All about Auto Glass Repair:

There are two types of Auto Glass in use today… laminated and tempered. Both of these types are considered safety glass, but each has a different job to do

LAMINATED AUTO GLASS keeps the occupants inside the vehicle in case of a collision. Laminated auto glass is used primarily in windshields, but may also be used in other auto glass parts. Laminated glass consists of two sheets of float glass with a sheet of plastic (poly vinyl butyric, or PVB) sandwiched in between. According to federal standards, windshields must have PVB thickness of not less than .030 inch.

Although all PVB in laminated glass must meet federal standards for thickness, the actual glass thickness may vary. Early automotive vehicles used very thick auto glass until the fuel shortage occurred in the early 1970s. After that, glass had to be reduced in thickness to lighten the total weight of a vehicle in order to increase fuel efficiency. Since then, windshields have become thinner and thinner.

The PVB gives laminated glass its safety label. The PVB’s .030 inch thickness provides the windshield with the strength to hold the occupants inside a vehicle during a frontal impact. In other words, the windshield must be able to absorb the energy applied upon it by the occupants being thrown against it. The windshield can then cushion the impact and help avoid serious injury. The PVB holds the broken glass and forms a barrier to prevent the occupants from being thrown through the windshield. If the two glass layers break, then glass shards adhere to the PVB rather than showering the occupants with potentially life-threatening pieces of jagged glass.

TEMPERED AUTO GLASS adds strength to the door auto glass and back/rear windows. Its breaking pattern reduces serious injuries.

Unlike laminated auto glass that consists of two sheets of glass, tempered glass is a single pane of glass that has gone through a tempering or heating process with rapid cooling that strengthens the glass. Tempered glass is five to ten times stronger than normal flat glass, and it can withstand drastic temperature changes. Tempered glass, with its strength and flexibility, has many auto uses, but is only used in side and rear auto glass applications in the U.S.

The tempering process uses an oven that reheats the glass to temperatures that bring the glass to a nearly liquid state. The glass is then removed from the oven and exposed immediately to cool air. This cools the outside surface of the glass first and then gradually cools the core of the glass, causing a state of compression.

This compression is what gives tempered glass its strength. To fracture tempered glass, you must overcome this state of compression. When this occurs, the glass breaks in a unique breakage pattern called “dicing”. The tempered glass pieces are very small, cube-shaped and have relatively dull edges. In a collision, the dicing phenomenon greatly reduces the possibility of serious injury caused by broken glass.

Both types of auto glass play very important roles in the overall safety of a vehicle’s passengers.

Both laminated and tempered glass may be coated with a chemical film that provides additional features, such as privacy or a mirror effect. This solar coating helps to reduce the sun’s ultraviolet rays entering a vehicle and moderates the temperature in the passengers compartment. This solar coating also helps reduce the strain on a vehicle’s air conditioning system as well as the drag on the engine, which, in turn, limits the risk of overheating and increases fuel efficiency.

Automobile Body Styles

Body styles are the various designs manufactures use, such as coupes, sedans, hatchbacks, notchbacks, and station wagons. In the past, almost every vehicle model was available as a two-door coupe, four-door sedan or two- or four-door station wagon. Now, however, auto manufactures sell special models for different body styles. The body styles currently produced are

Auto Glass –types of auto

• Sedan (2- and 4-door)
• Station wagon (5-door)
• Convertible
• Hardtop (2- and 4-door)
• Hatchback (lift back)
• Limousine
• Coupe (2-door)
• Notchback

Auto Glass Van/Truck/Utility

• Mini Van
• Utility (2- and 4-door)
• Crew cab (4-door)
• Cab-over-engine (C.O.E/tilt cab)
• Full size van
• Sport utility (2-door)
• Extended cab (2-door)
• Extended van
• Pickup (2-door)
• Conventional cab

AUTO GLASS COLORS

Although it would appear that auto glass is clear, it really is not. Clear auto glass is almost obsolete. There are over 25 auto glass color options. Color is added when the raw materials of sand, soda ash and limestone are melted into molten glass. The main colors or tints that can be added are: Black, Blue, Bronze, Gray, Green, Rouge, and Clear.

Shaded glass is laminated where a dark color has been added to the top section of the PVB layer that gradually becomes lighter as the tint travels down the glass. The dark color helps to improve the driver’s visibility by reducing glare when the driving in sunlight.

The main sunshade color options are: Blue, Bronze, Gray, Green.

When the various glass tint options and sunshade options are combined, there is a large selection from which to choose. There is one condition, however: tempered glass cannot be sunshaded because it takes two pieces of glass and an inner layer to create a sunshaded piece of glass.

Every auto glass part, whether from the original equipment manufacturer (OEM) or a replacement, bears identification coding in the form of a monogram. The auto glass part monogram is commonly known as a “bug” or “sandblast.”

The monogram contains these items of information

• Manufacturer’s trademark (brand/type)
• Manufacturer’s logo
• Plant code (location where part was manufactured)
• Type of glass (laminated or tempered)
• Month and year of manufacture
• Model number
• Department of Transportation (DOT) certification number
• Glass code

Auto Glass Repair

Step One: Inspecting the damage

Before undertaking a windshield repair job, you should inspect the damage to determine if windshield repair is the correct procedure. When you inspect the damage, follow the guidelines below:

A. Is the damage less than a quarter?
B. What is the pit size?
C.What type of damage is it?
D. Is the damage contaminated?
E.Is it PVB or inner-lite damage?
F. Is it a heated, anti-lacerative, or solar windshield?

After you have inspected the damage and have determined that repairing the windshield is the correct procedure, review your findings with your customer, You do that by:

A. Explaining the damaged area
B. describing the repair process
C. Gaining customer understanding of the process and its outcome

It is especially important to let the customer know that while the repair will restore the structural integrity of the windshield, prevent the break from spreading, and improve the appearance of the windshield, a repair will not make the damage disappear completely. It is also important to let the customer know that the finished appearance of the windshield will vary according to the amount of damage initially as well as with the age of the damage.

Note: If the damage is located on an anti-lacerative windshield, do not use heat or tools on the inside surface. The plastic layer could be damaged.

Windshield Repair

It is not always necessary to replace damaged windshields. Sometimes a routine repair will prevent small breaks from spreading. Often, such minor damage is caused by stones. Left untreated, the break will spread, but with early intervention you can spare the customer the cost of a new windshield.

When do you need Auto Glass Windshield Repair?

A windshield consists of two layers of glass and a layer of plastic in between. The middle layer is polyvinyl or PVB. When an object strikes the windshield, it creates a small pit at the impact point. Underneath, a cone breaks free from the surrounding glass. When this happens, it is called the separation. Although some damage may be repaired, when the laminate and the inboard part are damaged or if delaminating has occurred, the windshield must be replaced.

Windshield replacement should also be done if the beak occurs in the driver’s line of vision. At night, oncoming headlights may post a hazard under such conditions.

It is not possible to guarantee that a repaired windshield will pass state inspection. There are no federal laws, but there are some state laws that regulate windshield repair. Whether to repair or replace a windshield is a subjective decision by each inspector.

Note: Check your state’s regulations

In making a recommendation to the customer, consider the extent of the damage and its location on the windshield. It is better to be safe than sorry.

As a guideline, breaks larger than a quarter should not be repaired. The integrity of the repaired glass may not be as strong as the original windshield. Larger repairs also are more difficult to hide and take longer to repair, costing the customer more in time and labor.

Insurance companies and individual auto glass replacement/repair shops sometimes differ in what they consider the driver’s line of vision area of the windshield. Some consider the area swept by the driver’s wiper blade to the critical or wiper area. Others consider the area directly in front of the driver’s eyes, which is called the acute area. The acute area measures 5 1/2 by 8 1/2 inches. Still others define this area as the most of the driver’s side vision area except a 4-inch section on the top and sides, and a 5-inch section on the bottom. This is called the primary vision area.

Most auto glass replacement shops and insurance companies in the United States use the acute area as the standard for the driver’s critical vision area. This, too, is not black and white because it depends on the height of the person behind the wheel.

1. Place the inspection mirror on the inside of the windshield
2. Inspect and flex the break, using the inspection light. Use your probe to flex the area on and around the damage to check for hidden cracks.
3. Clean the pit with the carbide probe to open the break and remove loose glass. Note: you can also use the drill for this procedure (See the section on Drilling the Damage in Advanced Repairs)
4. Remove debris by blowing air over the pit. Do not blow on damage with your mouth . Use a vacuum or syringe
5. Flex the cone, cracks, and damaged area to check for moisture. Note: Watch for dark areas in the break-these indicate the presence of moisture-and they should move easily during the flexing. Remove moisture. (See the section on Removing Moisture in Advanced Repairs.)

Note: Recent rain, car wash, or morning dew are good indicators that the damage might contain moisture.

Note: The removing moisture procedure should always be done on bull’s eyes, partial bull’s eyes, and combination breaks.

6. Sight the damage through the cylinder guide, and place the bridge on the windshield. Position the bridge so that the plunger is up or away from you so that the cylinder is closest. Pump the plunger till the red mark does not show.

Note: Adjust the tensioning wing with the knurled lock knob for best results.

7. Assemble “O” ring to the injection cylinder, screw into the bridge and seat on windshield. Observe with the mirror and turn cylinder until the “O” ring touches the glass. Turn the cylinder an additional 1/ to 1/4 turn. Tighten set screw.

Note: If the cylinder is left in the bridge when mounting, make sure that the cylinder has been backed up in the guide.

8. If working out of doors, cover repair area with the U.V. screen
9. Place resin in injection cylinder using dropper, filling the dropper to the mark. Use the mirror to check for air bubbles. Remove the air bubble with a probe. (See the section on Resins for handling)
10. Attach vacuum/pressure pump to injector. Place pump switch to the vacuum position.
11. Apply vacuum by squeezing pump handle. Observe the gauge to determine the maximum vacuum amount, and examine the break through the mirror to observe air moving out of the break. Resin will flow into the break at this time from the capillary action. Release vacuum.
12. Repeat Step 1 two to three time, and leave repair under maximum vacuum for one to three minutes, or until air is removed.
13. Release the vacuum with switch, and move switch to pressure position. Apply pressure slowly. 15-20 PSI will be sufficient for most repairs

Note: Do not over pressurize. Over pressurization will cause a pressure ring and delaminating around the damage. 5-10 PSI is often enough pressure.

14. Observe resin flowing into break, Allow 5-10 minutes. Look for resin filling hidden cracks you observed in step Two, #5. Repeats Steps 1-3, as necessary
15. If air remains in the break, or the break will not fill refer to the section on Advanced Repairs.
16. If heat has been applied, repair must be allowed to cool to ambient temperature before curing.

Note: Give the windshield repair a final inspection before proceeding.

Curing the Windshield Repair

1. Remove the U.V. screen, and use U.V. lamp even if outdoors. Allow the U.V. lamp to warm up for two minutes.
2. Cure the resin under pressure, one minute for each side of the break.

Note: Curing under pressure minimizes the effect of resin shrinkage. Cracks have a reservoir of resin to draw from in the pit. The cylinder blocks the pit from curing.

3. Release pressure at bridge connection. Place curing tab directly below the cylinder. Release suction cups by squeezing tabs and remove bridge, catching and trapping excess resin under tab over the repair.

4. Inspect repair using light, and remount bridge and repeat process as necessary.

Note: Be sure to check for trapped air in pit area. Remove air by lifting tab and dragging out of pit with probe. Remove trapped air from a drill hole with probe.

Note: Refer to Advanced Auto Glass Repairs for larger pits.

5. Place U.V. lamp over repair and cure for 5 minutes. Clean equipment and windshield while waiting. Do not attempt to cure from inside windshield because the PVB layer will block the U.V. light.

Step Six: Finishing the Repair

1. Remove tab, and scrape excess resin from windshield with razor blade held perpendicular to the glass, using a back and forth motion

Note: If the resin at the center of the pit is lower than the windshield, add resin and replace tab. Repeat curing.

2. Replace the U.V. lamp, and continue curing for 2 minutes.
3. Polish pit with pit polish and a shop towel. Finish cleaning windshield.

Your Windshield Repair is finished.