Windshield Repair Tips
Frequently Asked Questions From Windshield Repair Technicians
Q: What is considered the acute area of a windshield and is it illegal to do a windshield repair in that area?
A: According to the National Windshield Repair Association's recommended practices committee, the acute area of a windshield is approximately 8.5 inches high by 11 inches wide directly in front of the driver and beginning just above the center of the steering wheel. It is not illegal to perform a windshield repair in the driver's direct line of vision, however some insurance companies and state inspection stations do not approve of windshield repairs in that area.
Q: Why do drill bits sometimes break just as they penetrate the first layer of glass?
A: The most common problem is generally that the technician has not rotated the drill in a circular motion during the windshield repair drilling process. Using this procedure will not only eliminate the bit breaking problem but will also shape the hole in such a way that air bubbles will be much easier to remove from the drill hole. Another solution is to drill halfway through the outer layer of glass, then insert a thin probe, such as the DKI 77-7D double ended scribe, into the break and tap lightly with a suction cup removal tool or similar object. A very small bullseye will be created at the bottom of the drill hole and will not damage the laminate . This procedure is also very effective for stopping long cracks.
Q: When I finish a windshield repair it looks great but later it seems to reappear. What is happening?
A1: There are two main reasons for this problem, the most common of which is overheating. While warming the glass to 80 or 90 degrees can be very beneficial, heating the glass past that point causes the glass to expand, pushing the windshield repair resin out of the crack. It looks repaired initially, but in fact has no resin in the cracks, thus no bonding strength. When the glass is cooled it contracts and the cracks reappear. To test this theory, heat a rock chip on a piece of scrap glass without putting any windshield repair resin in it. Small chips and cracks will often disappear. Now cool the glass and see what happens.
A2: The second most common reason for this problem is putting too much pressure on the windshield when affixing the windshield repair bridge and injector to the windshield. If the windshield repair injector is over-tightened, the glass will flex in and the cracks will close just as when overheated. To eliminate this problem, once the injector seal has made contact with the glass, rotate the windshield repair injector one more complete turn, then make your final leveling adjustments with the rear adjusting screws.
Q: Why won't the windshield repair resin cure?
A1: There are many possibilities to consider but the most common one will surprise you. Many types of sandwich wrap, cellophane, etc., actually block ultra violet light. Be sure to use Delta Kits brand curing tape, tabs or strips on your windshield repair for best results.
A2: If you are using a light to cure the windshield repair resin, be sure the batteries are fresh. Don't laugh, 90% of the lights sent back to Delta Kits for repair just need batteries. If the batteries are good, try a new bulb. If these solutions fail to remedy the problem, try curing the windshield repair resin in the sunlight. If it is determined that the problem is in the circuitry of the light itself, call Delta Kits for a return authorization.
A3: Contaminated windshield repair resin is the least likely of all curing problems but it has been known to happen. Never return used resin to the resin bottle as it can contain a variety of contaminates from the glass surface.
Q: Why is the windshield repair resin taking so long to cure?
A1: Always use Premium Pit Resin prior to curing the windshield repair . It will cure faster and leave a flat glasslike finish to the windshield repair . Failure to use Premium Pit Resin can result in longer curing times and it may be necessary to use several applications of thin resin to achieve the same results.
A2: Refer to the last Q/A for possible solutions concerning curing film, lights, etc.
A3: Some UV lights cure faster than others. As a rule of thumb, 120V/240V lights cure the fastest, followed by 12V lights, with battery operated lights bringing up the rear. Generally speaking, the bigger the battery size, the faster it will cure. Customers often prefer battery operated lights due to the versatility and low cost but pay the price in performance.
Q: Why does the pit resin come off the windshield when I pull off the curing film?
A: Usually this problem is a result of a prior application of wax, Rain-X or similar glass treatment. Use Premium Pit Polish, Pumice, Cerium Oxide or EZ Kleen to remove the treatment prior to repairing . Cheap brands of pit resin have also been known to have this problem even when glass treatments are not present.
Q: Why can I still feel the pit after I have finished the windshield repair?
A: Either no pit resin was used or you forgot to leave a hump under the curing film. Many repair technicians push down on the curing film to flatten it out before curing. By allowing the film to lay gently over the pit resin, it will leave a hump that once cured, is easily scraped flush with the glass.
Q: How do I get the air bubbles out of a drill hole?
A: When you are finished filling the break, put a drop of pit resin on the hole and put your curing film partially over it. While holding the film back, use a needle or straight pin to work the bubble to the top of the resin. When you lay the remainder of the film over the hole, the bubble will be pushed out to the edge of the film.
Q: How can I keep the windshield repair resin from curing before the cracks are filled when doing repairs outdoors in the sunlight?
A: The bridge assembly and area being repaired should be covered with a UV sunshield until the repair is ready to be cured.
Q: Will the sun cure the windshield repair resin before I am finished with the repair?
A: Sunlight will cause the windshield repair resin to cure prematurely if the repair is exposed to it before the repair is finished. To avoid this situation, cover the bridge assembly and the repair with the Delta Kits UV Shield. It has suction cups on all four corners so it can be attached to the glass and will not blow off during your windshield repair. This is a worthwhile investment if you plan to do windshield repairs outside.
Q: How hot can I heat the glass?
A: There is a lot of speculation on how hot is too hot but as a rule of thumb "pun intended," if it is too hot to hold your thumb against, you should let it cool before proceeding with your windshield repair. Some techs feel that if the glass is above room temperature it will expand and the cracks will close. This may be true if you only heat the very spot that you plan to work on, but if you evenly heat the area for several inches around the repair, you are able to benefit from the extra heat without closing the cracks. In fact for the most part, you will find that your best windshield repairs are done in hot weather when the glass is almost too hot to touch. Again the most important factor is that you keep that windshield repair resin and glass temperature as consistent as possible.
Q: How do I know when to drill a break?
A: 98% of all windshield repairs do not need to be drilled. Typically if there is glass missing from the center of the damaged area, there will be sufficient space to inject the windshield repair resin into the break. You can push lightly on the center of the break from the outside using a carbide scribe and watch for movement in either the cracks or the air space. If movement exists, you probably do not need to drill. If movement does not exist and there is little or no glass missing from the center of the break, it may be beneficial to drill. If you find that you are unable to get windshield repair resin into an un-drilled break, you can loosen the wing nut in the center of the bridge assembly, swivel the injector away from the break and drill it. Then swivel the injector back over the break, tighten the center wing nut and resume the injection process. Usually the injector will hold enough windshield repair resin in the seal to finish the job, however in some instances you may have to add a few more drops of resin. Some repair technicians drill all repairs. While this will often speed up the windshield repair process, there will be a loss in cosmetic appearance whenever a repair has to be drilled therefore we do not recommend drilling unless necessary. One possible exception to this rule is when doing truck or bus fleets. Often times, fleet managers are not as concerned about the appearance as they are about the strength of the repair and the lack of downtime to the vehicle. In this instance we recommend that you discuss the process with the fleet manager in order to fulfill his/her expectations.
Q: How do I repair a vertical windshield such as those found in a bus or motor home?
A: When attaching the bridge to the windshield, be sure it is pointing toward the top of the glass and the adjusting screws are lower on the windshield than the injector. Screw the injector body down until it just comes in contact with the glass. Do not give it the extra turn that you normally would. Level the bridge with the adjusting screws as usual but then continue tightening them so that the base is tipped slightly forward so the resin will not run out of the injector. When you insert resin into the injector, use a syringe to insure that resin gets into the seal without filling the threads of the injector body . You may need to use slightly more resin when performing vertical repairs.
Q: Can heated windshields be repaired?
A: There are three types of heated windshields that we are aware of. One type heats only the wiper area by using grid lines on the inside layer of glass. This type of windshield can be repaired if with no adverse affect. If a grid line is broken by the damage in the glass it will no longer function properly even after you have completed the repair however one broken grid line should not affect the operation of the others. Another type of windshield is heated by tiny wires inside the layer of PVB between the two layers of glass. This type of windshield can be repaired successfully however if the PVB is damaged, which normally it is not, the area of the damage will not be heated. The third type has a coating on the inside of the outer layer of glass. The windshield manufacturers have recommended that this type not be repaired, as it is possible that it could cause damage to the electrical system. Although we have witnessed several successful repairs on this type of windshield, we always suggest following the manufacturers recommendations.
Q: How do I repair a break on the inside of a windshield?
A: Before you attach the bridge assembly to the glass, you must screw the plunger into the injector body and set the plunger to the pressure (down) position. Place the tip of the injector against a hard, flat surface and apply pressure to the top knob of the plunger until the tip of the plunger moves about half way through the seal. To make this task easier, lubricate the inside of the seal with a drop of resin before you start. With the plunger in place, turn the bridge assembly over and fill the remaining space in the seal with resin. Now pull back slightly on the plunger to create a vacuum that will help hold the resin in place until the bridge is in place. Be sure not to pull the plunger to far or the resin will run out the other side of the injector. Attach the bridge assembly to the glass and position the inject or over the break and proceed as usual . When you apply the vacuum cycle, do not pull back the plunger and lock it in the vacuum position or the resin will run out the backside of the injector. Instead, turn the plunger counter clockwise a couple of turns, always being careful not to allow it to back completely out of the seal. Alternate between the pressure and vacuum cycles by turning the plunger clockwise for pressure and counterclockwise for vacuum. It may take a bit longer and require more cycles to complete the repair so leave plenty of time. Windshield repairs on the inside of the windshield are uncommon and require some practice in order to be successful. They can also be messy of done in correctly so always protect the interior of the vehicle case of resin leakage.
Q: Should I cure the windshield repair under pressure?
A. This is a repair technique used by many windshield repair technicians when they fail to properly fill the repair. They believe that when the injector is removed the break will suck in air from the surface. If this is happening, the tech is probably applying too much pressure to the glass, flexing it inward and closing the cracks. When the pressure is released the glass returns to its original position and the break pulls in air. When done properly the break will be full of resin and therefore will not pull in air. However as every good technician will tell you, there are exceptions to every rule, so when all else fails you can try curing under pressure. But whenever possible it is best to cure the repair when the glass is in it¹s original state to eliminate any undue stress.
Q: Do I need a different viscosity of resin for different climate or type of break?
A: No. Delta Kits resins are formulated for use in all climates and are suitable for all types of breaks. Resin viscosity is a matter of preference however a low viscosity (thin) resin works best for all types of repairs. So why do other companies sell so many different viscosities of resin? More money for them!
Q: Do I need a tinted resin for different tints of a windshield?
A: No. The tint in a windshield is very subtle and a good clear resin will blend in as well as or better than a tinted resin. There are more than 25 variations of tinted glass used for windshields and it would be nearly impossible to match each one. You will often see a dark shaded band at the top of the windshield. The color of the shade band actually comes from color that is added to the PVB inner layer. Windshield repair is a process that repairs the glass, not the PVB layer, so using a tinted resin will not be effective in the shade band either. So why do other companies sell tinted resin? More money for them!
Q: Is there a difference in windshield repair resins?
A: Absolutely. We have tested resins that when cured, do not even stick to the glass. In fact, we believe this is one of the main reasons some companies do not sell pit resin. A poor quality resin will shrink up quickly and the ³pit² will fall out over a period of time if the bonding strength is substandard. A high quality resin will actually etch the glass just enough to create the optimum bonding surface, will not shrink, discolor or fall out of the pit area. The etching is microscopic and cannot be seen by the naked eye so you need not be concerned about any cosmetic damage to the glass.
Q: Why do my repairs sometimes get a flower shaped watery look to them?
A: Excessive heat and/or pressure may cause the glass to separate from the laminate, allowing the resin to flow out past border of the original damaged area. This problem is most common in very hot climates and in breaks such as bulls-eyes and large combination breaks, but may also occur at the end of a crack. Sometimes called the "Daisy Effect," it is not a structural problem but can be visually unappealing . Try cooling the glass prior to repair and using less pressure in the summer time. Laying a towel over the glass or using a Delta Kits Sun Screen for a few minutes prior to attempting are pair will help cool the glass when shade is not available. I t is not usually necessary to heat the glass if the air temperature is above 80 degrees Fahrenheit.
Q: Should I heat a break before or during the repair process?
A: Starting with a warm windshield and warm resin seems to make thing s work a bit smoother but it is really a matter of preference. Heating after the beginning the re pair does offer some advantages. You save time by heating during the injection process and with resin already in the break, you are heating it and the glass at the same time so the temperatures stay consistent. You can heat are pair in either the pressure or the vacuum cycle but use caution when heating in the pressure cycle so as not to create a "daisy effect." See the Q&A above for a description of the daisy effect. However heating under pressure can be a very effective way to get resin into stubborn cracks.
Q: Some repair system manufacturers say that you need to vacuum all the air out of a break before injecting the resin, is this true?
A: Of course not. Think of an empty pop can. It is full of air but you do not need to suck the air out of it before you fill it right? In fact if you did, the pop can would collapse. The same is true for a windshield repair. As the resin flows into the break the air is forced to the outside edge. When the vacuum cycle is initiated, the air is pulled up through the resin and into the injector and when the injector plunger is locked in the top position the air is released through the top of the injector. As the air is removed it is replaced by resin.
Q: What is the best way to clean my windshield repair equipment?
A: Use an air compressor or can of compressed air to blow excess resin from the inside of the injector body and the outside threads of the injector plunger. If you do not have access to compressed air, simply wipe off the individual pieces of the injector and store them in their respective locations inside your Delta Kits tool box . Do not leave the two pieces of the injector screwed together during storage. Denatured alcohol can be used for cleaning if you prefer however it is not necessary if you clean your equipment after each windshield repair.
Q: Do wax and soap from car washes affect the quality of a windshield repair?
A: Yes. Some soaps and waxes contain agents that help reduce water spots. Some of these agents react with the resin causing it to "rise" out of the break after it is cured. Generally this problem does not show up for several hours or even several days and it is virtually impossible to detect before starting the repair. Use compressed air to blow out any soap or wax residue in the break before you start to avoid this problem. Most office supply stores sell small cans of compressed air or gas with alcohol that work very well to help clean and dry the break. Using an air compressor is not recommended unless fitted with filters for moisture and oil. Regulate airflow to no more than 20 pounds if using an air compressor.
Q: Can the inside layer of glass be damaged and if so how do you repair it.
A: Occasionally the layer of glass on the inside of the laminate may be damaged and can be difficult to recognize. Typically the cracks will appear thinner and not as dark as the cracks in the outer layer of glass. You should always use your steel scribe to check which side of the glass the cracks are on by moving the point lightly across the crack. If you can feel it, you know the crack is on that side. If you cannot feel the crack on the inside layer but you are still having trouble filling the crack, it may be that the inner layer of glass is damaged but the cracks do not go all the way through. In these rare instances, the repair may not fill properly. Some technicians will drill all the way through the laminate or drill from the inside of the vehicle in order to complete the repair but those techniques are not advised.
Q: Can solar glass be repaired?
A: There are two types of solar glass. 1: Batch solar glass has the solar protection material added to the liquid glass during the production process and may be repaired. Most vehicles utilizing solar glass use batch solar glass. 2: Solar coated glass features a transparent metal/metal oxide coating on the inside surface of the outer glass. Solar coated glass is produced by PPG and is identified with the name “Sungate”. The manufacturer does not recommend repairing solar coated glass because when air comes into contact with the solar coating, the glass may start to delaminate, creating a weak spot and causing the glass to become unsafe. Testing by Delta Kits has proven that repairing solar coated glass increases the strength of the damaged area significantly but we always suggest following the manufacturer’s recommendations. Repairs to severely damaged solar controlled windshields may leave a white ring around the outside of the repair. If drilling is necessary, do not drill all the way through the first layer of glass as the solar coating may be further damaged.
Q: Can a rain sensor windshield be repaired?
A: The glass and laminate of a rain sensor windshield are exactly the same as any other windshield. Rain sensors are small and are attached to the inside of the glass, so the windshield itself may be repaired without any adverse affect. However, the amount of light reflected through the glass controls the sensor, so if a rock hits at the very point where the rain sensor is attached, it could cause the rain sensor to malfunction. Even after the rock chip is repaired it is likely that the light refraction in the repaired area will be different than the undamaged glass. Some vehicles such as those manufactured by General Motors, have rain sensors that may be moved to an undamaged area if necessary. Other vehicles utilize a different design that necessitates the location of the rain sensor to be in a small opening in the paint band. A rock chip in this area will often require the replacement of the windshield to restore the functionality of the rain sensor. Mercedes and BMW are among those that use this design. Tests have not shown that performing a repair in the rain sensor area will have a negative effect on the operation of a properly working rain sensor, nor have tests shown that repairs in this area will improve the operation of a dysfunctional rain sensor.
Q: Why can’t I get rock chips and cracks to fill properly when I am working in the sunshine?
A: If you are not using a ultraviolet shield the resin is probably curing prematurely and therefore blocks the path of the resin. It is very important that you block the sun’s UV rays until you are ready to cure the repair.
Problem: Injector plunger is stuck in the upright position or stuck in the injector barrel.
Solution: Thoroughly clean the injector after every repair by blowing off the outside and blowing out the inside with compressed air or rinsing both parts in denatured alcohol. Store parts separately. Store the plunger in the down position so the spring is fully extended. Never turn the bridge or injector upside down when it has resin in it. If this happens unintentionally, clean with denatured alcohol immediately.
