Painting Basics

Im sure this has come up before, but I didnt find much in the search. If you know of a good post, let me know and Ill check it out.

Im looking for some info on painting the body. I have some surface rust, some areas of old paint that seems good and I can just paint over, and other areas where I sanded and primed it but it has started to rust through. Whats the correct way to prep and paint? Im not looking for a pro grade job, rattle can is just fine. I just dont want to rattle can it only to have to do it again because it keep rusting through.

Are there types of steel or nylon brushes that work well? Some that I should avoid? Special degreasers or some type of surface prep solution I should be using before I shoot on the primer?

Thanks for all your help!

 

You have to get rid of all signs of rust, get it down to clean old paint or bare clean, shiny metal. Any spots of bare metal need to be painted with a good etching primer (usually green colored) and then the sandable base primer over top of everything. I usually wipe everything down with lacquer thinner (very, very little on a rag -- too much will cause more harm than good) before paint.

If you leave any rust, even surface rust, it won't last.

There's tons of information out there on the Internet.

 

I understand the need to get to the bare metal if at all rusty, but what are some good methods? The rubber disk with the stick on sandpaper seems to be a wast of time for me, maybe Im just doing it wrong.

Has anyone used those nylon "cup" brushes or black stiff foam wheels? Are flap disc any good or are the flat layered sandpaper disc better? Or are there other products that work good?

Thanks!

 

Wire wheel or a flap disc is a little too aggressive for body sheet metal IMO. For frames it would be fine. I picked up an electric D/A sander and use PSA (sticky backed) 6" sandpaper. Depending on how much paint/rust/bondo you have to remove, you can start with 80 or 120 grit paper. If you have, or have access to a GOOD air compressor you can use an air powered sander. From your first post it sounds like you need to clean the rattle canned areas better, and remove the older paint to get a uniform surface.

 

You don't need to take it all down to bare metal, only the parts that require rust removal. For the rest of it, sand it with a sandpaper disc until you get a smooth, even surface. Areas that do end up down to bare metal need to have some etching primer and then do a sandable primer over everything to give you a good layer for the final paint.

I have used wire wheels to remove paint and it does work but then it requires additional sanding afterward to remove all the scratches. Don't waste your time with paint stripper, it will only cause you more grief. Sanding with sandpaper is really the best way to go, albeit slow and laborious.

 

I figured the wire wheel might be a bit agressive but figured id ask anyway.

I do have a good 80gal compressor, but whats the advantage of an air sander vs an electric one?

 

The problem is that the the top of the hood, fenders, and dash/cowel was sanded down to bare metal before and just rattle can primed. It wasnt bad, but its been sitting a few years since and the surface rust has come through. So now I want to redo it and paint those areas. The frame I already sand blasted and coated with POR15, so thats good for now. Its the body thats my concern.

Thanks for all your help everyone!

 

For the surface rust on old primer, just sand it until it's smooth and then prime again.

 

I do automotive restoration. I deal with rust all the time. You can deal with it mechanically or chemically. many times, its a bit of both. I would be happy to answer any specific question pertaining to rust or body restoration. Just ask.