Windshield Repair Tips

All repair technicians do not agree on the primary purpose of windshield repair. Some think the primary purpose of windshield repair should be cosmetic improvement. Others think structural restoration should be primary purpose. What difference does it make? To me, it makes a lot of difference. If cosmetics are to be the main purpose of repair, forget it! The only way you "make the damage disappear" is by replacing the windshield. Since repair seeks to avoid the need to replace the windshield, the primary purpose of repair must be structural restoration, and that means filling the entire airspace in the damage with repair fluid. For me, it does not make sense to leave air in the tips of a star break (or anywhere in the damage) simply because the repair will not look as good if we have to make another hole or two in the glass to access such air pockets. It is imperative that getting the entire airspace in a damage filled take priority over cosmetic improvement when we are doing windshield repairs. It is equally imperative that we educate our customers concerning this priority. Cosmetic improvement must always be secondary to structural restoration when doing repairs.


HOW TO FILL STAR BREAKS

There are three basic ways to coax resin out to the tips of the legs of stars. The first is vacuum pressure. The second is through the application of heat to the inside of the windshield, and the third is by using the flex method.

1. Almost everybody is familiar in one way or another with the vacuum pressure method. It consists mainly of creating a seal between the injector and the windshield, and then through various processes creating vacuum to remove air while applying pressure on the resin to take the place of the existing air When the star's legs refuse to fill completely, the process is repeated one or more times. Pros: Simple with most systems. Very little chance of star's legs spreading. Cons: Very time consuming and has very little success on damages larger than a nickel or a quarter

2. The application of heat to the inside of the windshield is another process that many of you are familiar with and often use in conjunction with the vacuum pressure method. Some technicians advocate using heat during the vacuum segment and some advocate using it during the pressure segment. Let's examine what happens in a leg during the introduction of heat so you can decide which to use and when. As soon as you apply heat to a start damaged windshield, two things begin to happen:

A. The viscosity of the resin begins to drop making it thinner so it flows more easily.

B. As the temperature of the glass increases, the glass begins to expand and the leg of the crack begins to close leaving less space between the walls of the crack.

Now, if you apply heat during the vacuum segment of the process, theoretically the expanding glass could close the crack and force air out. However the danger here is that when the glass expands too much, it closes to the point that the refraction disappears, leading the technician to the assumption that it has resin in it, and he begins the curing process only to find that when it is cured and the glass cools, there are few tips that have refraction and are not bonded, and the star reappears.

Now, if we apply heat during the pressure segment, the glass warms, heating the resins and causing it to flow more easily, helping the technician repair the damaged area more quickly. However, if you are to get positive results from the process, you must give great attention to the temperature of the windshield as you are adding heat.

Too much heat will again cause the leg to close down, giving it the appearance of being full without any resin in the tips. Also, at temperatures slightly over 115 degrees, you can begin to damage the qualities of your resins.

Pros: On cool windshields the average stars can be repaired more quickly with little effort IF close attention is paid to the temperature applied to the glass. This takes practice and close concentration!

Cons: Often legs close due to expanding glass leading to premature curing and incomplete fills. Also, the process is nearly useless on warm and hot windshields. If there is a drastic temperature change you can cause the cracks to grow if heated locally. And finally, the process has only limited success on stars larger than a quarter

3. Some of you may not be familiar with the flexing method, but give me your attention and we will examine this one closely. Before beginning any repair, it would be wise to make sure the windshield is at the best temperature. If it is too hot, cool it down; it it is too cold, warm it up. Next, make sure your injector and resins are at room temperature. This helps ease many complications before they arise.

With everything at standard temperature and pressure (STP), prepare your tools, resins, windshield, damage, etc., as usual. When you affix your tools (holding structure) to the windshield, be careful to have enough bridge pressure to create a seal with the 0-ring and no more. Excess pressure only increases the chance of damage spreading and reduces the effectiveness of the flexing method. After you have completed your initial standard vacuum-pressure, allow the resin to flow on its own for several minutes.

If after several minutes, some of the legs have not filled, try flexing them one at a time. Apply a little pressure directly onto the leg in question as close to the injector as is reasonable.

First, start with very light pressure and watch what happens to the unfilled portion of the crack as you gradually apply more pressure. What happens is the crack begins to open up at the base of the crack next to the laminate. Each crack will require a slightly different amount of pressure. As you apply pressure it will seem that the crack spreads towards the injector As the crack opens, areas that are full will begin to lose contact with resin. This is evidence the crack is opening. As soon as you see it opening, hold the pressure constant. At first hold it for about twenty seconds and watch the resin flow out to the tip. With most cracks one exercise will be enough.

DRILLING

When starting to repair a stone break, one of the first things a professional repair technician does is determine whether or not this break will require drilling. Most professional technicians can tell at a glance whether it will be needed. If there is a bull's-eye (dark circles under the impact point), it will normally NOT require drilling. If, however you question whether you need to drill or not there are a few steps you can take to determine this.

The most common step to determine drilling is to take one drop of thin, stone damage resin and place it on the impact point. If you see resin seep into the break, the impact point will not require drilling. If no resin flows in, drilling is required. Drill into the impact point if there is no bull's-eye. About 3-5 seconds is enough. Then using a size 14 sewing machine needle place tip in hole and tap lightly with a razor blade holder (the one shaped like a piece of gum). This will make a miniature bull's-eye, which will allow easy access to the crack or cracks, (this technique has been used for more than a decade.) The rule of thumb in windshield repair is if it didn't fill, drill. That means any part of the break not filled with resin should be drilled and filled or your repair is worthless. When not drilling into an impact point, drill about half way through the outer layer and then tap. Do Not Drill into the lamination that would leave a permanent blemish.