I'm going to paint some engine parts black on my motorcycle. They are aluminum parts.
Which sandpaper should I use to ensure it doesn't show under the paint that I've sanded the parts?
I tested a bit with 360 grit sandpaper, but I don't think the surface became completely smooth. I'm worried that the surface won't be fine/smooth enough before painting.
I think you need up to at least 1200, preferably 2000-grit wet sandpaper so it doesn't show through. But there are several steps so it doesn't take forever, so if you've started with 360 continue with 800, then 1200, and finish with 2000.
If you are going to paint, 520 grit paper is sufficient; going higher is pointless if you're painting. If you go above that, we start discussing polishing, and that's a completely different matter, as you then gradually move up to 2000 or higher.
Forgot something 😳
If for some reason you had to start with, for example, 120 due to oxid or needed to even out surfaces, then you need to step up the grits until you reach 520.
I'm not a painter, but I've seen many professionals at work, and I've never seen anyone apply paint directly onto a metal surface. An initial finish on the metal surface, possibly filler and sanding, then a round of primer, sanding, possibly repeating, then primer, wet sanding, only then paint, and finally "topcoat."
Firstly, it's likely just a heck of a job to get a good enough finish on the bare metal surface, and secondly, it's probably about adhesion and protecting the surface against oxidation.
Most professional paint shops have sandpaper in the grit size you need. How are the surfaces today, lacquered, unlacquered, anodized, or powder coated? What finish do you want, matte or glossy black? Unlacquered surfaces need an etching primer before you apply the base coat. Don't forget that it should be 2-component paint, you can find everything you need on one of the websites that sell 2-component car paint in spray cans.
Have you painted before? Spray can or spray gun? Practice on a lot of scrap pieces before you tackle the bike. A bad job is worse than leaving it as it is. There’s nothing worse than poorly painted details on a motorcycle, and it's even worse if the paint starts to peel 🫣
Most professional paint shops have sandpaper in the grit size you need.
How are the surfaces today, lacquered, unvarnished, anodized, or powder-coated?
What finish do you want, matte or gloss black?
Unvarnished surfaces require etching primer before you apply the base coat.
Remember it should be 2-component paint, you can find everything you need on any of the sites that sell 2-component car paint in spray cans.
Have you painted before? Spray can or spray gun? Practice on a lot of scrap pieces before you start on the bike. A bad job is worse than leaving it as it is. There's nothing worse than poorly painted details on a motorcycle, and it's even worse if the paint starts to peel 🫣
It's the silver surfaces in the picture in post 1. Everything except the gear lever.
