by Bob Beranek
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I’m dedicating this post to “setting the glass.”

What exactly is meant by setting the glass? Setting the glass refers to placing the glass into the opening on the vehicle’s body where it is meant to fit. Some glass parts are adhered to the frame (pinchweld) and others are mechanically fastened and attached with nuts and bolts. The adhered part uses adhesive to bond and seal the opening from weather related issues, while the mechanically attached parts use a sealant.

Proper glass setting is imperative to sealing and bonding success. The amount of clearance in many cases, from top to bottom and from left to right are less than ¼ inch. The most important and difficult part to set and manipulate is the windshield. Due to its size, awkwardness, and importance to safety, the windshield gets all of the attention when it comes to accurate placement.

To properly set a glass into an opening, it is imperative to have access to all sides of the glass part and the opening. Tucking the glass under the cowl panel is not an acceptable procedure.  The technician cannot see the lower bead contact the adhesive and cannot correct a displaced bead after setting it because of the cowl panel’s presence.

There are many procedures and tools available to aid in setting the glass. Some may take extra effort, more practice, or additional cost than others, but the choice is that of the technician.

Once the glass is set in the opening and on the adhesive, the next step is to “deck” it out and make the seal. This is accomplished by the firm but gentle depression of the glass into the opening. How far into the opening the glass is depressed is important, if it’s too far and the glass could be susceptible to stress cracks. On the other hand, if it’s too little, and the glass will not perform its safety role in a crash.

The ideal positioning in the opening is dependent on the style of the vehicle. In a vehicle equipped with exterior mouldings the outside glass surface should be tight against the underside of the exterior mouldings and spaced high enough from the interior mouldings to prevent unpleasant noises.

If the glass has an exposed-edge style of mounting, then the glass positioning should be slightly lower than flush with the roofline. If it’s flush with the roofline, the glass and body can cause a noise called the “flute” effect. The air blows over the gap between the glass edge and the wall of the pinchweld causing a whistle or air rush noise. If the glass is too high, then the windshield will not support the roof to FMVSS 216a required for safety. If the glass is decked too low and the glass loses its freedom of movement and can cause stress fractures.

Setting the glass is vital to the success of the installation and must be accomplished flawlessly every time. Do not take shortcuts with this step.

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.

The word “Refracturing,” would be defined as re-breaking of a previously repaired chip. However, I use the term in a different way. I define it as a process in which a chip is made larger to enable you to fix it faster and better. To be more specific, we created a bullseye break at the pit to create a basin for the resin to flow easier to the other legs of the break.

Refracturing is done for a few reasons. For one, it makes a repair faster by evenly distributing the resin and because it doesn’t have to be pressured through the tight recesses of a crack or star type break. The other reason is quality of repair; a half-moon break will repair easier if you cause the half-moon to become a bullseye. To do that, you cause the half-moon to finish breaking and become a bullseye break.

             

Before refracturing                After refracturing

How do you complete a refracturing? First you need practice before doing it on a customer’s vehicle; take an old windshield and practice on surface divets on the glass. It takes a darning needle, larger sewing needle or sharp pick and a weighted tool. I use the handle of a screwdriver or other hand tools.  Next, place the pointed tip of the pick or needle into the pit of the break and tap the dull end with the weighted tool until a small bullseye is created under the pit. It may take several tries to get the hang of it but practice makes perfect. Now, fill in the break normally; the bullseye portion you created will disappear and the far reaches of the break will repair faster.

 

 

 

 

 

If you wish to make a bullseye break from a half moon, the first thing you must do is check the existing break and make sure that the ends of the moon are pointing inward and not outward. If they are pointing outward, the break will run against the pit instead of finishing the bullseye when the refracturing process is applied. However, if the tips of the half moon are pointing inward, the break will finish the circular bullseye due to the natural circular grain of the glass making a chip easy to repair.

Refracturing is a technique that works, give it a try, you won’t be sorry.