If you have been a Delta Kits customer for very long, you probably know that we recommend drilling only as a last resort. For the very best cosmetic results, only drill when you are unable to get the resin to flow into the break any other way. That said, we have plenty of customers that do drill, so here are a couple of things to think about.
First, your drill hole itself is going to be quite visible, so drill as shallow as possible (or not at all). Second, remember that when you drill, resin will often drain from that drill hole and leave a small, shiny, or black air bubble. Pit resin is just too thick to flow down into the bottom of your drill hole, so that air is just trapped there as the pit resin is applied. Air bubbles can also be incorporated into the drill hole from trapped air in the tip of the pit resin bottle or from applying a curing tab improperly.
Storing your pit resin bottle upside down for at least five minutes prior to starting the repair will eliminate any chance of air bubbles in the pit resin itself. Make a habit of doing this for every repair, and keep the bottle upside down as you remove the cap and apply the resin. If the bottle is turned upright at any time air bubbles may be trapped in the tip and squeezed out with the resin.
Don’t drill unless you can’t get the resin in any other way. If you have to drill, make sure you never go deeper than 2/3 through the outer lite and try to angle your drill hole toward the bottom of the windshield so the resin is less apt to flow out. Place the lower edge of a curing tab below the drill hole being careful to hold the tab away from the hole until the pit resin is applied. Apply a drop of pit resin at the point where the tab meets the glass, and allow the tab to slowly cover the hole. This procedure uses the pit resin to push any thin resin that has seeped from the hole back into the hole before the pit resin covers it, minimizing the chance of trapping an air bubble.
Following these simple steps will greatly minimize the chance of trapping air in a drill hole, but if you have followed these directions and still have a small air bubble under your pit resin, lift the top edge of the tab just enough to access the drill hole, apply another drop of pit resin directly on top of the drill hole, and use a sewing needle to work the bubble out of the hole, then allow the tab to gently fold back over the hole as the needle is slowly removed. The key here is to use the curing tab to create a small pool of pit resin on top of the hole so when the bubble is removed it is immediately replaced by pit resin. Voila, no more bubble in the drill hole.
The above method is the Delta Kits preferred technique and works well in almost every instance, but another option that some technicians prefer goes like this. Fill a blunt needle syringe with a few drops of thin resin and place the tip of the needle in the bottom of the drill hole. Slowly begin forcing resin into the bottom of the hole while slowly raising the needle up out of the hole. Doing so washes out any air bubbles previously trapped in the drill hold. Keep in mind you will still need to have your curing tab in place with a drop of pit resin ready to fold over the hole as soon as the needle is removed.
The first time you try either of these methods it may seem like you need three hands, but with a little practice it will become second nature and eliminate the air bubble in the drill hole problem.