appearance. Metallics that use aluminum, like some silver metallics and black chromes, require a clear coat to prevent the aluminum from dulling and scratching. But other than that, you should be good. If a candy black chrome (tinted clear) is being applied over chrome or polished aluminum, the durability will be reduced. The mechanical bond of the powder to a very smooth surface isn't nearly as strong as PC applied to a blasted part. It should still be more durable than paint, though.


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## rallyraid (Jun 12, 2007)

How do you powdercoat an aluminum frame with scratches on them? Could I fill in 1/32" scratches running along the tubes with aluminum putty and sanding it smooth, without affecting the powdercoat outcome? 

Great thread.


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## SnowMongoose (Feb 18, 2007)

This thread is great!
Any experience with glow in the dark additives? Google netted me a few examples, (including one on a road bike that looked good) I'm just curious... I'd assume that Glow additives would work just as well via PC as via paint.

Also, thoughts on powdercoating components exposed to more abuse? I would assume that it'd hold up well. I'm thinking specifically of cranks, so lots of rubbing from shoes and occasional hits from rocks/etc
(Also,how much should one expect to pay to PC smaller parts, like a crankset?)
Thanks for sharing your expertise!


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## LenMcC (Apr 10, 2007)

rallyraid said:


> How do you powdercoat an aluminum frame with scratches on them? Could I fill in 1/32" scratches running along the tubes with aluminum putty and sanding it smooth, without affecting the powdercoat outcome?
> 
> Great thread.


If the scratches are pretty superficial and are on a beefy part of the frame, you may be able to block them down with some 220 grit paper. Using a block (can be a sanding block or even just a block of wood) keeps the surface nice and flat so you don't get waves. If the scratches are superficial, but sanding the metal isn't an option, you'd want to lightly block the metal to debur it, then use a powder primer like KL primer. KL is self-leveling to a certain extent, and it sands relatively easily. Block down the problem areas and feather out the edges if necessary, then apply the color coat. Depending on the color, it may be necessary to apply a second color coat to achieve uniform color.

For heavier gouges, I've heard of some coaters having success powder coating over products like JB Weld, but in my experience, they don't deliver flawless results. Tiger Drylac, a powder manufacturer, has two-part epoxy product called EpoStrong, made specifically as a powder filler, and its pretty decent. Once the EpoStrong is oven-cured, it can be blocked down and either primed and blocked, or if the repaired surface is sufficiently smooth, the color coat may be applied directly over it. Again, since there will be color variation between the metal and the filler, it may take two coats to get a uniform finish.


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## LenMcC (Apr 10, 2007)

SnowMongoose said:


> This thread is great!
> Any experience with glow in the dark additives? Google netted me a few examples, (including one on a road bike that looked good) I'm just curious... I'd assume that Glow additives would work just as well via PC as via paint.
> 
> Also, thoughts on powdercoating components exposed to more abuse? I would assume that it'd hold up well. I'm thinking specifically of cranks, so lots of rubbing from shoes and occasional hits from rocks/etc
> ...


Thanks!

I've never shot glow-in-the-dark additives, because from what I've read about them, they completely suck. They're not UV-stable. The first time it's exposed to sunlight, it almost completely kills the phosphoresence. Kinda defeats the purpose. Maybe a manufacturer has figured out a UV-resistant version. I can look into it for ya.

Yeah, powder is good for heavily-abused parts. It's not indestructable, but it's adhesion is vastly superior to paint. It'll still scuff, and things like cranks that get rubbed with mud every pedal stroke, it'll eventually burn through like any other finish including ano. We generally charge around $40-50 for a set of cranks, depending on how much damage needs to be cleaned up, whether the bash guard or rings are getting done, too, etc. Little stuff like levers can be done for like $5ea.


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## qkenuf4u (Jan 24, 2009)

good reading and im learning as i read... thanks for the info about the frame material and what i cant/can blast/cook.... that will be a life saver if the owner stays in business long enough..  
im the MAIN PC guy at a local PC shop (POWDER COAT PLUS) here in lake havasu city arizona... glad to see im not alone on that red bleeding thru white problem... :madman: :madmax: 
my first week at the shop and i found out the hard way about that problem (FYI HAVE NEVER WORKED WITH PC TILL THAT TIME ) my boss runs off to mexico and leaves me on my own. i did get like 5 jobs out the door that day but those red jerry cans with TAN over them made it an awful long day... :eekster: 
now if only someone would give out their secret to keeping the red from bleeding.... in my case it would have been taking all the red paint OFF FIRST or putting a PC PRIMER over it first. :nono: but then with 1 week under my belt how was i supposed to know that....:skep:



LenMcC said:


> For heavier gouges, I've heard of some coaters having success powder coating over products like JB Weld, but in my experience, they don't deliver flawless results. Tiger Drylac, a powder manufacturer, has two-part epoxy product called EpoStrong, made specifically as a powder filler, and its pretty decent. Once the EpoStrong is oven-cured, it can be blocked down and either primed and blocked, or if the repaired surface is sufficiently smooth, the color coat may be applied directly over it. Again, since there will be color variation between the metal and the filler, it may take two coats to get a uniform finish.


you could use LAB-METAL also for deep scratches/gouges...

talking about under/over curing... what ive come to find out is leaving it in the oven over night ALWAYS helps it flow out and be VERY VERY SMOOTH. i always cook the last 3-4hrs of the day. if things dont have to go out the door i just turn the oven off and leave them in overnight... aways a very nice smooth finish in the morning. i did a go cart frame couple weeks back that looked orange peeled at the end of the day. guy wasnt happy so i put it back in the oven and left it over night.. it looked 10x better/smoother by morning but not perfect. he wanted smooth/shiney cause he was gonna do the sheet metal in paint (over the black PC we put down ??)

as for powder over powder... if its powder and cold we put it in the oven and let it cook till about 260-300* and pull it out.. the heat creates the static charge you need for the powder to stick and if its not TO HOT it will stick better than a bare metal grounded piece... then back in the oven for final cure... i lay it on till it stays a powder (the heat will cook the first layer instantly) only powder ive had problems with so far of putting to much on has been CLEAR (cardinal i think it was)

we use NIC, CARDINAL, DRYLAC, few others.... heres my bike i just finished up in APPLE GRANNY GREEN...


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## Operandi (Aug 11, 2010)

Awesome thread, *LenMcC*, thanks for keeping it going.

I have a 00 S-Works M4 Stumpjumper that want to repaint, (and rebuild) take it from yellow to flat black and make it look like a later model S-Works, with some custom decals over the paint / powder coat.

I don't know much about the alloy but I know the M4 alloy dose have Mg in it but I assume that is a very small makeup of the metal I'm thinking I don't have worry about strippers reacting with it or the PC weakening the frame. Am I correct in this?


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## DFA (Jan 26, 2004)

I've picked up a P2 that was previously powder coated. I want to strip it and paint it to color match with a frame. What are good name brand strippers I can pick up at my local hardware stores, and what should I stay away from? How long should I leave the stripper on for?

TIA


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## LenMcC (Apr 10, 2007)

Operandi said:


> Awesome thread, *LenMcC*, thanks for keeping it going.
> 
> I have a 00 S-Works M4 Stumpjumper that want to repaint, (and rebuild) take it from yellow to flat black and make it look like a later model S-Works, with some custom decals over the paint / powder coat.
> 
> I don't know much about the alloy but I know the M4 alloy dose have Mg in it but I assume that is a very small makeup of the metal I'm thinking I don't have worry about strippers reacting with it or the PC weakening the frame. Am I correct in this?


these answers are long overdue, and i apologize. i'm going to check my thread subsciption...

chemical stripper should be fine. many strippers attack aluminum, too, just slower. frames should always be closely monitored, and checked every 10min at max. usually only takes 10-15min in the tank. then into a neutralizing rinse tank, then a detergent scrub and dry cycle in the oven.


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## LenMcC (Apr 10, 2007)

*DIY powder stripping*



DFA said:


> I've picked up a P2 that was previously powder coated. I want to strip it and paint it to color match with a frame. What are good name brand strippers I can pick up at my local hardware stores, and what should I stay away from? How long should I leave the stripper on for?
> 
> TIA


I won't lie, stripping powder yourself sucks. You need a stripper containing methyl chloride. a good place to look is with "aircraft" strippers, but read the ingredients.

Anything that will touch powder is gonna be a little dangerous, so serious gloves, goggles, long sleeves and pants, and good ventilation are all gonna be crucial.

Lay out some heavy plastic disposable tarp. Spray down the frame. Watch it. It probably won't do anything. Check back in 20min or so and give it a scrape with a putty knife to see if it's working. If it is, you're on the right track. It's going to take reapplication every 10-20min (you want to keep it wet) and you're going to go through 2-3 cans of stripper. Once it softens up enough, you can start scraping it off, and usings a wire brush at the unions. Patience is key, let the stripper work rather than kill yourself with the scraping/brushing. After you get it all off, she's gonna need a thorough wash down.


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## Golem builder (Jul 31, 2009)

Hi,

How bad is the smell of melting powder? I just ask before driving my neighbour crazy with my (maybe future) home operation.

Thanks!


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## LenMcC (Apr 10, 2007)

It's not generally bad. They all smell different, and I can usually tell what color is in the oven just by smell. Some of the textured colors smell funky, but not overwhelming. Flat blacks tend to be smokey, but the smell isn't bad. I'm sure it'd be far less offensive to your neighbors than liquid paint fumes. You should be fine, particularly if you're sticking to small stuff.


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## D.F.L. (Jan 3, 2004)

Len,

I have a frame that needs to be 3-tone and I'm starting with a solid powder base(Prismatic brand). The plan is to add the 2nd and 3rd hues via wet paint. My question is if you have experience with this and if either enamel or urethane will react badly with the powder base. I don't want any surprises.

Thanks!


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## LenMcC (Apr 10, 2007)

D.F.L. said:


> Len,
> 
> I have a frame that needs to be 3-tone and I'm starting with a solid powder base(Prismatic brand). The plan is to add the 2nd and 3rd hues via wet paint. My question is if you have experience with this and if either enamel or urethane will react badly with the powder base. I don't want any surprises.
> 
> Thanks!


What Prismatic color did you have in mind? I primarily use Prismatics, so if I've shot it, I can give you some pointers on the specific color.

I'll address your last point first... The custom powder coating world is full of surprises! Powders all shoot differently, lay differently, flow differently, and react differently with top coats of powder or paint. And to make things more difficult, there are no such thing as 30-year custom powder veterans like there are with wet paint. Powder technology is also progressing at a rapid rate, which is usually great, but sometimes introduces new problems, like sublimation (base coat bleeding into top coat).  Take some extra time up front and shoot a sample exactly as you would the final product. It can save you a lot of time if there ends up being a funny reaction (usually more of a concern with powder-over-powder) or an adhesion problem.

That being said, here is my advice for this project:
1) Stick to polyesters or urethanes for the powder. Those are the two kinds that belong on a bicycle. They've got the best combination of durability, corrosion-resistance, UV-stability, and aesthetics for bikes.
2) I have used enamels (1-Shot) and urethanes (DuPont, Kustom Shop) with success over powder. BUT...
3) Nothing likes to stick to powder... So it is very important to thoroughly scuff the powder surface before applying the paint.
4) To scuff, use grey (very fine) Scotchbright. Its a lot easier and more consistent than a fine grade sandpaper. Get every square inch and every cranny.
5) If you're base coat is metallic (part of the reason I asked what powder color you want to use), you CANNOT scuff it, or you'll destroy the metallic effect. To overcome this, you'll need to shoot the metallic, partially cure the metallic, let the frame cool, apply a clear powder top coat, then fully cure them together. Now you can scuff the clear and keep the metallic intact.

I think that's about it. If you run into any hiccups or have more questions along the way, feel free to contact me. Email or phone will be faster if you're elbow-deep and need an immediate pointer. Contact info is on figurefinishing.com. Good luck and have fun!


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## D.F.L. (Jan 3, 2004)

Len, thanks so much. The color is a solid, 'white out', and I'm happy to hear that either paint type won't react badly. And I already have plenty of grey scuffs!

Thanks again for this thread and all the great info!


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## Deerhill (Dec 21, 2009)

@ what temperature does the heat start to affect the temper or structure or strength of the different aluminum alloys? say 6000 aluminum up to 7000 aluminum?


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## willtsmith_nwi (Jan 1, 1970)

LenMcC said:


> Hey guys,
> 
> Welcome to the way-more-than-you-ever-wanted-to-know-about-bicycle-finishing thread!
> 
> ...


Looks awesome. I have a warning to all though. If you remove the factory paint you void any warranty you had.


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## Deerhill (Dec 21, 2009)

willtsmith_nwi said:


> Looks awesome. I have a warning to all though. If you remove the factory paint you void any warranty you had.


good point, for the few companies that can actually offer the lifetime warranty


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## Beaker13 (Feb 10, 2009)

****** Bag


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## Operandi (Aug 11, 2010)

Alright so not too long ago I went through the strip and powdercoat process. Bellow is the various steps I went though on my 00 M4 S-Works hardtail.

First for reference here is what it looked like near the end of the 2010 riding season. It was kinda beat up needed a fair amount of replacement hardware. I never really cared for the yellow anyway.....









Here is the frame about 75% stripped. Getting to this point was fairly quick maybe 1-2 hours, but getting the last 10% out of the hard to reach and hard to scrap spots was the other half of the battle.









This the frame down to the bar AL, or at least 95% there. Pretty sweet looking and I actually contemplated going raw AL but I wasn't sure I'd like it the long haul.








https://i.imgur.com/R6G5fso.jpg

Here is the frame back from the powder coater, black.









These are decals back from the local printer. I had a friend draw them up manually working from pictures I had taken from the original bike as well as working off of some late model S-Works to get the look I was going for. She did a great job.









The frame with decals applied along with 2 or 3 (can't remember exactly) coats of clear coat.

























And of course the finished bike. New Magura Menja fork, XTR cranks 90mm Thompson stem, Truvativ World Cup carbon flat bar, Chris King/DT Swiss XR425 wheels, Fizik Tundra saddle (not in the pics XTR 972 rear derailleur and red Woodman SL post clamp). Stuff I kept include the XTR V-brakes and the XT shifters, though I'll probably replace the shifters at some point with a some newer XTs as these don't feel so crisp anymore, also have a 80mm Magura Durin coming as the last upgrade which should drop the weight to right around or under 21lb fully loaded.

































Overall I'm quite happy with how this turned out.


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## SAVAGESAM (Jan 14, 2008)

I have a question Len. I have a plain vanilla D.B. Response sport that I've wanted to get painted or P.C.ed. I want to paint it in a reflective white (think the same paint they use on street signs) I read that the thing that makes it reflective is ground up glass. Can this be P.C. or would it have to be conventional? Thanks for this thread.


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## Dave-Uk (Sep 14, 2014)

*Vintage Skyway decals.*

Hi guys. Just joined. Thanks for having me.

I have a question! Its about an old Barn find Skyway BMX i imported.
The Decals are part of the finish, perhaps under a clear coat. It looks very authentic to me but skeptics are saying it was redone. no one has ever seen one similar, they all have stickers instead. The finish looked easily twenty+ years old and i have had it for 6 years. The decals have a TM on them.
I ve been told that powder coating over powder is impossible. Ive been told that high temp graphics dont even exist either. I cant find any of these Skyway decals anywhere, all stickers
Is it likely that they are fake decals?
How much work would it be for someone to have reverse engineered the original decals in the 80`s then apply and clear coat them? Why would anyone do that when you can just put stickers on.
Here`s a couple of pics















Thanks in advance for any help.


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