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Stainless steel coatings

Discussion in 'Bling and Appearance' started by nice2Bnaked, Mar 14, 2007.

  1. Ive stripped a feul tank and steel frame, and I want a bare metal finnish. I need to coat it in a clear to stop it corroding, but I also dont want it to look coated. Will as powder coater be able to clear it? I dont want it to discolour either... I got some clear-coat enamel from bunnings in a can, but Im not sure if it will be good enough. The frame is showing rust residue after just three days : (
    Some help would be apreciated.

  2. Try your local panel shop and see if they can blow on a couple of coats or auto clear.
  3. Well i will have to ask why?????

    Buy if you must i'd recomend using an automotive clear coat, preferably 2 pack.
  4. AFAIK, there are NO clear powder coats.

    Where does the stainless in the thread title come into it??

    Some have suggested clear coat... :-k

    So we're talking a pure barrier system of a one kind of coating to stop corrosion... :-k

    I can't attest to the barrier properties of a clear coat, but I don't think that they're that great without the other coats that normally go underneath it... clear coats provide toughness, sheen and UV protection - it's all the other stuff underneath that provides corrosion protections.

    So what you seem to be thinking about is plain (polished/shiny?) steel finish hopefully maintained that way with ONLY a clearcoat... and you want this on a road going, exposed to the atmosphere, stone chip, tank bag - jacket zip - belt buckle scratchable working environment... yikes, I think you're asking for a major headache.

    Steel naturally wants to corrode in the presence of oxygen and moisture - and it can happen relatively fast (3days in your case is slow - must be in the garage)

    An amazingly brilliant and perfect clear coating job will stop/slow this by the fact that it puts a barrier between the steel and the atmosphere, but no coating is perfectly impermeable - some are better than others, some that do a highly specialised (water tank lining for example), but generally coatings "breathe".

    But even if you assume clear coat is pretty good, any imperfection in the coating application, any thin coating thickness on a radius, any low coating thickness at a sharp edge, any knick, scratch or pinhole, or any contaminant at the bottom of a pit or salty sweaty finger print trapped under the coating... will ultimately promote corrosion to start.

    Even more basic than that, fundamental actually, is that I'm sure the clear coat needs a surface profile to key into and hang onto the steel, but that means you need a bright but dull surface... so the chances of a coating hanging on to a highly polished surface is very very doubtful. No adhesion means that the coating will simply peel off.

    Ever wondered why plain steel clear coated surfaces haven't been done before??

    Frame polishing and electrolytic coating in some kind of chrome/nickel is the way to go.

    I forget the name of the mob, but there is a mob who specialises in polishing bike wheels and frames to mirror finishes - I see them at track days and at the expos... I think you need to see them.

    Sorry to put a wet blanket to the idea.
  5. yeah tried something similar on a stainless uxhust dont do it. rusted away quicksmark, the paint was flame proof clear coat that did not need primer btw
  6. Normal clear coast won't cut it, it has very little in the way of body, and poor impact strength in a single coat system.
    There is a specific clear coat for this type of thing, I read about it on an automotive forum, although I don't remember any details apart from that it was quite thick, and there was a clear etch primer available.
    However, it is still not as strong as a proper paint system.
    I don't know about plating either, the electrolysis process can cause issues with a metal's properties, probably fine if it's a plain steel frame though.
    Which brings up option three, there are some very good chrome style films available that could be applied over a proper paint system.

    Regards, Andrew.
  7. Electroplating can cause problems even with plain steel - this is mainly due to the cleaning of the metal rather than the electroplating process itself though (specifically hydrogen embrittlement from phosphoric acid cleaning).
    Clear powder coating is most certainly possible, it's commonly used on alloy wheels and even as a final coat on BMW cars - it can most definately be used on raw steel too although proper surface preparation is absolutely essential. Although if you have the money nickel plating is definately the best way to go for a durable, shiny finish.
  8. JD, what kind of element/compound do they use in the powder for clear powder coating?? Interesting.

    I'm aware of Hydrogen evolution during the electroplating cleaning step, but embrittlement seems like a pretty remote possibility. You'd need to have a very high strength steel - not sure a VTR frame is that high a strength steel. If the temperatures involved are high enough H embrittlement might be possible... but you're more likely to warp the frame... eeek!
  9. The bikes a CBR600 f2 ('93) and I want the bare metal look so its, er.... Tough... I know, a bit lame, but I've always wanted to do a custom bike in bare metal, preferably a Harley, but thats for when I get some more $$$. Its going to be exposed alright, when Im finnished its getting some serious hours doing courier work. Its a budget priject, so I dont think I will be spending much on electro/nickel plating. The Idea behind the bike is toughness, not look-at-me shiny bits. If the frame does get surface rust, will it weaken it? Maybe thats an idea for the bikes look... The whole thing rusty... Hmmmnnn, that would look defferent if I excellerated the rusting process.... Oh well, going to put some serious hours into it tonight, removing all the paint and polishing the frame. How do other people polish their bits without corrosion?
  10. True, hydrogen embrittlement is really only a problem with case-hardened or high strength steels. But if you're not sure if it is a high-strength steel frame then you can't be certain that it isn't a high strength steel :p - so obviously you'd be taking a risk unless you found out for certain what steel has been used (and how it's been treated).

    As for the rusting question it will most definately weaken the frame since you're losing steel - worst part is that rust will tend to concentrate around areas of high stress where strength is needed most. This sort of localised corrosion can easily cause massive structural failure in a very short amount of time if left unchecked. So a deliberately rusty bike is definately not a good idea - you'd be far better off with a painted finish that gives the appearance of rust - which is easily done (ie coat of primer to protect the metal followed by an iron oxide pigmented paint).
  11. N2B, good luck with the project.

    You're opening yourself up to a world of ongoing work... but post up the pics - sounds interesting.

    No. But leave the rust to continue and you will ultimately get metal loss and pitting - both will weaken the frame and each pit could become a potential crack initiator if the stress conditions are right.
  12. For JD - agree with you. Just note, H embrittlement is not only a problem with case hardened components:

    ...which leaves me needing to correct an error in a previous post.

    Er, that would be my brain fart... I was thinking of high temperture hydrogen attack which occurs at high temps and high H partial pressures...definitely NOT an issue here.
  13. I'll post pix in my garage soon, before and after... Keep in mind that before we bought it, original owner got offered $400 for it by the Pickles Auction group. It was a seriopus heap 'O shyte.
  14. Yeah fully aware of that - that's why I said case-hardened or high strength steels. Both have high yield strengths and both are susceptible to problems - and this is why knowing both the steel used and how it's been treated is important (since even a low-carbon steel can suffer H embrittlement if it's been carburised).
  15. The mob I was trying to recall is:


    :? :-k ...The introduction of carbon into the surface layer of a steel that has a low carbon content. The process is carried out by heating the components in a solid liquid, or gaseous carbon containing medium. ... :? meh. ...bugger it... moving on.
  16. Yep - which increases the strength of the outer layer of that steel making it susceptible to embrittlement. Think of carburised steel as high-strength steel with a nougety mild steel centre ;).
  17. Sigh... a point of order then, which I was happy to avoid.

    You're earlier statement seems to suggest that a low carbon steel is not susceptible to H embrittlement unless it's carburised. Just don't forget that there are high strength low Carbon steels and they will happily Hydrogen embrittle in the right conditions - whether you carburize it or not.

    H embrittlement is an issue of high strength, not of carbon content.

    Carbon is not the only alloying element that will increase Yield and UTS.

    On the topic of a low strength CS with a case hardened/Carburised surface - what's the chance of the entire component suffering from H embrittlement once the lower strength "inner core" has been reached?

    Listen, this is way off topic nit picker stuff. No old CBR600 is going to have a case hardened frame... surely we're done now...
  18. Yeah I know I was simplifying things a bit with high-carbon=high strength but I was trying to avoid getting too technical. With case hardened components it's the outer surface that carries much of the load so hydrogen embrittlement doesn't have to penetrate far to cause problems - there's plenty of case studies of failure in carburised parts resulting from embrittlement. But you're right it's unlikely a motorycle frame's been carburised which is why I only mentioned it as more of sidenote (which is why the comments are in brakcets like this).
    Fairly sure the only use of HSLA steel use in motorcycles has been in the frames of Buells - everything else is just simple tubular carbon steel. I therefore didn't see a point in complicating the issue by mentioning HSLA steels since they haven't had many issues with embrittlement (due largely to the fact that their natural high corrosion resistance means very little cleaning is required prior to electroplating hence very little chance for embrittlement to occur). If you want to get nit-picky I'm fairly sure a CBR isn't going to have a steel frame at all - but the issues of Al alloys and powder coating/electrolplating has already been done on Netrider (fairly sure more than once).