How to Protect Your Car Project With Primer

The Easy and Cheap Way

Car painting
simazoran / Getty Images

Note: To all professional body and paint guys, you should turn away now. What you are about to read will shock and possibly pain you. This is in no way supposed to be a substitute for a proper job done in a proper facility. But it is an alternative.

This primer method is not intended as a base coat for a proper paint job. It's a working layer intended to protect the car from rust and other contamination during a time of dormancy.

The Cheaper Primer Alternative

Primer paint supplies
Matt Wright

If your car is ready for a coat of protective primer sealer, you have no doubt been doing quite a bit of bodywork. Even a small section of body filler needs to be protected from the elements while you get the rest of the car's body ready to be painted. Sometimes you need to take a break from the progress of your work, too. Leaving bare metal exposed to weather can put your restoration job into reverse. Surface rust sets in almost immediately with even a small amount of moisture in the presence of a bare metal surface.

A good coat of primer will help prevent damage to your metal work in between work sessions or if your car has to sit dormant for a time while you gather free time and funds to keep the job moving. You may think that you have to take your car to a body shop to have a professional layer of primer sealer sprayed over your ​properly prepped car or truck body. Okay, technically you should, if you can afford it. But for the rest of us, there are alternatives.

We have a friend who has restored and repaired a number of cars himself on ridiculously tight budgets. When he has to move one of his projects aside for a time, or if he is putting it into storage to resume work when he has, well, time and funds, he uses Rust-Oleum oil based primer/sealer to protect his car's body. It comes in only a few colors, and you can buy it at any home repair store by the quart of the gallon. Read on to see how this alternative works.

What You'll Need

  • Rust-Oleum Oil Based Primer (may as well buy the gallon)
  • Acetone
  • Air Compressor set to 32 psi
  • Paint mixing cup
  • HVLP compliant spray gun

With all this stuff together, you're ready to get busy.

Body Prep

Before we get down to the business of actually spraying, we need to be sure your car has been prepped at least partially. The Rust-Oleum product is very forgiving, and it's not a permanent part of your car's finish, so you can be a little looser than you would need to be in a real paint shop. The main part of prep that you need to perform is cleaning. If the car's surface is not clean, you will have problems with the paint not sticking to the car body. Wash the body and allow it to dry fully, the longer you can let it dry, the better. Once completely dry, apply some mineral spirits to a cloth and wipe the car down to remove any residual oils or cleaners that may be on the car. You don't need much, just enough to dampen the cloth.

Mixing Paint (Primer)

Rust-Oleum has prepared this primer formula so that it can be thinned down and sprayed using an automotive type paint sprayer. We prefer the gravity feed sprayers, as does this backyard painter. Mix the paint with acetone using a ratio of 1 part acetone to 5 parts paint. This formula seemed to work well and is what our guy uses regularly. You can mix as much or as little of this paint as you want, it's not catalyzed so the mixture won't go bad.

Spraying the Primer

Spray primer
Matt Wright

With your paint mixed and your gun loaded, you are ready to paint. Always test your spray pattern on something like cardboard or a neighbor's car before you start painting your vehicle. Don't get too picky with the paint gun adjustments—you're painting with Rust-Oleum, after all. When you get a decent vertical spray pattern, you can have at it. Remember to practice a 50% overlap between strokes. This means that when you paint one horizontal stripe, the next stripe under it should overlap half of the first stripe, and so on as you work your way down. This will minimize any visual striping when the paint is dry. One coat of this stuff seemed to be enough, but you can always add another if you want it to look better while it's in storage.