Painting an automobile is probably the most labor-intensive thing you can do to a car, even more so than pulling and rebuilding a drivetrain. For a paintjob to be exceptional, a certain amount of finesse and excruciating attention to detail is required, along with a large amount of patience. Combine the mental requirements with the ever-increasing prices of refinishing products, and you can see that there is a sizeable investment in the endeavor. That being said, we wanted to share with you some tips that we gathered while working with Rusty and Brian Gillis at Gillis Performance Restorations (Port Richey, Florida) on our '66 Mustang fastback project. You may find that they save time, or probably more importantly, help you obtain a better end result.
Try using a razor blade or other type of scraper to remove the paint. That's what Gillis Performance Restorations' Rusty Gillis said to us as he shaved the black paint off of our Colt of Personality project. The paint hadn't bonded well to the surface of the metal, and was easily peeled up with a blade. As the previous owner had explained to us, he didn't really know what he was doing with the modern paints when it came to mixing, and he was far more familiar with the lacquer paints of yore. The hazy finish was a sure sign of this. The paint came off very easy with our project, but as Gillis pointed out, sometimes it comes off in smaller chips, so make sure you have a face shield. You can media blast, but don't soda blast unless you know how to properly neutralize the surface afterwards, otherwise your paint may start coming off later on. Gillis always starts with the razor blade scraper and tries to remove the paint, leaving the primer.
The jury is still out on whether or not it is better to strip the car to bare metal or leave the factory primer as a base. For classic cars, taking it all off is probably the best route, as you don't want to lay thousands of dollars of custom paint on top of 40-plus- year-old primer. Late-model cars can get away with using the original primer as a base because it is generally of better material, and you are more than likely repainting the car's stock color.
If you have to strip it, start out with a DA or orbital sander and some 80-grit paper. If you find any body filler, step down to a coarser 50-grit. Gillis prefers a 3-inch mini grinder, as the single-action machine will remove the filler quicker, and allow you to get into smaller areas.
Clean the bare metal by using a wax and grease remover. Paint and/or lacquer thinner are generally bad choices. Gillis prefers to utilize SPI products, and in particular, its Wax & Grease Remover, using the #700 waterborne for clean metal. If you are painting over something that has had oil or grease on it, use #710. Also, don't use rust converters once the metal has been cleaned. Just get your primer/sealer on the metal quickly.
Gillis mixes his SPI epoxy primer in a 1:1 ratio with the 6700 activator. He waits 30 minutes before spraying two coats, with an hour of drying time between the two. Check with the manufacturer of the products you are using, as they will most likely specify an ambient working temperature, as well as a material temperature for what you are working on. As a general rule, Gillis makes sure the metal temperature is at least 60 degrees F when shooting the epoxy primer.
You need an assortment of sanding blocks in all shapes. Gillis uses various sized rolls of self-sticking sandpaper along with a host of blocks and/or tools to fit just about every shape. Keep in mind that all sandpaper is not created equal. Though the grit number may be the same, the quality of the paper and how it works varies among manufacturers.