# DIY powdercoating noob questions



## JaquesN (Sep 14, 2009)

Hi All,

We are just getting started with powdercoating. Now that I've tried it out on some small parts, I have some questions for anyone out there who's powdercoating frames. I'm using an Eastwood dual-voltage gun and, until we build the full-sized oven, a toaster oven at 400 degrees F to gloss, then 450 for ~20 minutes.

Do you pre-heat the frame? If so, for how long / what temperature?

Do you have any special techniques for moving the piece? I was thinking I'd make some handles that fit the bb and seat tube.

How do you avoid the "orange peel" effect? Everything I've coated so far has that ripple in the surface. 

Thanks for any advice or tips.

-JN


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## shiggy (Dec 19, 1998)

JaquesN said:


> Hi All,
> 
> We are just getting started with powdercoating. Now that I've tried it out on some small parts, I have some questions for anyone out there who's powdercoating frames. I'm using an Eastwood dual-voltage gun and, until we build the full-sized oven, a toaster oven at 400 degrees F to gloss, then 450 for ~20 minutes.
> 
> ...


Do not pre heat the object being coated.
450F is too hot and may be the reason for the orange peel. Most powder cures at ~200C for 15-20min (depending on color) in a preheated oven.

Bolts in the bottle brazeons (which you need anyway) make good handles, plus a finger inside the HT, ST or BB shell. The oven rack for the frame is more important.


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## mattty (Feb 26, 2009)

Hi

I built a large oven and have done many frames now. My setup has a cart and track. I use seatposts to suspend the frames while spraying/baking (most of my frames have integrated seatclamps) :

http://stoutbikes.blogspot.com/2011/02/aside-from-little-bit-of-electrocution.html

No preheating of parts for spraying, but prebaking is a necessary step in the cleaning process to remove oils. I usually prebake for ~10 minutes at ~400 degrees, then a final Xylene wipedown.

My experience is that some orange peel is unavoidable, and is usually the result of shooting the powder in one spot for too long. Using a circular or agitated/sweeping motion helps get a uniform surface. Another tip is to have the setup on a switch so you can easily shutoff power and wipe the electrode every few minutes. This improves the charge of the powder coming out of the gun.

The most useful tool that I use is a bright bike light to see the thin spots (that are otherwise invisible). I have messed up too many powdercoat jobs by not looking over every inch of the frame, with the light, to see any thin (visible substrate) spots.


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## JaquesN (Sep 14, 2009)

Hi. Thanks for your reply.



shiggy said:


> Do not pre heat the object being coated.
> 450F is too hot and may be the reason for the orange peel. Most powder cures at ~200C for 15-20min (depending on color) in a preheated oven.


200° C = 392° F. Are you saying that the difference is important?



shiggy said:


> Bolts in the bottle brazeons (which you need anyway) make good handles, plus a finger inside the HT, ST or BB shell. The oven rack for the frame is more important.


Yeah, I'll be practicing getting the piece into the oven without knocking any powder off, and will design some sort of fixture to hold it while in the oven, so no powder touches anything else. I was thinking of a little stand bolted to the BB.


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## JaquesN (Sep 14, 2009)

mattty said:


> Hi
> 
> I built a large oven and have done many frames now. My setup has a cart and track. I use seatposts to suspend the frames while spraying/baking (most of my frames have integrated seatclamps) :
> 
> http://stoutbikes.blogspot.com/2011/02/aside-from-little-bit-of-electrocution.html


That is a real nice setup. How many heating elements do you have in that oven? Are they all on the bottom?

Also, what did you use for insulation?



mattty said:


> No preheating of parts for spraying, but prebaking is a necessary step in the cleaning process to remove oils. I usually prebake for ~10 minutes at ~400 degrees, then a final Xylene wipedown.


Interesting. How does the pre-heat help clean off the oils? One piece I tested had just been sanded. I would think that would remove most of everything, though come to think of it, it might have left some residue from the sandpaper.

So you are shooting powder when the piece has cooled back down to room temperature?



mattty said:


> My experience is that some orange peel is unavoidable, and is usually the result of shooting the powder in one spot for too long. Using a circular or agitated/sweeping motion helps get a uniform surface. Another tip is to have the setup on a switch so you can easily shutoff power and wipe the electrode every few minutes. This improves the charge of the powder coming out of the gun.


OK, thanks for all the tips. I did not know it was even possible to shoot too much powder on a given spot. I thought that the powder would only cling at a certain thickness.

Thanks,
Jim


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## shiggy (Dec 19, 1998)

JaquesN said:


> Hi. Thanks for your reply.
> 
> 200° C = 392° F. Are you saying that the difference is important?
> 
> Yeah, I'll be practicing getting the piece into the oven without knocking any powder off, and will design some sort of fixture to hold it while in the oven, so no powder touches anything else. I was thinking of a little stand bolted to the BB.


Yes, the temp is important. Go check the tech docs for your powder.

No need to bolt the frame to a rack. Use anything that is stable and can support the frame by inserting into the HT or ST works.


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## JaquesN (Sep 14, 2009)

The docs say to preheat the oven to 400° F, put the part in there until it glosses over, then bake at 450 for 20 minutes. I will experiment with a lower temperature.

This is Eastwood black gloss powder.

I'll also try cleaning the parts better.

Thanks again!


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## shiggy (Dec 19, 1998)

JaquesN said:


> The docs say to preheat the oven to 400° F, put the part in there until it glosses over, then bake at 450 for 20 minutes. I will experiment with a lower temperature.
> 
> This is Eastwood black gloss powder.
> 
> ...


I worked two years doing production coating. Was always 200C for 20min (max). Smooth and glossy was the norm.

Oil/grease/dirt spots will give fisheyes rather than orange peel.


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## mattty (Feb 26, 2009)

My oven has four oven heating elements, all on the bottom.

The insulation panels are ~1.5' by 4' fiberglass insulation boards

Yeah, the oil spots cause tiny bubbles. They usually occur when one skips pre-baking. This process brings any residual oil, left in the porous parts, to the surface. This is especially necessary if one powdercoats over straight gauge tubes (that still have factory coating on them)... Or when sanding/blasting is not desired.

My process is: clean with Xylene, prebake, let cool, Xylene again, apply powder, flashlight inspection time, prescribed curing schedule


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## chernichovsky (Mar 11, 2011)

*powder*



JaquesN said:


> Hi All,
> 
> We are just getting started with powdercoating. Now that I've tried it out on some small parts, I have some questions for anyone out there who's powdercoating frames. I'm using an Eastwood dual-voltage gun and, until we build the full-sized oven, a toaster oven at 400 degrees F to gloss, then 450 for ~20 minutes.
> 
> ...


We preheat always - helps powder clinging on the metal when applying it.
Start with tubes then BB and H tube (cause they hold heat longer)
Preheating has always anf effect on finish from our experience.

Oven - We build one eventualy. Note that with analog heat termostat you about a 15C degrees of error. Look up Digital heat thermometer on the web and get one of those.
We got them wired up to some 4900 watts of heating units, turbo fans and more temperture sensores to get an even temperture throughout the oven.

Quite a task getting an oven staibelized - but results get better with heat control
(just like fillet brazing )

Note how the frames is held through out the whole process - very important as well
Getting the frame in there with no vibrations also affects finish quality and defects.

Good luck! Its the best frame finish - most durable and suitable for bikes.

more pics here : Chernichovsky-Bicycle-Labs
http://www.facebook.com/pages/Chernichovsky-Bicycle-Labs/115524605173623


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## geckocycles (Sep 3, 2006)

I have also seen pizza ovens used. Frame is on it's side.


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## JaquesN (Sep 14, 2009)

Chernichovsky, looks like you are achieving some very beautiful results.

Thanks again for all of the info.

I'm going to invest in a digital thermometer and do some more test pieces. It does seem like this whole process is like brazing. 

For those who have made their own ovens, would you say that a window is required?


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## mattty (Feb 26, 2009)

A window certainly helps with determining when to turn the heat down from flow temp to curing temperature. I used some inexpensive cooking dishes from a superstore and sealed them in with some heat resistant adhesive rubber from an autoparts store.

I dont preheat parts for adhesion, mostly due to my past experiences outsourcing my frames to businesses that _did_ preheat. The result was a very thick, heavy coat that was prone to drips. I have also learned that just because one says that they have "years of experience in the business" means absolutely **** regarding bicycle frames.


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## mattty (Feb 26, 2009)

JaquesN said:


> The docs say to preheat the oven to 400° F, put the part in there until it glosses over, then bake at 450 for 20 minutes. I will experiment with a lower temperature.
> 
> This is Eastwood black gloss powder.
> 
> ...


You might re-read the instructions, I seem to remember my Eastwood powders glossing at 450f and curing at 400f for 20 minutes.

My Powderbuythepound.com powders all have different schedules as well.


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