Bicycle Mechanics - bike paint?
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06-06-10, 05:30 PM
i hope this is the right section, so
i recently repainted my bike because of rust coming through. so i sanded the spots down and made sure to go over most of it so i wasn't painting above anything glossy. anyways i painted it with rust-oleum primer, then a flat protective enamel and finally a crystal clear enamel (all of them were spray paint) its been a day and it seems like the paint is really fragile (i can push my nail into it)
it seems like im missing something, is there something to harden over the frame?
Did you do all three coats in one day? If so, you didn't give the paint enough time to dry. Ideally, each coat should be dry before the next coat goes on.
Just keep an eye on it for the next week or so to see if it hardens up.
06-06-10, 05:42 PM
i did the primer and flat in one day then the clear the next day, im guess i did it to fast?
Paint dries in two steps. First it dries, so it isn't wet to the touch, then it cures, meaning all the solvent continues to evaporate slowly until it's dry and hard through and through. Many paints allow you to do 2nd coats after it dries but before it cures, then you have to give it plenty of extra curing time for the now thicker paint to reach it's full hardness.
If you can live with the blems you've put into is, set the frame aside in a warm dry place to cure for a few days. If you have an attic that would be perfect.
06-06-10, 08:07 PM
My brother in law runs one of the best body shops in my state. He studies and teaches car painting for the best.
He tells me that if you put on too much paint too fast to refrigerate the painted thing for many days and you get a better cure. When paint cures if it is warm, the top layers of paint exposed to the air cure first. The problem is once the top coat is cured the ones underneath never will. Of course many think the heat is good as it dries the top faster. But only the top,
if you put on the paint too thick and too soon over another layer. Try and keep it cool for a week if you can. Keeping the top coat cooler alows the underneath layers to cure before the top coats Don,t freeze it, around 40f is good. If the top if totally cured it's too late, but no harm in trying this anyway, except the time. When applying the paint the temps needs to be right also.
06-06-10, 09:13 PM
Rustoleum paint wont work in a bike, correction.. it does work but u need at least 6 months for that paint to cure. THat the paint is dry to the touch doesnt men it is cure and sadly you choose a pretty bad paint for your project. So what is happening is not a surprise at all, always happens.
What u have to do is to paint the bike using urethane car paint. Is the only paint that will hold fine besides powder coating. Peel the paint to the bare metal.. clean it using mineral spirits... get 1 or 2 cans u-pol primer, i would use white or super light gray. Prime the bike with that, sand imperfections. Get 1/4 of a galon or a pint of urethane car paint, is called base coat-clear coat in the color u want. If you want a perfect match of the color u need probably your best bet is ppg paint. There is some cheapo car paint that will work but forget that you will get a perfect match of what u want, assuming you dont have a spray gun and stuff, ask the guys to put the paint in spray cans, 3 or 4 might do it fine. Paint that thing, sand the imperfections.
Now the clear coat, u have to get urethane clear coat, if you put something else the paint could crack after a few days. Get U-pol clear coat, 2 spray cans and spray it really nice, get a mask also because that thing is super toxic. Sand imperfections again, polish with paint polisher compound to get all super shiny. Done.
06-06-10, 10:36 PM
Rust-o-leum and other high quality rust proof paints are fine for the average to good paint job. It probably won't be a show quality job; but unless your restoring for a collector or a museum; it's fine. It is imperative that you allow the coats to cure thoroughly before applying the next ones though. They will never be as durable as automotive paints or powder coating; but for the everyday hobbyist, they are great!!
06-07-10, 07:06 AM
I agree that the rustoleum takes ages to harden. Not the best for a bike frame. Not very scratch resistant. I did it twice.
I chose black because it is harder to see imperfections. I have touched them up with black nail polish over the years. The finish is not great, but you can't see it unless you get close in bright light.
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