In my training classes I am asked frequently, “Is drilling a requirement for a good windshield repair?” The answer is no. Drilling is not a requirement.  As a matter of fact, if you can refrain from drilling a pit, the repair will appear better after the process is complete. Not drilling leaves a smaller, less noticeable pit.

You should drill the glass for one reason only. Drilling opens the pit for resin to flow freely.  Sometimes when the break is old, the pit is plugged by debris from the roadway, from car wash wax or other debris forced into the pit by the wipers. This plug hinders the flow of the resin and should be breached or removed to properly complete the repair. Some drill out the plug and others use the edge of a straight edged razor blade to pick out the plug.

I have witnessed techs attempt to drill down to the lamination to fill the break better. Some have said that is what they were taught. Do not do this! The fact is that if you drill all the way down to the lamination, the windshield’s safety has been compromised and it should be replaced not repaired.

The part of the windshield that offers the occupants the greatest barrier for safety is the Polyvinyl Butyral (PVB) interlayer. If it is punctured by hitting it with a drill bit, the PVB is no longer a restriction to ejection. It would fail at the puncture.

The proper procedure is to first use the razor blade edge to pick out the plug. If that fails, then drill the pit only to open it up. Never ever go down to the laminate. Just peck the drill bit into the pit until open and only penetrate less than half of the first layer of glass. Once that is accomplished, the resin will flow nicely. If while you are drilling, and a string of plastic comes up the drill bit, you have gone too far.

Please, DO NOT over-drill.