"Primer is like the foundation of a house," says PPG Product Manager Jeff Griffin. "You don't want to build a house on sand (lacquer)-you want to build it on concrete (two-component urethane)."
To be honest, we weren't thinking in such ambitious terms when we decided to go to work on our errant '84 Z28. We were just thinking that anything would look better than the faded, cracked mess covering much of the Camaro's surface. Then again, we have high hopes for this Z, so if the job's worth doing, it's worth doing right. And so we set out to learn what goes into getting a car into primer.
Our talent for this project was Studio Auto Body of Glendale, California. Proprietors Robert and Jeremiah Becker have painted a number of CHP feature cars, and even resurrected one that was sandwiched in a traffic accident ("The Mojo's Workin' Revisited," Sept. '05).We started with the basics, specifically, why do we need primer?
"Paint doesn't stick to bare metal like it does to primer," responded Jeremiah. "Primer is also the last layer of body filler," he continued, "but it mainly helps the paint stick." So there you go: Primer is part of the bodywork phase, but it's also part of the paint phase-the foundation we mentioned above.
The biggest issue facing our Z was the cracking paint. This California car even had surface rust in several places. "If the paint's cracking," Jeremiah told us, "you have to get it all off." This car vividly illustrates an important thing to remember when laying down a primer coat: You can't leave anything beneath the primer that might pop up and cause a problem later. That lesson taken to heart, we asked for a few other primer tips:
Jeremiah's Tips* Take off as many parts as possible. You want to sand and prime everything that you can.* Prepare the surface before body filler. Everything must be properly sanded and degreased before application.* Prepare the surface before primer. Again, everything must be properly sanded; using lighter-grit paper leaves fewer scratches to be filled.
You notice a theme? The words "preparation" and "sanded" figure prominently here. Jeremiah and his ace bodyman, Jose Garcia, took three days to get our Camaro into primer, and very little of that time-less than an hour, we'd say-was spent actually spraying primer. The rest of the time was spent preparing the car for the spray, and the bulk of that was spent sanding. Sanding, we came to learn, is crucial to laying down a good coat of primer, and for several reasons.
It's important, of course, to eliminate cracked paint and clear, as well as surface rust, so there's no nastiness left behind to ruin the paint. Careful sanding is just as critical to the bodywork. "If it's not sanded right, the filler won't stick," Jeremiah pointed out. But remember this: Primer is also filler. "The goal is to put a nice thick coat of primer on it, filling the scratches and high and low spots," Jose added. Remember those scratches. Sanding smoothes a surface but also creates minute scratches that must be filled. As we'll show you, minimizing scratches by using finer-grit paper when possible saves work in the future.
And what does that future hold? We will be painting this Z-but not yet. Truth be told, we've got a pile of go-fast parts we're dying to try out before we make it look pretty. So we're gonna drive it in primer for a while. "I don't recommend you do it for too long," Jeremiah cautioned. "Primer is porous, and it can crack and get moisture in it." So we'll be limiting our exposure to the elements.
There will still be a bit of primer work to do before we lay on the new hues. "We'll use a long-block with 150-grit paper on it to reveal the high and low spots," Jeremiah shared. "It'll get another layer of primer to fill the low spots, more sanding, then we'll wet-sand it with 400-grit." So there's a decent chunk of work to do. On the other hand, we've done the important prep work, laying the foundation for a high-quality paint job. Here's how we got there