# Dunk Tank - corrodes inside tubes?



## TheWoodsman (Aug 27, 2010)

On the face of it, filling every tube full of water before paint and framesaver doesn't seem such a great idea. Once rust starts it only goes one way....prevention is better than cure - I'll stop there 

What is the consensus on this...

(Apologies if it has been discussed before, my search didn't reveal much)

Cheers


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## Walt (Jan 23, 2004)

*I will just say this...*

Leaving flux inside the frame is much worse than getting it a little wet.

-W



TheWoodsman said:


> On the face of it, filling every tube full of water before paint and framesaver doesn't seem such a great idea. Once rust starts it only goes one way....prevention is better than cure - I'll stop there
> 
> What is the consensus on this...
> 
> ...


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## TheWoodsman (Aug 27, 2010)

Walt, I like your description of the dunk tank - ''a little wet''.


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## Walt (Jan 23, 2004)

*Ok.*

If dunking frames was a problem, there would be tons of nice hand-made frames disentigrating into rust, because tons of builders use them. So the "consensus" is that your concern is misplaced. If you even sort of take care of your steel frame, rust will never be a problem, dunk tank or no.

-Walt



TheWoodsman said:


> Walt, I like your description of the dunk tank - ''a little wet''.


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## jgerhardt (Aug 31, 2009)

It really isn't that big of a deal to dry the inside of the tubes with a little air from a compressor. And, like Walt says, the advantages of getting rid of all of the flux far outweigh any disadvantage of a little dunking.


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## willapajames (Dec 18, 2005)

Walt said:


> If dunking frames was a problem, there would be tons of nice hand-made frames disentigrating into rust, because tons of builders use them. So the "consensus" is that your concern is misplaced. If you even sort of take care of your steel frame, rust will never be a problem, dunk tank or no.
> 
> -Walt


My nice hand-made frame (Willits Trail King, steel) disintegrated into rust, and I took excellent care of it. Don't know about the previous owner though... 








I still wonder WTF happened to it...


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## febikes (Jan 28, 2011)

willapajames said:


> My nice hand-made frame (Willits Trail King, steel) disintegrated into rust, and I took excellent care of it. Don't know about the previous owner though...
> http://a4.sphotos.ak.fbcdn.net/hphotos-ak-snc6
> I still wonder WTF happened to it...[/QUOTE]
> 
> ...


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## Walt (Jan 23, 2004)

*Just FYI*

That is a major bummer, but since Wes was always (afaik) a TIG guy, that bike probably was never dunked. I use a pot of boiling water to remove exterior flux (brazeons) from my frames, but don't dunk, because it's not really necessary. I *think* most TIG people do the same.

FWIW, to me, that does not look like rust damage. But I have never really seen anything like it either...

-Walt



willapajames said:


> My nice hand-made frame (Willits Trail King, steel) disintegrated into rust, and I took excellent care of it. Don't know about the previous owner though...
> 
> I still wonder WTF happened to it...


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## TheWoodsman (Aug 27, 2010)

Interesting, I totally get the fact that you can dry the tubes with heat/air. Would that not leave flash rust (that you can't access) once dried (Walt - put the pitch fork down  I'm just trying with an open mind to see why this process is becoming so popular - obviously it is easier and more cost effective than setting up with shot blasting, which is what nearly all the builders here in the UK have been using to de-flux up to now.

I'm not fully convinced, but I can see your argument, which was the purpose of the thread. So, I thank you for your candid responses.


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## smdubovsky (Apr 27, 2007)

I'd like to see how they shot blast the inside of the tubes...


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## CurbDestroyer (Mar 6, 2008)

smdubovsky said:


> I'd like to see how they shot blast the inside of the tubes...


You just beat me to asking that same question by 2 minutes. I fillet braze and flux inside the tube about an inch. I let mine dry out for a day, then blast the inside of the tubes with frame saver. I've never had a frame power coated and if I remember right when they bake it on isn't inside a 400 degree oven. In this case should you paint the frame first?


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## Mr.Magura (Aug 11, 2010)

I made a couple of experiments a while back, regarding this issue.

Washing out the flux is mandatory. The only way I have found to be bullet proof, is boiling the frame in water. 
If left inside the tubes, it will eat the tubes real quick, no matter what you do.

I tried a few different solutions to rust protect the frames inside, and it turned out that something as useless as WD40 is a good solution, just as good as Framesaver. Tri-Flow does the trick as well.

Around here they have a nasty habit of spraying salt on the roads in the winter, so I made the test with the tubes submerged in a 0.5% salt solution, to simulate a worst case scenario. 
I did the test over half a year, which ought to reveal any nasty surprises. 

Magura


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## TheWoodsman (Aug 27, 2010)

I'm obviously not making my point well enough, as I had up to now thought the objective of flux removal was to enable the builder to work on the joints and prepare for painting the frame - without flux on it of course. You're completely missing my point Smd... and curbdestroyer - of course I'm not suggesting blasting inside the tubes, that is my point - unable to access where the water has been. 

Thankfully, Mr.Magura is getting things back on track to a useful open minded discussion to this process. I'm now starting to see that the primary objective of the dunk tank is to remove the corrosive flux from within the tubes, and the water is the lesser of the evil in this process. Correct?

Phew!

Be happy everyone


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## Walt (Jan 23, 2004)

*Yes.*

That is what we have been saying, yes.

-W



TheWoodsman said:


> I'm now starting to see that the primary objective of the dunk tank is to remove the corrosive flux from within the tubes, and the water is the lesser of the evil in this process. Correct?


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## unterhausen (Sep 28, 2008)

there is nothing wrong with light surface rust. I'm assuming most steel bikes have not been treated with framesaver and have a layer of light surface rust on the interior of the tubes. The problem is if the conditions that promote rust have continued to exist. 

From what I've seen, residual flux doesn't really promote corrosion. Which is good because there are a lot of builders that have just left it in the tubes.


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## Woodsy (Aug 15, 2005)

Mr.Magura said:


> I made a couple of experiments a while back, regarding this issue.
> 
> Washing out the flux is mandatory. The only way I have found to be bullet proof, is boiling the frame in water.
> If left inside the tubes, it will eat the tubes real quick, no matter what you do.
> ...


Wow, thanks for this experiment! :yesnod: Can you describe in greater detail?!


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## wycx (Sep 2, 2005)

Anyone measured the pH of their dunk tank water after soaking a frame?

If you really wanted to be sure, you could soak in hot water to dissolve the flux, then soak in dilute NaHCO3 (sodium bicarbonate) solution to neutralise any remnants of flux, and then a rinse/soak in clean water. It is three times the number of steps and you might experience diminishing returns, but you could sleep easy.


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## dbohemian (Mar 25, 2007)

unterhausen;8521984
From what I've seen said:


> This is my observation as well. I have left flux on the outside of tubes for an extended period with no corrosion at all (i.e old projects in shed) In fact the non fluxed parts rust and the fluxed ones do not.
> 
> Some pretty famous builders do not remove residual flux with dunk tanks. I have repaired a number of frames, seen flux near the joints and never seen a serious corrosion issue there. The man tells us that its corrosive or that has become apocrypha but I am just sayin' show me an example of a frame ruined from flux corrosion? My guess is that acid based fluxes on copper pipping cause corrosion if not removed and people translated this to bike frames.


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## teatreetim (Nov 14, 2011)

Silver brazing flux corrodes like crazy. I clean this up pedantically. Bronze brazing flux doesnt worry me too much.


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## dbohemian (Mar 25, 2007)

teatreetim said:


> Silver brazing flux corrodes like crazy. I clean this up pedantically. Bronze brazing flux doesnt worry me too much.


Really? Since the primary ingredient of silver fluxes is similar (potassium flouroborate and tetraborate) this seems unlikely to me and not what I have witnessed. These compounds are fairly inert in and of themselves. When exposed to moisture they can break down into acids (hydroflouric) but I wonder what the concentration really is? Pretty low is my guess and hydroflouric acid is a chemical in many rust removers so we may see corrosion but not in the form of rust.

Today I will coat one end of a tube in silver flux, the other in bronze flux and let it sit. I will report back in 6-12 months with what I find. Seems like we can test this one fairly easily.

Certainly my weather will be different than yours and my flux will be different as well but it should give us a reasonable answer.


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## JaquesN (Sep 14, 2009)

dbohemian said:


> Today I will coat one end of a tube in silver flux, the other in bronze flux and let it sit. I will report back in 6-12 months with what I find. Seems like we can test this one fairly easily.


Thanks for undertaking this experiment! To do it properly, though, shouldn't you heat the flux to brazing temperature as well? I don't know if there's any chemical change in the flux, but it does seem to stick more when it's been heated.


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## A. Spence (Sep 25, 2009)

dbohemian said:


> Really? Since the primary ingredient of silver fluxes is similar (potassium flouroborate and tetraborate) this seems unlikely to me and not what I have witnessed. These compounds are fairly inert in and of themselves. When exposed to moisture they can break down into acids (hydroflouric) but I wonder what the concentration really is? Pretty low is my guess and hydroflouric acid is a chemical in many rust removers so we may see corrosion but not in the form of rust.
> 
> Dave,
> 
> ...


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## unterhausen (Sep 28, 2008)

I had a fork that I didn't like the way it brazed up (silver). So from about 1980 until recently I left it sitting around with silver flux on it. It was just like Dave said, under the flux there was no corrosion, everywhere else was rusted. Not sure how much different most silver fluxes are from back then, it impresses me that Safetysilv hasn't changed a bit.

The whole magic of flux is that it becomes active at temp, so it doesn't surprise me much that it's not very active at room temperatures


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## shandcycles (Jan 15, 2008)

Before I had a dunk tank big enough for a whole frame, I used to wrap wet rags/towels round my joints to soak off the flux. I had an issue one time where I left a wrapped a silver brazed frame kicking around for about 3 or 4 days. When I unwrapped it, there were small 'channels' etched into the frame where individual flux soaked threads had been wrapped round. These were deep enough to feel with a fingernail and only took 3 or 4 days to appear. If I'd left it longer, I'm not sure how bad it would have got but it was bad enough to have to junk the frame and start over. 

This was with Sif Silver Flux, a powder I mix to form a paste. I don't do that anymore but I think I kept the frame (or at least the tubes), I'll see if I can find it and take some pics.

Steven


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## unterhausen (Sep 28, 2008)

I have seen people recommend the wet rag treatment. I tried it, and it turns out not to be a real good idea. I didn't get the impression the corrosion was really due to the flux though


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## Mr.Magura (Aug 11, 2010)

Woodsy said:


> Wow, thanks for this experiment! :yesnod: Can you describe in greater detail?!


The test was made with silver brazing and flux.

Now seeing the later comments, it seems clear to me, that some types of flux is an issue, and some are harmless.

The test I made, was based on an old type of flux, if interested I can see if I can find out which it was exactly.

The type of flux I use, will even make things corrode if just left outdoors.

Maybe it's time we make a list of flux that have the properties we need, and does not promote corrosion?

Magura


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## teatreetim (Nov 14, 2011)

I use silver to braze stainless steel to CroMo so need it needs to be corrosive. I use 45% silver and Comweld flux no 2.


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## NSCustoms (Dec 7, 2011)

Is it possible to add a metal preservative to your dunk tank water? Maybe some of the water soluable coolant used for cnc machines. I know that stuff does not cause rust and it is diluted at pretty low concentrations?


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## NSCustoms (Dec 7, 2011)

*A possible solution for dip tank corrosion*

This is what I was thinking, im going to order some and test it out. Ill post up results.
McMaster-Carr
misting ang cooling


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## Mr.Magura (Aug 11, 2010)

But what do you expect to gain by mixing coolant in the tank?


Magura


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## NSCustoms (Dec 7, 2011)

Mr.Magura said:


> But what do you expect to gain by mixing coolant in the tank?
> 
> Magura


Rust inhibition. It is not oil based and has rust inhibitors. So it should prevent any corrosion from forming from the water being in the tubes.


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## Mr.Magura (Aug 11, 2010)

NSCustoms said:


> Rust inhibition. It is not oil based and has rust inhibitors. So it should prevent any corrosion from forming from the water being in the tubes.


That's not the way it works.

It is partly in the coolant as lubrication for the cutting tools, and partly to avoid light rust after the machining operation due to the water.

After that, it makes no difference, and washes right off if exposed to water.

EDIT: and it will mix with the salt from the flux, thus being corrosive in the end.

Magura


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## NSCustoms (Dec 7, 2011)

So, if I boil the frame in a water / coolant solution to remove flux, then heat the frame in my bake box prior to evaporate out the solution. Then prep the outer tubes for paint, wouldn't that achieve the goal of not having rust form from the dip tank process? I would then tret the inside of the tubes with an oil based preservative. Or am I missing something?


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## CurbDestroyer (Mar 6, 2008)

Probably does taste as good as Canadian Maple syrup, but spray in the tubes once a year and I'd say your good to go.

Forms a transparent, soft, waxy film for protection and lubrication 
Inhibits rust and corrosion; protects steel parts indoors for up to 2 years 
Inhibits exfoliation and filiform corrosion of aluminum 
Penetrates to displace moisture 
Does not contain chlorinated solvents or silicone 
Nonconductive 
Safe on most surfaces 
Meets NSF requirements for H2 Registration: #129027 (aerosol), #059849 (bulk) 
Accepted by the Canadian Food Inspection Agency - Category n1


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## shandcycles (Jan 15, 2008)

This is a non issue! There's no problem, so why are you looking for a solution??? If you're worried about rust forming, just dry the frame ffs.


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## NSCustoms (Dec 7, 2011)

*Im overthinking*

Here is a quote from a shop notebook from 1881
"Johnnie was one of the most inventive little cubs that ever grew up in a machine shop. He would much rather spend a day in inventing ways to do something that nobody wanted done than to devote an hour or so to doing something useful. This does not mean that Johnnie was lazy or sought to shirk his share of whatever was doing. He was a bright, active lad, with an aptitude for mechanics... "

Sometimes I relate to much to Johnnie......


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## Mr.Magura (Aug 11, 2010)

NSCustoms said:


> Here is a quote from a shop notebook from 1881
> "Johnnie was one of the most inventive little cubs that ever grew up in a machine shop. He would much rather spend a day in inventing ways to do something that nobody wanted done than to devote an hour or so to doing something useful. This does not mean that Johnnie was lazy or sought to shirk his share of whatever was doing. He was a bright, active lad, with an aptitude for mechanics... "
> 
> Sometimes I relate to much to Johnnie......


:thumbsup:

Magura


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## Patagrande (Jul 26, 2010)

The company that makes POR 15 offers a "Tank Sealer" kit, although the product is geared towards sealing gas tanks, as both a preventative measure and restorative option, I tried it on a steel fork.

I live in the rain forest, and all my frames are Al, but some forks are not.

The system, is a 3 step process.

1- Thorough cleaning via an industrial degreaser, which comes in the form of a concentrate to be diluted and used in hot water. (hang tight Woodsman...), followed by a rinse, preferable in hot water to aid drying.

2- A liquid "galvanizing" solution that is also water soluble and is best used in hot water, is used to "clean" existing rust, and then deposit a phosphate coating, which is meant to inhibit new rust and also as a "primer" of sorts. You are supposed to rinse this as well and let part dry prior to sealing.
In reality, I was told I could leave the coating alone, if I was not ready to seal or paint.

3- The last step entails sloshing a low viscosity epoxy around, I injected it using a very large(cattle) syringe from the lower vent holes, on each fork leg, then let it drain. I used a ball dabber to do the inside of the steerer tube. After a few days, I sprayed the outside of the steerer tube with a goop called 6to1 which I have been using to coat one of my sailboats outboard.

Warning! if you opt to try this, have a plan, or it could get messy!


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