Weldable coats

[Amaro Bikes]

Hi all.

This post/question is about the already discussed matter of frame inside rust protection. Many of us use framsaver or similar solutions, but this means it needs some kind of future re-application and this is usually up to the customer, so can't really be warrantied, therefore (look at that english delicacy!), some other solutions are commented/used by other builders, but I have some deep concerns about them:
-Galvanization or some other electrochemical baths: It might be very reliable for car industry, but it should not really be used on high resistance steels as the ones used by latest generations tubesets, due to Hydrogen issues
-Phosphoric acid bath: I've asked Columbus about their tech opinion on how their tubes would react if using this technique (which seems to be used by a few builders). I thought it might be a great solution when reading about it, but lately some french colleagues had explained it's neither a "forever" solution and might need "manteinance" as the framesaver/oils choice.

Then, when I though that was all and not much else to do than keeping with the good old framesaver/oils spray can solution, I've come to another approach, used by UK motorcyle framebuilders (rara avis, but still some alive like Harris, etc), consisting on bathing each tube inside a weldable imprimation coat, then welding the frame and painting as "normal" ,leaving this previous weldable print coat inside as "permanent" protection. Anyone heard/tried something like that?

Thanks for your thoughts!

Cheers

[arregui]

Hi there,

I´m also interested on this issue. I´ve been using a phosphoric ac. solution (Phosphate Conversion Coating). When doing it correctly (with clean tubes at a certain temperature) it last in the inside of the tubes were theres no wearing. This is were i bought in in Spain:

Tratamiento superficies metálicas

They have lots of experience on the matter so possibly they have other ways to do it. The BEST thing about this guys is that they will make samples and test with whatever you send them (for free) to get to the best option for you.

I can send you una gran botella for you to make samples.

More options???


Saludos a todos!

Andrés

[Mike Mcdermid]

^^^^^ the man speaks sense

we looked into phosphating its as good as anything you will get some that need oil every six months some types may last 15 years under ideal condition just remember there are many flavours of phosphating and with it comes the good and bad the right choice will be working with someone for your application

the weldable stuff ive seen is 3m product if memory serves but as above its zinc based ,we used manganese phophating to increase bonded joint strength in steel (secret that was) that was pretty good

[Giff Holmquist]

Phosphating is the same things as used in guns. Not always a great solution for rest prevention. A better option would be something like a Nickel Boron or a Nitriding treatment. Nitriding is a treatment that actually changes the properties of the exposed metals. Again, both are used in the gun industry with nitriding being an amazing way to reduce maintenance and increase wear and corrosion resistance. Now, are they practical and offer a good ROI....probably not.

[Amaro Bikes]

Hola, Andrés!

Good to read you around here.

Basically, I just questioned myself all this things after the talk we had at "Cylco" event where you told me your phosphoric bath procedure, it sounded appealing to me but then some people told me it might not be permanent, etc, etc, so I got a bit confused, and this is why I emailed Adriana to know Columbus's tech opinion about this on their tubes.

Meanwhile, the weldable coats thing come to me and made me wonder if it was actually a "real" option for bicycle tubing.

But the most wise thing to do it sending some tube samples to the phosphoric bath guys and see what they propose, together with Columbus response it will be a good thought decission so to protect the frames best possible way.

What really intrigues me is how many different opinions are on same subject, from the "phosphoric bath is perfect" to the "phosphoric bath doe snot work". I can imagine is the same situation as with any other question, depends too much on each one's personal experiences, not to speak about the infinite experts populating the 10010101010 world ;)

Mike, to your experience, the phosphoric solution is better than any of those weldable coats, right?

Thanks all for your responses.

Agur! ;)

[Curt Goodrich]

Are you talking about stuff like this?-
http://www.bapspaint.com/docs/psheet...tron/P-226.pdf

I've used PPG DX520 phosphoric acid wash to clean out the inside of frames that are in for repaints. It removes any surface rust and leaves a black-ish finish. Allegedly it prevents rust for a while but I'd still recommend squirting in some frame saver. Whatever you do, consult your painter/powder coater before using something inside the tubes before the paint or powder coat is applied. If whatever you put on the inside of the tubes melts or ignites at higher temps this could be disastrous for the painter. Most wet paints are being force dried at 140-160F. Powder is melted around 400F.

[druptight]

Do you really warranty your steel frames against rust related damage? I would think regular maintenance, such as frame-saver-ing your frames, wouldn't be covered by a warranty and be the job of the frame owner.

[Mark Kelly]

What really intrigues me is how many different opinions are on same subject, from the "phosphoric bath is perfect" to the "phosphoric bath doe snot work".

At the risk of adding to the noise, some basic chemistry:

What a phosphoric bath does is converts some of the surface material to iron phosphate (FePO4). The iron phosphate film adheres extremely well to the surface but it is not a passive film the way say chromium oxide is, being quite porous, allowing oxygen to pass through and oxidise the surface underneath.

This porosity is simultaneously its greatest asset: the phosphate film can be used to hold and key another layer of material to the surface. In this case it is the presence of the other material, be it oil, wax or paint, which is preventing oxidation. The phosphate just holds it in position.

None of these secondary agents is going to survive welding.

[bastl]

At the risk of adding to the noise, some basic chemistry:

What a phosphoric bath does is converts some of the surface material to iron phosphate (FePO4). The iron phosphate film adheres extremely well to the surface but it is not a passive film the way say chromium oxide is, being quite porous, allowing oxygen to pass through and oxidise the surface underneath.

This porosity is simultaneously its greatest asset: the phosphate film can be used to hold and key another layer of material to the surface. In this case it is the presence of the other material, be it oil, wax or paint, which is preventing oxidation. The phosphate just holds it in position.

None of these secondary agents is going to survive welding.

+1 for this!
Phosphatic acid just provides a good prepared surface for the following rust prevention. It´s not rust prevention itselves.

And inventing/developing a rust prevention that survives welding and does not influence welding will make you a very rich man!

[Craddock]

What Mark said. Then for good corrosion resistance follow the phosphate wash with e-coat. This paints the inside of the frame at the same time as the outside, but you'll have to use large breather holes and consider the entry angle as it's a dip process in a bath of charged paint. Not easy to get the liquid in and out of a bike frame but I know of one manufacturer who does this with steel. Check compatibility of any further wet paint or powder with the e-coat chemistry.

[arregui]

Recently found about cataforesis (KTM - Kataforesis Madrid) or electrophoretic deposition (Electrophoretic deposition - Wikipedia, the free encyclopedia).

Not a welding survivor but an effective way to avoid inner corrosion. It great as a primer also.
Probably it will need some kind of chemical cleaning before the ionic bath.


Anyone doing this at home?

[abbeyQ]

A decade ago when I built big pressure vessels we had some kind of silver paint that we put on joints that were to be welded in the field. I have no idea what it was called but it settled out really bad so you constantly had to stir it. It also dried really quick with this kind of heat shimmer looking effect. I was told it was super expensive stuff but was never given a number. Our guys in the field would either weld over said paint with dual shield or 7018 stick rod, not sure how it would do with a low amperage tig setting.

Personally I think it's up to the owner to keep up with some basic rust prevention.

[Too Tall]

That's exactly ride Jason. Practically speaking anything that you are going to treat the frame with is better applied AFTER the painter has their way. The contaminants from such products and associated propellants blah blah blah are a nightmare.

That said (drum roll). NFS world headquarters is working on a frame protection scheme that is low toxicity, requires only a trigger spray to apply and non-flammable. Currently testing several versions.

I personally have used FrameSaver for ages and it kinda sorta works if you keep after it but I know we can do better and mean to do just that.

tick tick tick

A decade ago when I built big pressure vessels we had some kind of silver paint that we put on joints that were to be welded in the field. I have no idea what it was called but it settled out really bad so you constantly had to stir it. It also dried really quick with this kind of heat shimmer looking effect. I was told it was super expensive stuff but was never given a number. Our guys in the field would either weld over said paint with dual shield or 7018 stick rod, not sure how it would do with a low amperage tig setting.

Personally I think it's up to the owner to keep up with some basic rust prevention.