Painting a Car at Home Part 1: Preparation, Preparation, Preparation

Step 1:

One of the first things to be done is to decide whether to paint over the existing finish, or strip the car to bare metal. Our car had issues: It had already been repainted at least once, the finish was peeling away, and we had ripples everywhere.

Past experience has taught us that when the paint and bodywork are this bad, it’s usually best to strip the car to bare metal. That step adds a lot of time and some cost to the job, however: Not only does stripping the paint take 10 to 20 hours, but usually some bodywork will also be required. Nonetheless, we didn’t want to do all of this work on a poor foundation, so we went back to bare metal.

Step 2:

We chose to strip this car with 36-grit, sticky-back sandpaper mounted on an air-powered, dual-action sander. Everyone has opinions regarding paint stripping methods. Here are ours:

• Chemical stripping can be a time-saver, but it’s really important to keep the potion out of cracks and seams or it will leach out later–perhaps even after the final paint is laid. We’ve also found that some paints are easily removed with chemicals–and some are not. We’ll usually test the chemical stripper and see if it will speed up the process. If the chemical stripper is the answer, we’ll use it on the larger areas, being careful to keep it away from the cracks and seams.
• Abrasive blasting-sand, soda, plastic media, walnut shells and so on–can also save a lot of time. However, this method seems to work better on disassembled cars because the media will find its way into every corner, making final clean-up difficult. There is also the risk of a ham-fisted operator warping and damaging bodywork-work with a trusted firm.
• Hand stripping with sandpaper is slow and dusty, but pretty hard to get wrong. The key is to use quality abrasives and change them often. Dull abrasives don’t cut paint; they just heat it up and make it harder to sand off. We use an imported air-powered, dual-action sander and start with 5-inch, 36-grit paper. Some people prefer 36-grit, others prefer 80-grit. We use 36-grit first and then polish the car with 80-grit once all of the paint is off. We’ve found this is faster and uses less abrasives. We used about $50 worth of sanding discs to remove the paint from our E30.

Step 3:

Like most 30-plus-year-old cars, our E30 had its share of road rash. The left-rear quarter panel had a light crease below the body ridge plus a small dent above it.

Step 4:

After stripping away the paint, we used a body hammer and backing dolly to lightly bring the crease and dent closer to the proper shape. The 15 minutes spent on this step probably saved us about an hour of extra time on filler work.

This also helped to keep the filler thickness to a minimum, reducing the chance of long-term issues like shrinking and cracking.

Step 5:

Now it’s time to share our opinions and methods regarding filler. We’re expecting some e-mails and rants with alternatives, which is fine. These methods have worked well for us in countless repairs. Before we mix up any filler, we prep a spreader by giving it a clean, semi-sharp edge with 600-grit sandpaper.

Step 6:

We use a quality, name-brand filler. We prefer the lightweight fillers, as they just seem easier to spread and sand. We’ll mix that filler with a paint stick on a piece of cardboard–usually about 6×6 inches. Make sure that both are extremely clean. There is nothing more frustrating than running into some hardened filler because a dirty tool contaminated the mixture.

Step 7:

We use a separate paint stick to mix the uncatalyzed filler in the can. We never use a stick that has been near catalyst, as it could contaminate the raw filler. We then use the same stick to put a few dollops of filler onto the cardboard.

Step 8:

We then lay a bead of catalyst on the raw filler, following the mixing directions on the label.

Step 9:

Using another paint stick, we thoroughly mix together the raw filler and catalyst–about 2 minutes should do it.

Step 10:

We then use our prepared spreader to apply the filler to the car in long, smooth strokes. We attempt to get the shape very close to the final profile needed. This saves us a lot of time sanding and re-applying filler.

Step 11:

We usually get about 10 minutes before the filler “kicks.” As soon as we’re done spreading filler, we clean our mixing stick and spreader with a paper towel to remove as much filler as possible. While this may seem overly compulsive, we do it to avoid having pieces of hardened filler flake off during the next application. We also tune up the spreader again with 600-grit sandpaper. After it has “kicked,” the filler looks like this and is ready to sand.

Step 12:

We start with an 80-grit disc on our dual-action sander. The first pass or two will quickly clog and dull the disc, so we’ll install a fresh one before we continue. We change discs fairly frequently, feeling them to get a true read on their condition: A sanding disc will sometimes look usable, but will feel dull. Sharp abrasives cut the high spots and help flatten the panel. Dull abrasives just follow the high spots and don’t do much cutting. End result? Ripples in a panel that should be fairly flat.

Step 13:

We only use the dual-action sander for rough finishing. Then we’ll move to a sanding block. The longer the block, the better. For this panel, a 12-inch block with 80-grit paper was the best fit. We used some crosshatch sanding patterns to identify low spots that would need more filler.

Step 14:

After about four cycles of “rinse, lather, repeat’–reapplying filler and then sanding it back–we ended up with a panel that was ready for the next step: high-build primer.

Step 15:

Multitasking: While the filler is hardening, we’ll continue to disassemble the car. We prefer to remove parts rather than tape them off.

Step 16:

Given that our windshield was cracked and its seals were weathered and dry-rotted, we decided to pull the glass. Since we weren’t reusing the seals, we cut them away to make the job easy for one person.

Step 17:

We went around the whole car repairing dings and minor dents until we had it ready for primer. To keep out the dust, we taped off the interior and engine bay.