Product application
The next step is to properly mix and apply the filler/putty to ensure proper adhesion and eliminate pinholes. Work any air pockets out of the material by mixing the product on a smooth, non-porous surface with a spreader using firm downward pressure. Using this same technique, apply a skim coat to wet the surface of the repair.
Sanding
Make sure your technicians keep the sanding process efficient by avoiding the two most common mistakes: using grits that are too coarse for the repair, and sanding too far outside the actual repair area
"Oversanding" increases the size of the repair and can put deep straight-line scratches in the repair area that will need to be feathered out.
When working with conventional fillers, technicians tend to start with coarse-grit sandpaper (60-grit or rougher). One of the major advantages of certain body fillers is that they can easily be sanded with 80-grit or finer paper, eliminating the need for coarse grit sanding. Some shops say they can go from sanding directly to the primer.
Inspection tips
Now that the repair is ready to go to the paint department, an easy way to detect pinholes is to use a light-emitting diode (LED) light. There are several hand held battery units that help identify pinholes. Fixing pinholes at this stage with a skim coat of premium pourable putty is much faster than wasting the material and time trying to bury them in primer. Simply hold the LED light at a slight angle above the repair and closely inspect the surface.
Tim McKinney is an ASE master certified collision technician and Evercoat's automotive training coordinator. He also has worked as a body shop manager and as a damage appraiser for a southwest Ohio insurer.