I once heard a new paint technician tell his friend that he loved painting, but he hated sanding. Well, I don't think that any of us would list sanding as the task that we most look forward to when working, but we must also face the fact that if a good paint job is 90 percent prep, then sanding is one of the most important jobs done when painting a vehicle. In fact, sanding is 30 percent of paint labor (Fig 1). That said, like everything else in the collision industry, the faster you can get it done, the more profit that can be made. Let’s take a look at some techniques that help speed the sanding process.
Washing and cleaning
One of the first steps when prepping a vehicle for paint is washing (with soap and water) and cleaning (with wax and grease remover). This important two-prong step will prevent a great deal of problems that may crop up later in the process. I say may because some painters might get away with painting a vehicle that is not clean, or they just may not recognize that some of their problems stem from not properly cleaning the vehicle before painting. Besides the obvious fish-eye problem, other problems such as dirt in the paint, missed defects and poor adhesion can all be traced back to a poorly cleaned vehicle. Some look at this step a waste of time, while others just overlook the importance of the process. But painting over a vehicle that is not properly cleaned only leads to problems later in the process.
Both “prongs” of this procedure are critical. In the soap and water step, pH balanced soap is used to remove contaminants over the entire vehicle, including the door jams, under the hood and the deck lid. Once the entire vehicle is soap-and-water cleaned, next the technician should clean the area to be painted with a wax and grease remover that is compliant with your shop’s paint system and the regulations of your area. This cleaning removes the contaminants that were not soluble by soap and water. The vehicle can be blown dry following the cleaning process so that the next step, sanding, can start immediately. A hand-held air amplifier that is used for waterborne paint drying works very well to dry the vehicle (Fig 2).
Inspecting the area to be painted is vital to find any defect that must be corrected before initial prep of the paint area. This inspection can often be done while either washing or cleaning the vehicle. Look for things that may have been missed by the tech doing the body work, as well as for any defects that the estimator missed. If any are found, notify the estimator so a supplement can be written. By doing an initial inspection while washing the vehicle, the technician can make a repair plan at that time. During the inspection process, the tech should also retrieve the paint code and write it down on the work order, if it is not already there. Having the paint code early in the process and checking that all the needed supplies are available for the job will eliminate wasted down time later on. If some supplies must be ordered, the job can proceed with the prep while the order is shipped in. Before we start sanding, let’s first look at the way abrasives are graded so we can choose the correct one.