MTBUK

I've got a used big box MTB that I thought I'd restore and upgrade for fun (first bike as an adult). I sanded the frame back to bare metal in parts that needed it and fine sanded the old glossy coat so it was all smooth and no bumps. I noticed that the areas that were bare metal had a kind of cracked looked after spraying, almost like it had been embossed with a leather grain.

I've stripped it back again, washed it down and ran some nail polisher remover over it to take off any excess grease but I'm a little cautious to use the rubberised spray again. Maybe I'll stick a primer over it first but I'm wondering if maybe I've missed grease spots and/or it needed a primer?

FiftySix

I have no advice on your paint. However, after you've degreased with acetone, try isopropanol or automotive brake cleaner to do a final level of degreasing.

Brake cleaner is fantastic at it, but expensive compared to alcohol.

MTBUK

Thanks! I'll give the break cleaner a go!

Ironfish653

I found that with the rubberized spray coatings like Plasti-dip, it’s best to build up at least three, if not four light coats, like 50% coverage, letting each one nearly dry, before going to full-coverage coats.

This stuff doesn’t like going on heavy, and too much at a time makes that leathery look you experienced.

DrIsotope

The list of paints that can be successfully applied over bare metal is relatively short. Should be primed. Self-etching would be good here, as the frame is apparently part bare and part paint.

coffeesnob

Good advice. I plasti dipped the wheel covers for my car and put on about 4 light coats and then a little bit heavier on the last one. Shake that can really good and dip can in warm water if it is cold.

phughes

Skip the brake cleaner. Use lacquer thinner. That is what we have always used to prep areas on cars before painting. Much cheaper than using brake cleaner. Wear gloves, and apply with a rag. It will evaporate almost instantaneously. And I will agree, prime the frame first. If you are looking for a nice smooth finish, prime, then wet sand, then prime again, then wet sand.

Ironfish653

I agree, you get better results if you’re covering a uniform surface, but these kinds of coatings are designed to cover things like damage and chips in the base surface.

If you’re using ‘rubberized coating’ like Plasti-dip, the whole point is that it won’t stick to smooth surfaces, so it can be removed. That’s why you have to do so many partial coverage layers, to build up a ‘web’ for the thicker ‘build-up’ layers to stick to.
Like the OP found out, it doesn’t like it if you put it on like spray paint; if you put it too heavy, too fast, you get a particular kind of poor result.
Unlike paint, you can’t sand it down between coats.. You have to remove it, which is difficult at best when you haven’t got it thick enough to be peelable yet.

CliffordK

I'm a little surprised about using a rubberized paint, although I've heard that "bedliner" is tough.

You might go to your vendor to find priming recommendations.

If you wish to send out, or you have the facilities, powdercoating is supposed to create a good durable finish. Slightly softer and thicker than paint. But, it has been successfully used in the bike industry.

MTBUK

It was an absolute pain to remove! I decided to skip this paint for now, I think I need to practice a little as I certainly did use it like spray paint. It's great stuff if you can take your time.

I since took a primer to the frame and I've noticed what looks like an area I've not sanded so it looks like a raised area. Should I sand these areas back as there are only a few patches or will multiple layers cover this? I only had time for one coat.

Thanks for the advice so far!

Troul 

Take those areas back. Spray afterwards.

MTBUK

Every day is a school day

bobwysiwyg

How true!

Bluesfrog

The lacquer thinner is the best idea to clean after sanding. DON'T use fingernail polish remover. There is an oil additive to it. Be Well. Bluesfrog

MTBUK

Well I sanded the errors out, gave a light sanding to the rest of the bike, sprayed down with Elbow Grease (the best degreaser ever!), washed off and resprayed with some matt black and it looks brilliant! I'll post up a pic tonight.

veloz

If covering a frame in plasti-dip, you don’t need to sand. A good cleaning using a degreaser is fine. We’ve coated several frames in plastic-dip with good results. It can be peeled off but takes patience. Best part about it is easy touch up. Worst part: cranking down hard to mount on car racks can damage it. Holds up well to outdoor storage through winter and summer. Metalflake colors with their clear coat look great.