Many collision repair shops overlook metal finishing, but it is an area where speed can be increased and cost savings generated.
Seven years ago, Evercoat developed a comprehensive standard operating procedure for metal finishing — visit www.evercoat.com/training.aspx. This process demonstrates how day-to-day techniques have an impact on a shop's productivity, customer satisfaction and profits. The program covers cleaning the repair area, paint removal guidelines, product selection and application techniques, sanding recommendations, and tips on inspecting the repair.This article examines how shops can use metal-finishing processes and products to improve productivity and save time and money.
Cleaning the repair area
Cleaning is critical. Don't grind off contaminants with the paint. Contaminants can be pushed into the repair when sanded or picked up by the sander and transferred to the next repair, so it's important to clean the entire panel to be repaired.
Start with soap and water and then use your paint company's recommended wax and grease remover. In addition to minimizing the risk of a failed repair, this process helps to visually identify the full degree of damage before repairs begin. Another helpful tip is to clean the adjacent panels that are to be blended to address any damage and avoid the last minute "what do we do with this?" conversation.Paint removal
There have been many changes to metals, including improvements in corrosion protection and increased use of composites. Make sure you use this latest technology to your advantage. If the vehicle manufacturers are going to incorporate new corrosion protection materials, use them instead of removing them. Choose materials that can adhere to these coatings, and save time while keeping the factory corrosion protection intact.
One way to do this is to use a DA sander with 80-grit sandpaper instead of a grinder with aggressive grits. Grinding can generate heat and cause the panel to warp during the repair process, and aggressive grind marks also may hold air and increase the potential for pinholes. Using the DA with 80-grit paper eliminates those risks while maintaining factory corrosion protection. If you must sand the panel down to bare metal, be sure to use a quality body filler that restores factory corrosion resistance.Surface preparation and product selection
After sanding, it's important to remove all dust. Dust tends to make the initial application of filler or putty want to "roll off" the repair instead of adhering properly. If using compressed air be sure that the air is not contaminated with oil or moisture.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.
