DIY Network

Repairing a Chipped Windshield A chip may seem minor, but it can grow into a sizeable crack if not properly repaired. From "Car Care & Repair" episode CCR-122

A chip or ding in a windshield may seem like a minor thing, but left alone, that tiny chip can grow into a sizeable crack. A cracked windshield can obstruct the driver's vision, and is therefore a safety hazard. In fact, in most places driving with a cracked windshield is illegal, and a traffic citation can be issued for the offense.

Fortunately, a small windshield chip can actually be repaired is such a way that the repair is barely visible. And though many people are unaware of it, most auto insurance policies cover minor windshield repair and will reimburse 100 percent of the repair cost.

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	Figure A
	Figure B
	Figure C
	Figure D
	Figure E
	Figure F
	Figure G
	Figure H
	Figure I
	Figure J

Auto glass specialist Terry Ranta demonstrates how the repair is made. Though it's not a major procedure, this is a job does require some specialized equipment and expertise, so it's best left to professionals at an auto-glass shop.

The type of damage repaired in our demonstration is known as a combination chip (figure A), meaning that it includes a center chip surrounded by a series of small cracks spreading out radially like spider legs. This type of chip is likely to spread into a larger crack if left unrepaired. The means by which a small crack grows into a larger one is the result of tiny amounts of moisture getting into the crack. Since windshields are actually made of two layers of glass with a safety-laminate layer in between, moisture forms beneath the outer layer of glass. When the moisture expands because of fluctuations in temperature, it can cause the crack to enlarge and spread longitudinally. (Tiny chips that don't have the radial cracks are less likely to spread, and generally don't need to be repaired unless they are hindering driver vision.)

The repair consists of injecting a resin material into the center of the chipped area. Pressure is then applied, using a vacuum device, so that the resin spreads into the tiny cracks. The first step involves using a high-speed drill and specialized bit to drill out the center of the damaged portion (figure B), much as a dentist drills out a cavity in a tooth. The drill is used first on a low setting to remove surface debris, then on a high-speed setting to actually drill a tiny hole in the center of the chip.

Once the center has been sufficiently drilled out and the powdered-glass residue removed, a specialized injector is positioned so that it can deliver a small amount of repair sealant directly into the center of the crack (figure C). The injector housing is held perfectly stationary by means of a heavy-duty suction cup that attaches to the glass surface (figure D).

Resin is placed in the injector, and a vacuum pump is attached (figure E). Injector is first set to create a vacuum to remove the air from inside the crack. After all the air has been removed, the setting on the injector is changed so that it applies pressure (figure F).

With a pressure reading of about 25 psi, the resin begins filling the cracks (figure G).

After a waiting period of about 5 minutes, the injector is removed. A small piece of cellophane tape is placed over the crack to hold the resin in place while an ultraviolet light is applied to dry the resin (figure H).

When the resin is completely dried, the light source is removed and any residue is cleaned away using a razor blade (figure I).

Finally the area is cleaned with ordinary glass cleaner (figure J). Once finished, the repair is practically imperceptible.

RESOURCES :

Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896

Some vehicles provided by Ted Russell Ford

Ted Russell Ford
8551 Kingston Pike
Knoxville, TN 37919
Phone: 865-693-7611
Web site: www.tedrussell.com

Special thanks to Classic Auto Glass

Classic Auto Glass
La Follette, TN