Originally Posted by deadforkinglast
A framebuilder friend of the bike co-op that I work at recently donated a box of welded but unfinished 1" steel threadless stems in varying lengths. Each of them still needs to be cut to make the clamps useful, then I need to find some way of finishing them to protect them against rust and general wear and tear. I've decided to make cutting and finishing these stems my project for the time being (I need to stop building bikes for myself!). I hope to make them sellable/useable items.
Does anyone know a good procedure for cleaning, prepping and finishing bare metal? I'd like to use a transparent finish, at least for the one that I'm putting onto my bike, because I think the bare metal has a distinct and unique look that would be fun to look down at for hours every day, but if that's not feasible, I would consider other options.
Solutions that can be implemented in/around my house would be ideal.
clearcoating bare metal isn't all that tough, I've done it for several chopper/custom drag bikes, but I usually had highly polished steel, and in one case, I clearcoated a frame and tins that had been color case hardened and engraved, like an old gun receiver, and was just breathtaking out in full sun.
I'm not sure the look your after, but,.....
your biggest problem is removing all the corrosion, then cleaning the metal, and then clearcoating it before it starts to corrode again, and have the surface somewhat presentable, as the clear will actually magnify defects in the metal.
I have shot several art projects where an artist had taken an angle grinder to a metal sculpture creating swirls and shapes,...once clearcoated it gets an almost holographic effect, which can be magnified by using a tinted clearcoat (kandy apple type paints)
you can use a typical metal prep solution mixed according to the directions, and then after it dries, you can wipe most of the zinc oxide off of the steel with a mixture of 50% distilled water and 50% isopropyl alcohol, then blow dry with compressed air, and then shoot the clearcoat immediately.
as far as which clearcoat you only have a few choices, and I would personally avoid any spraycan clearcoat other than the last one listed here, or you'll get MAJOR peeling in less than a week. (really you can use whatever clear you like, but these are the only ones I'd RECOMMEND.)
1) standard automotive urethane clearcoat
: great clarity (called "DOI" or depth of image) expensive, and you need a compressor, GOOD HVLP, or LVLP paint gun, and a place to paint free of ignition sources and with EXCELLENT ventilation.
2) GLISTEN PC http://www.por15.com/prodinfo.asp?grp=GPC&dept=6
this stuff is very special, and RIDICULOUSLY HARD TO APPLY,...I have well over 30 years behind a paint gun, and it took me no less than 6 tries before I had what I would call "professional" results, it just DOES NOT behave anything like a standard clearcoat. (if you get it, PM me and I'll tell you what I learned about shooting this stuff)
the good news is that after almost 12 years outside, my polished aluminum motorcycle tank looks as good as it did the day I shot it.
this should work over cleaned steel, and probably give the best adhesion of any of the choices, and remain the clearest for the longest time. I HIGHLY recommend this product, keeping in mind that you will be shooting SEVERAL test panels to get the spraying technique down, but still worth it for the incredible lasting clarity, and the way it sticks to bare metals, even chrome!
3) RM 2 component urethane AEROSOL clearcoat
exactly the same as choice #1, but in a special one use aerosol can, great stuff, and easier than making pop tarts to use. and before you go
at the $36 a can price, remember that a quart of the CHEAPEST urethane clearcoat on the planet will run you at LEAST $50 for the clear, hardener, and reducer.
true you could paint a dozen bike frames with a quart of clear, but you get the idea: no compressor, no paint gun, no mixing, no measuring, no mess yada yada.
just remember that whichever product you use, you MUST get that metal squeaky clean, and then coated before it starts to oxidize again, for the best longest lasting results.
let us know how it comes out (pics!
) and feel free to PM or post further questions to me, as I have probably more experience than most painters painting bare metal, which is not something the average painter gets to try very often.