It’s pretty exciting to see do-it-yourselfers attempting some of the more difficult aspects of classic truck building on their own these days, and bodywork and painting are prime examples. These tasks, which in the past have more often than not been relegated to experts, are ones more and more are tackling with surprisingly good results. But as with any craft, painting is an art that’s perfected by practice—kind of tough when as a hobbyist you paint maybe one vehicle a year.
So, it’s with this in mind that we decided to try and put together a bit of a primer (no pun intended) referencing some of the most common paint problems many of us have or will encounter during the course of any paintjob, jobs we’ve done, or will possibly do. Hopefully, the following information will help us novice painters identify, and with any luck rectify, some situations that would otherwise have us tearing our hair out or tossing our spray guns in the trash bin.
Prepping for Paint
In a future issue we’ll revisit body work and paint prep in a much more in-depth manner but let’s touch base on the obvious for the time being. As is the case with many aspects of truck building, proper preparation is key and, as you’ll see, plays an important part in causing or preventing many of the following examples. In a nutshell, any surface to be finished should be well cleaned before painting. If the surface is bare metal and the paint manufacturer’s instructions call for it, the surface should be chemically treated, as well. Use compressed air and tack rag to remove all dust and dirt—remember, no amount of primer or paint will cover up a badly prepared surface.
Today’s finishes are extremely complex and include both solvent-based and waterborne types, and most require the addition of solvents (thinners or reducers) to form the proper spraying viscosity. Others may simply require the addition of a second component at a prescribed ratio to obtain a sprayable consistency. The majority also have hardeners or other catalysts, which must be added to insure correct color match, gloss, hardness, drying time, or other characteristics necessary to produce a nice, successful finish. And please, always make sure you take the time to read the instructions and/or any specific finish material data sheets accompanying whatever paint and material you choose to use! And, again, remember that it’s never a good idea to mix materials from various manufacturers.
Once you’ve got your surface prepped and ready to be sprayed, the next step would be to know the type and color of paint your project requires—with this determined, follow the manufacturer’s instruction for preparing it exactly. If you have any doubts about how to proceed, don’t guess! Contact your paint supplier for help cuz improperly prepared primers, sealers, or paints will rarely produce a good finish and often cause huge amounts of heartache—believe me, I know from firsthand experience!
A major attribute which determines the sprayablility of paint and how much film may be applied is its viscosity—or consistency. Following the instructions on the cans will get you close, but for professional results you gotta use a viscosity cup. Unlike the old days when I used to just watch how the paint ran off my paint paddle, the advanced finishes of today need to be handled much more professionally. It only takes a minute and checking paint’s viscosity is a simple but very accurate way to measure its thickness. Viscosity cups are available anywhere that automotive paint is sold and they’re easy to use, too.
Always mix your paint in a clean, dust-free environment. Paint has a remarkable ability to attract dirt, and dirty paint will not only possibly muck up your spray gun, but it will also ruin an otherwise good paintjob. That said, make it a habit of always pouring paint into the cup or tank (if you’re using a pressure pot) through a paint strainer.