I have a Linus Roadster and it got scratched moving cross country. I love this bike and want to touch up the paint job. Has anyone had experience painting over scratches on bikes? Should I bother? Thanks!
My trick is to find nail polish that roughly matches the finish. It's easy to apply, quick to dry, and will prevent rust and oxidation for quite a while. It's not a perfect finish match, but there are quite a lot of colors that come close.
If you can't find an near-perfect match try mixing two or three colors. Just remember the basics; with few exceptions all colors are derived from shades of the primary colors (red, yellow & blue) and black and/or white, e.g., orange can be derived by mixing red and yellow. Then you've got glitters and iridescents (whole different ballgame). But nail lacquers can be picked up at pretty low prices and if you're not good with mixing colors find a friend who is. You should be able to get a near-perfect match! One last thing, avoid mixing brand-to-brand if possible; otherwise you may have adhesion problems.
It would have been better if you could post some picture of the scratches on your bike to help us understand the depth of the problem.
Anyway, you can use either spray, nail-polish (quick and dirty), or actual wall paint (if you have any or nick it from the neighbours' :p ). however, if you have a lot to paint on, do it a little bit at a time. But if you use your bike once in a while, you can just do all the painting at one go.
The cheapest option is to get the nail polish. However, the colour would go off soon enough depending on weather conditions. Also, if you buy really cheap ones from Pound shop (or 99 cents stores if you are in the US), they won't last long. But, as I said, they are the cheapest and quickest option.
See this on Amazon. They should work too. The decision is yours.
Chips that are deep enough to show bare metal should be primered prior to paint. Chips that are not treated can cause more paint to flake off. The frame can start to rust and loose even more paint. While aluminum won't rust it can still corrode if exposed to road salt. I have had success with Testors brand toy model paint. I get a color as close as possible and custom mix to match my bike. If the blue isn't dark enough I add some black, if it is too dark I add some white. It is mixed in small amounts say six drops of blue and two drops of black. You can then dab it over the chips with a cotton swab or small artist brush.