Clear coat, bluing and other 'see-through' processes

Hey CFF, I’m looking for resources and experience with clear coating raw metal frames.

I’ve fillet brazed a frame that I want to leave some what raw but I also want to protect the frame from corosion.

I’m interested in hearing from people who have experince with any related proces.
How well does it last? Any resources I can lookup?

Also very interested in hearing about clean up/prep methods. I did some pneumatic wirebrushing and that did not make things prettier…

Clearcoat and cold bluing are fragile finishes. Just let it rust. You’ll be ready to make another one long before it becomes an issue

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Here is my commuter after riding year round for years, through many snowy and slushy winters and rainstorms. The only thing on it is a layer of clear Rustoleum spraypaint. As you can see there is some discoloration of the tubes but it’s not exactly rust, as you’d expect from regular steel. No orange flaky stuff.

So I don’t think you really need to worry about rust, from a structural perspective.

One interesting thing is that I used different brands of tubes to make this (and the rear triangle is from a Surly LHT). The top tube, Tange, did oxidize more than the down tube (straight gauge 4130).

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I had my full suspension frame clear coated without any abrasive prep so you could see the welding discoloration and it’s held up surprisingly well. Minimal rust underneath, some chipping on the rear triangle. Definitely doesn’t adhere as well as a typical powder coat job but if you blasted the frame first that would help

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Seattle builder Alistair Spence used a System Three epoxy on his first couple of bikes and it held up well for years before he decided to switch to powder coat. This is my favorite, where he sharpied in all of the frame dimensions:
https://www.flickr.com/photos/duncancycles/albums

I know that he called System Three to ask about this use and they said it would probably work well as long as it wasn’t exposed to a lot of UV. UV isn’t a big problem in Seattle.

I spend a lot of time around boats and varnish is often used over epoxy for UV protection. The varnish would add a yellow/gold tint though. It might be interesting to try the combo on scrap tubing.

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If you want the rusty look, you can either get some etching compound/lemon juice/whatever and rust it a bit, or just let it get rusty, and then coat it with Penetrol (paint additive you can get at any paint store). Got the trick from a rat-rod buddy. It will seal the rusty parts really well and then you have a cool came-from-grandpa’s-barn look that will hold up well.

In terms of clear over clean metal, I have never found anything that is super reliable. Powdercoat is ok, but adhesion is mediocre unless you blast/prep the surface and then you lose the cool oxide rainbows.

-Walt

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Hydrogen peroxide mixed with vinegar and a pinch of salt is my preferred ‘forced rust’ mixture.

Sand blasted then rusted -
image

Not sand blasted then rusted -

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I’ve also done a bunch of black oxiding on frames and parts. It works well, and adds a lot more depth then just clear over raw.

I use a blacking agent from Caswell Canada and then clear over it with Montanas clear coat. I’ve had mixed results for longevity, and warn people of this before hand.




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I tend to go with “too lazy to paint or wash bike, ever, for years” but those look great!

-Walt

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I’ve done liquid clear coat, coldblueing + clearcoat and yet to do powder clear with the new to me powder oven.

Filet brazed frames and clear coat are a ton of work if you want that perfect glossy finish IMO.
Tig welded frames are easier as you juste have to degrease properly.
Some of them stayed surprisingly rust free for a long time…

Blueing was very average, I used some french coldblue that should have been black but it ended up more brown-ish and really inconsistant depending on which type of tube it was on…even with good care and proper cleaning afterward, rust spots appeared rather quickly under clearcoat

( I’ll try to update with pictures and process later)

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I have a frame that I fixed where the bare parts are coated in boiled linseed oil and then I warmed it with a torch. Since then, I have read you should go hotter and it will blacken. I have seen furniture done that way and it looks nice. I don’t think it will anneal the frame, but it might be close.

My road bike is uncoated, all I did was wax it. I intend to get it powder coated any day now. It’s a little rustier than I would like, but not too bad.

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Parkerizing would be a fun option. I’ve been hanging on to a gallon of phosphoric acid for years. I got this from a laboratory “spring cleaning” event in hopes that I would one day make some home brew Parkerized bike parts. You can get manganese dioxide from pottery supply places very economically and this mixed with the acid and some iron filings, heated up, is supposed to parkerize steel. Still haven’t tried it yet.
Wouldn’t be great to do a whole frame due to the difficulty of dunking something so large in a heated vessel, but I was thinking it would be great for a fabricated chromoly crankset since it’s so durable.

Parkerized finishes are very durable and very porous. The finish doesn’t inherently seal the substrate against corrosion, but because it’s so porous it retains oil very well which does seal the material. And it makes it slippery. This is only reason it is so popular with firearms with all their sliding parts.

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Years ago the first REEB steel frames were clearcoated (powder) and while a good marketing strategy to get eyes on bikes i’m sure their customers have all repainted their frames by now. Unless you like it slowly rusting from the inside out.

I clearcoated over raw one frame in 2014. It was for a friend and I warned of the likely issues even for a Colorado frame. He likes how it’s “aged” over time…wish i could find the pictures. After a couple of years he got spiderwebbing rust under the clear and some worse rust alone the sharp edges like the BB, HT and ST collar. If you google Groovy Cycleworks, Rody posted some photos of a frame he clearcoated, after a year in the midwest it looked awful.

Looks cool at first and if your powdercoater is very careful handling it after wiping with acetone it could last longer but it just doesn’t adhere to the un-blasted steel very well so rust is inevitable. I love Ti frames, i can weld it and build it up right away. Paint and powder is cool but it’s so nice not to have to.

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I am curious how Mone does their finish, and how it holds up. It looks pretty cool.

Im sure the Fab’s in Taiwan have access to more industrial cleaning and coating processes, I wonder if the finish holds up better.

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I believe mone uses a manganese phosphate acid process. I’ve used some patina that we have at work. I applied it cold, when applying hot it changes the bronze immediately. This was an experiment, some areas I let darken more than others. I didn’t take much care after I rinsed the patina off, the rust that is showing up could be avoided. I’m unsure if powder coating after would be feasible. I still need to mess with it more.



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Thanks for all the replies! For now I’m just riding it with no coating. Will put in some internal coat asap to keep it safe.
Might try some tonkin varnish at some point. It’s a linseed based varnish mostly used in woodworking but it’s also recommended for metal and is supposedly quite environmentally friendly, at least way more so than powder coat I guess.

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A basic rattle can clear will keep it clean for a couple months while you suss out options.

There is a product you can apply which is a clear adhesion coat before you lay down an epoxy clear coat. My painter used it on the show bike from last year and it held up really well.

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What kind of conditions will the bike see?

I cold blued a frame (Birchwood Casey) and then oiled it with Gibbs lubricant (a hot rod trick). Still holding up fine, but this bike doesn’t see much water or weather.

If it does get a little surface rust I just remove it with a fine scotch-brite and oil it again.



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Do you use the black oxide gel or liquid from caswell? I wonder if the sealer in the kit is oil or water based? Knowing which would potentially determine what the best clearcoat option would be