1-What is frit?
Frit is an industry term for the paint that is applied around the perimeter of
the automotive glass parts. One of the key ingredients in frit is a glass
ceramic particle that fuses to the glass surface making it a very durable and
scratch resistant surface.

1-Why is frit (paint) on the glass?
Frit serves two roles on the glass. First, it is a cosmetic feature that is used
to hide interior trim and pinchweld details. Early model vehicles used wide
moldings to obscure what would otherwise be exposed areas. As moldings
became smaller to the point of nonexistence on several current models, the
frit had a greater role in covering unfinished areas of the vehicle. Secondly,
the frit inhibits UV degradation of urethane adhesives. While the frit will
not completely block the UV rays from passing through the glass, it does
significantly reduce UV light transmission. Most urethanes are not UV
stable. If urethane is left exposed to sunlight for prolonged periods of time,
it will yellow and turn chalky. Presence of the frit will extend the lifetime of
the urethane adhesive system.

1-How many types of frit are there?
There are hundreds of types of frits developed for automotive glass
applications. The most common automotive glass frits we use are black, gray
and white although other colors are available. Frit pastes are developed to
work in combination with the processing requirements needed for a specific
part. Each paste is developed for the specific furnace time and temperature
parameters used to fabricate parts at a manufacturing location. It is not
uncommon for a glass manufacturing facility to work with a dozen different
frit pastes.

1-Why do some windshields have the paint sandwiched between the glass
plies and others have the paint on the outside surface?
The location of the frit on the windshield is usually specified by the
customer. However, it can also be influenced by the manufacturing facility
and the fabrication techniques used to make the windshield. The location of
the frit can often improve the windshield processing yields. Certain parts
will process more efficiently if the paint is applied to both the interior #2 and
the exterior #4 glass surfaces. Other parts will have processing parameters
that are best with only one surface painted, either the #2 or the #4 surface.

1-How is frit applied to the glass?
Frit is applied to the glass utilizing a silk screen method. It is very similar
to the method used to silk screen T-shirts. An image of the frit design is
developed for the glass in the bent or curved shape. Then the image is
unwrapped and flattened. A silk screen is made to allow the frit to pass
through openings in the screen. The openings correspond to the final
design image. The frit is a thick paste that is put onto the screen.
Squeegees are used to push the frit paste through the screen openings and
onto the glass. Frit is applied to the glass while it is in the flat position
before it is processed through the furnace. The furnace helps to cure the frit
and to fuse it to the glass surface. Every part with each different design has
a unique silk screen. Silk screens are constantly being maintained
throughout the life of a part. Because of the fragile nature of the screens,
they will wear out and commonly need to be remade throughout the
lifetime of a part in production.

1-Is glass considered a liquid or a solid?
Believe it or not, glass is amorphous (non-crystalline) and is considered a
liquid. When glass is in its "hardened" phase, it has a VERY slow moving
flow. You may see an example of this in very old houses with original
plate glass. Old houses have windowpanes that measure thicker at the
bottom than at the top. Glass as we know and work with it is actually in its
super cooled liquid phase.

1-Does glass ever become a solid?
Yes, glass can crystallize and become solid. For solidification of glass to
occur naturally, it takes 70 million years for this to happen. Solidification
can be accelerated by other means such as how the glass melt is cooled or
if its chemical state is altered slightly enough to change the phase of the
melt. An example of crystalline glass can be found on the inside surface of
an insulated glass (IG) unit that appears to be stained. The crystalline glass
has an opaque milky white or "frosted" appearance. It forms in the
presence of moisture that gets trapped in the IG unit. The moisture reacts
with the inside surface of glass causing the sodium to leach out of the glass.
The absence of sodium changes the melt enough to promote crystallization
of the glass. What appears to be stained glass, is actually glass in the solid
state!

1-I have a windshield that has streaks on it with prism like colors. Could
this be a damaged coating on the windshield?
Glass coatings can take on unusual appearances if the coating is damaged.
Spots of discoloration may become visible. The discolored areas are usually
most noticeable in natural lighting conditions when viewed from outside the
vehicle. Coatings are reflective, so a damaged coating would not reflect a
constant uniform color - much like an old mirror that starts to show signs of
gray areas around the edges. However, a uniform appearance of prism like
colors may be a natural condition for the type of coating that was applied to
the glass and should not be considered a defect. Some aftermarket rain slick
type products that can be applied to glass or a film build of dirt and debris on
the inside surface of a windshield could give a prism like appearance. To
eliminate these conditions, use a good glass polishing / cleaning material
such as Bon-Ami or wash with a vinegar water solution.

1-What is Batch glass?
Batch is a glass reference term that identifies a part of the manufacturing
process. The raw components of glass are properly proportioned and mixed
in batches for delivery to the furnace. Even though glass is made in a
continual process that runs 24 hours a day, every day of the year, the raw
materials are added as needed in batches. To state that a glass is batch glass,
it implies that there is not any post manufacturing materials, i.e. a film or
coating, applied to the glass. Batch glass gets all its characteristics from the
raw materials that are used to make the glass. In the case of privacy or solar
batch glass, the dark colorants and UV inhibitors are mixed in with the
original ingredients in the batch to make the glass.

1-What is Float glass?
Float glass refers to the glass manufacturing process. The raw components
of glass are melted in a furnace between a temperature range of 240OF to
2850 F. A continual process is established as the molten glass is moved from
the furnace to the tin bath where it is supported on molten tin until the glass
cools from the slurry state to a temperature where the glass becomes solid.
The float process was developed by Pilkington during 1950's and is now
considered the primary state of the art process for manufacturing automotive
and architectural glass.

1-What is the tin side and what is the air side of glass?
As mentioned earlier, the float glass process involves floating molten glass
on.molten tin. The molten tin is smooth enough to give glass its flat
surfaces. The tin and glass are like oil and water, they don't mix. However,
the side of glass that is in contact with tin during the float process does pick
up a microscopic layer of tin. This is considered the tin side of float glass.
The top side of glass is called the air or atmosphere side. To detect the tin
side of glass, hold an UV light at an angle to the glass surface. The tin side
will glow and the air side will not.

1-What are the raw components of glass?
An old alchemists equation for making glass still holds true today: fire +
sand = glass. Obviously technological advancements have altered the
equation a little bit, but today's glass manufacturing processes are based on a
centuries old technique. Other raw materials add to the characteristics that
we depend on in glass such as color, strength, and visual purity. The list of
raw materials for glass includes Silica Sand, Soda Ash, Dolomite,
Limestone, Salt Cake or Gypsum and Rouge. A certain amount of recycled
glass, called cullet, is also used to make new glass.

1-What is Soft-Ray and what is Solar-Ray'?
Soft-Ray and Solar-Ray are GM Trademarks for the glass used in their
vehicles. It identifies the TYPE of glass used for construction and can
appear on either laminated or tempered glass. LOF uses E-Z-Eye glass for
the production of Soft-Ray parts and EZKool solar control glass for Solar-
Ray parts. PPG uses Solex and Solar Green respectively. Deep Tint Solar-
Ray is another GM trademark that appears on dark colored solar control
parts.

1-How can I determine if a part has Lead-Free paint on the glass?
There is not an easy method to identify whether a part was manufactured
with leaded or unleaded paint. Many glass fabricators now use unleaded
paints to comply with industry hazardous waste disposal regulations. The
best recommendation for preparing a part for installation is to clean the
painted areas thoroughly. Then prime the glass according to the adhesive
manufacturers recommended procedures for installation.

2-What is the difference between the DQ8425 and DQ9195?
The difference is in the latch assembly for these parts. These are both
swing-out rear quarter windows for the Chevy/GMC ST light pickup. The
DQ8425 fits the standard two-door model. The DQ8425 latch assembly is a
common straight latch. The DQ9195 fits the new three-door pickup which is
also known as the Highlander model. The latch assembly on the DQ9195 is
curved. The curved latch assembly will allow the swing-out to open wider.

2-The encapsulation around the striker/ handle area on the lift glass for
the 1997 Chevy Blazer 4 door has come loose from the glass. Can the
encapsulation be reattached to the glass?
As a rule, encapsulation should not be reattached to the glass if it has come
loose. In many cases, the encapsulation helps form the sealing and the
attachment method for the installation of the part. A break between the
encapsulation and the glass could lead to water leaks, wind noise or system
failure. In this case, the handle and the striker area are bonded to the glass
with the encapsulation. The structural integrity of the striker attached to that
glass would be weakened and would have unpredictable performance if the
encapsulation bond were broken. For optimum performance of the
encapsulated assembly, it should be replaced and not repaired.

2-What is a monogram?
A monogram is often referred to as the bug or trademark. Every automotive
piece of glass is required by law to have an identifying mark on the glass
that will be visible once that glass is in the correctly installed position in the
vehicle. These marks are usually painted on the glass, but they can also be
sand blasted or acid etched into the surface.

2-What is in a monogram?
For automotive applications, there are certain governmental items that must
be in the monogram including a department of transportation (DOT)
number, the model (M) number and the glass type (AS-1, AS-2, AS-3 etc.)
Monograms can also include information such as the brand name of the
glass, the company name that made the glass, the company logo, the country
of origin and a date code identifying when the glass was manufactured.

2-Is there anyway to determine what a part is by the monogram on the
glass?
Unfortunately, the majority of monograms do not have any information in it
to help determine what an unmarked part is. However, we are starting to see
more parts marked with the NAGS number in the Monogram. As more of
this is done, it will be easier to correctly identify unknown parts.

2-What is the difference between AS-1, AS-2 and AS-3 glasses codes?
For automotive applications, the three most common types of glass are AS-
1, AS-2, and AS-3. All windshields must be marked with the AS-1 code
which is on laminated glass having light transmission greater than 70%. All
tempered glass that has light transmission above 70% is marked with an AS-
2 code. All glass, laminated or tempered, that has less then 70% light
transmission will have an AS-3 Code.

2-What is a DOT code?
The DOT number identifies the glass manufacturer. The acronym DOT
stands for Department of Transportation. Each glazing manufacture must
apply for a DOT number in order to sell glazings for vehicles in the United
States of America. Each DOT number is assigned by the government and is
unique for every manufacturer. Every piece of glass that is made must
contain that DOT code if it is to be sold in the automotive market.

2-What is an M number?
The M number is a model number that is assigned by all glass manufacturing
companies. Each company establishes their own M number system that is
unique to that organization. The M number identifies the specific glass
construction. It can identify the glass details used to manufacture a part such
as glass color and thickness. One Model number might apply to 50 different
part numbers. Each Model number is tested every year for compliance with
the governmental regulations. Most of the time, a part number cannot be
determined by the M number.

2-How do I measure block size?
Follow these steps and you should be able to obtain an accurate block size
measurement.
• Lay the part flat on a table. Square the part up in front of yourself.
• Imagine a box drawn around the part. The dimensions of the box should
touch the widest point on each side of the part.'
Measure the BOX height through the center of the glass with the tape
measure on the glass to account for glass curvature.
• Measure the BOX length through the center of the glass with the tape
measure on the glass to account for glass curvature.
REMEMBER: Glass block is the size of the glass when flat. To
accurately measure height and length, you must account for glass
curvature.

2-How can I determine whether the glass in a car is original or a
replacement?
If you don't know the history of the car, one-way to identify a piece of glass
is to check the monogram on the glass. If you. Knew the manufacturer of
the original glass, check the DOT (Department of Transportation) number
on the glass in the car. If the DOT number doesn't belong to the OE glass
supplier, then the part was a replacement. If the number does match, then
check the date code on the glass. Most manufacturers mark the monogram
with a means of identifying the month and year of glass production,
sometimes even the date and shift! Since each company does it differently,
you'll have to contact the appropriate manufacturer for their date code
conventions, which can include combinations of letters, numbers or even
dots over various letters. By comparing the date of the glass with the date
of the car assembly, you can determine if they are the same vintage. If the
glass date closely matches the vehicle assembly date, chances are the glass
is original.

2-Where can I find a DB8311 or DB8312 GP?
The green privacy (GP) DB8311 and DB8312 made for the 1993 and 1994
Chevy / GMC Suburban are no longer available. During that time, the
glass industry was developing solar batch privacy parts, which are now
gray privacy (YP) parts. The batch privacy parts have displaced the coated
privacy and offer superior performance characteristics. The only
alternative to achieving a color match when replacing an original GP part
with a YP part is to replace the neighboring part. Many times, GM will
authorize the replacement of the neighboring part under warranty at no
charge to the customer.

2-Why was the hardware flag on the DB8592 and DB8593 recently
changed from N to Y? Are these parts now sold with moldings?
These parts are sold with a grommet in the wiper hole in the glass. The
hardware flag does not automatically mean moldings. The grommet is a
small black rubber piece that seals out water when the wiper is attached
through the glass. The parts have always been made with the grommet;
however, it was not until recently that the grommet was considered
hardware. The hardware flag has been changed from N to Y on the
DB8592 and DB8593 as well as the DB81 16, DB8117, DB7942 and
DB7943.

2-What are the glass part numbers for the GM extended pick-up trucks
with the third cab door option?
The third door option is really a side panel that has the ability to open. The
design incorporates the existing quarter glass parts. When replacing the
glass, order the same part number that would be required for the standard
extended cab without the door option. Also note, the third door could be
equipped with either the stationary or the swing-out quarter windows.

2-What is the difference between FB3984 and FB3924?
The difference between these two parts is the paint band artwork that is on
each of them. The FB3924 fits the GEO Tracker 2 and 4 door utility
vehicles. The FB3984 fits the Suzuki Sidekick 2 and 4 door utility vehicles.
The FB3984 has an insignia saying "SUZUKI" across the top of the backlite.
While the artwork is different, the glass size and shape is the same for both
parts.

2-What is the difference between the DW1026, DW1 159 and DW1199?
The DW1 026 is a non-solar windshield. The DW1159 is the solar version
of the DW1026. The DW1199 is also a solar windshield, but the mirror
bracket has been moved down to make room for the overhead console that is
in the cab of the truck. The DW1 199 is a one way interchange with the
DW1159. Solar parts are not interchanged with non-solar parts, but the
DW1199 will fit the DW1026 opening and can be used as an upgrade.

2-What is the difference between the DW1217 and the DW1199?
GM Truck and Bus made engineering changes to the full size Chevy / GMC
Truck and Suburbanize. They modified both the door and windshield seal
making it a tighter fit to reduce the wind noise during the 95-model year.
The DW1217 has a modified encapsulation design with a flexible bulb seal
added to the edge of the side pillars on the windshield. The DW1199 should
not be put into a DW1217 vehicle.

2-What causes the DW1293 to break at the top of the windshield?
The cause of breakage is attributed to an expansion / contraction issue in
cold weather. The break occurs at the location of the antenna connector on
the glass and usually in a crescent or half moon shape. The problem has
been corrected and a new adhesive system is being used to bond the antenna
connector to the glass. If you are replacing a DW1293 due to breakage at
the connector, it could be eligible for GM warranty service.

2-What part number do I need to replace the manually operated quarter
swing-out on the 96-97+ model years of the Chrysler mini-van?
Actually the glass for the manual and the power quarter windows is the
same. The difference is the latch assembly required to attach the part into
the body opening. The glass assembly is supplied ready to install for the
power window option. To convert the glass for the manual assembly, it is
recommended that a new manual latch be purchased The manual latch part
numbers are 4797154 (right hand) and 4797155 (left hand). The power latch
ball retainer must be removed from the glass. The manual latch must then
be threaded onto the stud until the latch starts to bottom out against the stud
base. Once the glass is installed at the hinge area, the latch can be adjusted
to align the mounting holes. Don't forget to tighten the latch down after it’s
installed!

2-Why aren't DW1021 and DWI 130 interchangeable?
These parts are not interchanged because of safety reasons. While its true
that they look a lot alike, they are very different. The DW1 021 is made
with a thick PVB innerlayer. The car design, which includes the Buick
Skyhawk, Cadillac Cimarron, Chevy Cavalier, Pontiac Sunfire and
Oldsmobile Firenza needed the
glass and plastic strength of the windshield to help pass the federal roof
crush test requirements. On the 1992 and newer models, the vehicles were
built with stronger A pillars. These vehicles were able to pass the tests using
a windshield construction of standard thickness innerlayer. The DW1 130
has a thinner PVB than the DW1 021 and should not be used on early model
vehicles

2-What does the reference L WB mean in the foreign NAGS Car Glass
Parts Catalog? In the 1996 catalog, LWB indicates Long WheelBase. It is
noted on the 95 plus model years for the XJ6 and XJ12 Jaguar Sedans. The
rear doors and back glass parts are different on the long wheel base models.
The LWB models offer more room in the back seat resulting in a wider back
door. To identify the LWB vehicles, measure the width of the rear door
glass. The LWB requires a wide glass part that measures 35.5 inches!

2-What is the hardware that has been added to the DB8486 and DB8487?
There are three set blocks added to the glass to eliminate a Buzz, Squeak and
Rattle problem with the ' vehicle build. The setblocks are located along the
bottom inside edge of the glass. To install, match the tabs on the set blocks
to the corresponding tabs on the rear shelf panel.

2-What is the difference between the DW1283 and the DW1284 moldings?
There is a difference between the DW1283 and the DW1284 moldings that
are attached to the glass. The molding for the DW1284 has design styled
notches in it. The two moldings fit into the opening differently and are not
interchangeable.

2-What is the hardware sold with the DB8930, DB8931, DB8932 and
DB8933?
These parts are sold with a grommet in the wiper hole in the glass. The
grommet is a little black rubber piece that seals out water when the wiper is
attached through the glass. Moldings for these units are sold separately.
Moldings on the Chrysler minivan lift glass can be salvaged and reused.
However, if you prefer to use new moldings they are available.

2-Which side of the vehicle is the right hand side?
The RIGHT hand side of the vehicle is the PASSENGER'S side of the
vehicle. The DRIVER'S side of the vehicle would be the LEFT-hand side.
Rule of thumb, right and left sides are determined by picturing yourself
sifting in the car.

3-Are there any hints for color matching the gray privacy glass needed in
a vehicle?
One of the best recommendations for color matching privacy glass is to
record both the DOT and M numbers from the original glass. The DOT
number will identify the glass manufacturer and the M number will indicate
the specific glass construction used for the part needed. Several glass
manufacturing companies, including LOF and Carlite, have developed batch
solar control privacy glass. Because of the manufacturing efficiencies of
batch versus coated glass, the demand for coated glass is declining. Older
varieties of coated glass are now extinct and cannot be found.

3-My customer needs a gray privacy quarter window for the 97 Ford
Explorer, but the color doesn’t match. What should I do?
Confirm the part number that is being ordered. If the part you need doesn't
have a mirror like finish, chances are you need to order one of the newly
assigned part numbers for Carlite's new batch privacy glass. Since March
1997, Carlite has been manufacturing batch privacy glass for the 97 Explorer
and Expedition. The batch privacy means the appearance is determined by
the glass composition when the glass is originally formed. Previously, the
privacy Carlite glass was a pyrolyticly coated product that had mirror like
characteristics. New part numbers were issued for the batch privacy glass.
Carlite has announced that they will continue to offer both the batch and
coated parts for these vehicles. The new part numbers for the Carlite
BATCH privacy glass are:
'97 Ford Explorer '97 Ford
Expedition
DD9291/2 YPY DD9133/4YPY
DQ9295/6 YPY DV9135/6YPY
DQ9289/90 YPY - (2 door) DQ9139/40YPY
DV9293 / 4 YPY DQ9141/2YPN
DB9297 YPN DQ9148 YPY
DQ9301 YPN
DB9156 YPY

3-What are KP color-coded parts?
The KP color code refers to Black Privacy. One way to manufacture a black
privacy part is to apply the paint that is normally used only on the perimeter
of a glass part across the entire surface of the part. The KP color option is
now available for several of the rear quarter and back glass parts for the new
GM Mini Vans including the Chevy Venture, Oldsmobile Silhouette, and
Pontiac Transport.

3-Why is a KP black privacy glass used on the vans?
The main application of black glass is on cargo industrial vans where
privacy is desired in the rear of the vehicle. These dark glass units were
chosen by the vehicle designers at GM as the economic alternative to metal
panels for the cargo van options. The black privacy glass option is available
at time of vehicle order.

4-When should a non-conductive adhesive be used?
If the adhesive will contact the antenna or defroster lines when the part is
installed, use a non-conductive adhesive. Non-conductive adhesives prevent
interference with antenna systems and heated defroster systems that are
contained in the glass. Many new glass parts have the antenna, defroster
connections or buss bars around the edge of the glass in the same area that
the adhesive is applied to install a glass part. Using a conductive adhesive
will affect the performance of the electrical system. Several adhesive
manufacturers offer a non-conductive product for these glass applications.
Be sure to follow the manufacturers specific instructions for the adhesive
system you use.

4-How can I R & R an encapsulated windshield?
A skilled technician can remove and reinstall an encapsulated windshield
with the use of a power cutout knife. Salvaging an encapsulated part will
take practice - you can develop the skill with old parts that need to be
replaced with a new windshield. When cutting out the windshield, use a
power tool and blade designed to cut from the interior of the car. There are a
few tips which you can use. Wrap tape around the blade sheath to act as a
spacer between the blade and the glass surface. This will maintain a safe
distance between the glass and blade and help avoid scratching the paint on
the glass surface. It will also help a technician avoid cutting encapsulation
on the inside surface of glass. Also, try cutting out the part with the beveled
edge of the blade toward the glass. This will force the blade away from the
glass, but be careful not to cut or scratch the pinchweld. This is a method
that needs to be practiced.

4-Can pinchweld rust cause problems with installation of a windshield?
Most definitely! If there is any evidence of pinchweld rust that is found
during an installation it needs to be taken care of prior to replacement. Rust
will continue to flake unless totally removed. If adhesive primer is applied
to rust, the primer will flake off with the rust leading to a potentially unsafe
installation. Problem rust areas should be documented and discussed with
the vehicle owner before installation. Preparing the pinchweld after the rust
is removed also requires special treatment. Check with your adhesive
manufacturer for the recommended surface treatment for pinchweld
preparation.

4-Is it true that if I cover up a pinchweld scratch with primer that it won't
rust? No, contrary to common practice and popular belief, there is not a rust
inhibitor in pinchweld primers. At best, the adhesive over the primer forms
a watertight seal that delays the rusting process. Eventually, water will find
its way into the pinchweld and will start to rust scratched areas. The best
way to inhibit rust is not to scratch the pinchweld to start with. TIPS: Hold a
utility blade at an angle to the adhesive bead while cutting. This will keep
the blade tip from contacting the back wall of the pinchweld. Also, try
rounding the comers of the pinchweld scraper with a file. Use the scraper
with the beveled side down which keeps the scraper from gouging the paint
on the floor of the pinchweld.

4-What is the string used for in the molding on the FW655?
The string was designed to help a technician with removal of the FW655.
Located at the bottom of the windshield, the string can be used to cut the
windshield out of the opening. The string is actually a fiber cord that is very
strong. When pulled straight from the urethane and held parallel to the
glass, it can be effective for removing this part. However, it is a specialized
removal method and it may take some practice to achieve desirable results
with the cord

4-How do installation methods cause stress cracks?
Installation related cracks usually result from a short cut out method, where
all of the old urethane bed is not removed prior to installation. If the shape
and form of the new glass is not identical to the old urethane bed, the glass
could have spots of interference on the adhesive that lead to breaking.
Installation related stress could also be formed by using adhesives that are
too rigid and don't offer the compression and flexibility required of the
adhesive system. Usually, installation related stress cracks would develop
over time after the adhesive has been allowed to fully cure.

4-Can a scratch removal process change the color of privacy parts?
Depending on the composition of the privacy glass, it is possible that a color
difference could be detected. The most obvious color change would result
from the removal of a pyrolytic coating that gives the part its privacy
properties. These coatings are usually applied to the inside surface of glass
and should not be scratch polished. The batch privacy parts are colored
throughout the thickness of the glass. Removing a layer of glass thickness
reduces the amount of color intensity and can result in a lighter area where
the scratch was polished out. Please note: if enough glass is removed so that
a color difference can be detected, there will probably be areas of optical
distortion develop. Distortion can result from the dimple left in glass by the
polishing system.

4-My customer sees streaks on their new windshield when they use their
old windshield wipers. Do you have any suggestions to eliminate this?
The answer is as simple as installing new windshield wipers. Wipers are
made of plastic or rubber that take a set in the heat to the surface they are in
contact with. Glass surface changes, even small differences between the old
windshield and the new one, are sufficient enough for the wipers to act
differently on the new windshield. After time the old wipers may eventually
take a set to the new windshield, but for safe visibility, recommend that they
install new wipers. When putting new wipers on the vehicle, make sure the
glass is cleaned well: this way, any dirt and grime that was deposited on the
glass from the old wipers won't be picked up by the new ones. HINT:
Weekly washing of wiper blades with white vinegar will prolong the life of
the wiper. It helps keep the blade cleaner so it will work most efficiently.

5-What is tempered glass?
Tempered glass is a single piece of glass that is strengthened through a rapid
cooling process. This cooling process tempers the glass by blasting both the
top and bottom surfaces with air. The outside surfaces of the glass cool
faster than the core of the glass. This action sets up a balance of strains
between the surfaces and the core which adds considerable strength to the
glass. Tempered glass is difficult to break, but if broken it breaks into small
granular pieces.

5-How are tempered parts made?
Glass of the specified thickness is cut to the desired size. Any artwork or
paint
design is applied to the glass while it is in the flat position. This includes
any
heated grid lines or antenna lines required on the final part. The glass is
loaded
into a furnace and is heated to temperatures of 12,000 F. There are multiple
processes that could be used to bend the glass as it exits the furnace
including roll.

5-How much force is required to break a tempered backlite?
While the strength of tempered glass can seem very high, it is important to
recognize that the manner in which tempered glass is broken will affect the
strength. Tempered glass is extremely difficult to break with dull, blunt
objects. Tempered glass can have a rupture strength of up to 24,000 pounds
per square inch. Recall that tempered glass is produced by rapid cooling of
the outside glass surfaces which sets up a stress / strain balance

5-Why do the heated grid lines on heated backlites sometimes have a redbrown
color and other times have a yellow color?
The color of the grid lines is predominately determined by the surface of
glass that they are printed on. The lines will have a dark appearance when
printed on the tin side of glass. The lines will have a brighter yellow or
amber color when printed on the air side of glass. Other colors, such as
white or light gray, may indicate a potential manufacturing problem with the
heated grid lines such as an under fired
condition or too much silver. These can result in a heated backlite that does
not function correctly.

5-Is it a defect to see discolored spot patterns on tempered glass?
No, the discolored spot patterns on a piece of glass are actually a
phenomenon of the tempering process. During tempering, air is forced onto
the glass through hundreds of nozzles. The spots are areas where the cool
air contacts the glass. The temper spot pattern can indicate how well a piece
of glass is tempered. The size and consistency of the discolored areas will
vary with the exact process used, but they are present on all tempered parts.
The ability to see these patterns is dependent on the angle ' of installation
and the lighting conditions. For example, it is easier to see the patterns on a
sloping piece of glass at dusk than it is to see them on a vertical piece in
bright sunlight.

6-What is an Innershield?
The innershield is a layer of plastic on the innermost piece of glass which
was most commonly used on the windshield. The innershield prevented
lacerations on an occupant's head and face if they came in contact with the
windshield in the event of an accident. The innershield was a popular option
on deluxe vehicles about ten years ago.

6-What is the difference between the DW1216 and the DW1307?
The difference is light transmission. Both units are manufactured with solar
control glass. The DW1216 has been made to meet the US standards for
light transmission, which must be greater than 70%. The Chrysler DW1307
is made to meet European light transmission requirements, which must be
greater than 75%. These parts do interchange; the DW1 307 can be used for
DW1216 applications.

6-If an innershield part needs to be replaced, is it available on a
replacement? Unfortunately, most of the parts that were originally made
with an innershield are not currently available. The innershield can be
replaced with a non-innershield windshield. These interchanges have been
done for a couple of years now. It is not considered a violation of safety
standards to replace an innershield with a non-innershield product.

6-How is a shadeband put into a windshield?
The shadeband is pre-tinted onto the plastic that is placed between the glass
plies. The plastic comes in rolls and one end of the roll has the shade color.
During processing, it may be required to warp the plastic to curve the
shadeband so it will match the curve of the top of, the windshield. After
warping, the plastic is cut to size and it is ready to use.
.

6-What is delamination?
Delamination is the separation of the glass plies and plastic layer in a
laminated product such as a windshield. This is also known as an unbonded
area (UBA) or an oil blow. Old autoclaving process used hot petroleum to
laminate windshields and the oil could seep into the edges causing the
windshield to delaminate

6-What is bullet proof glass and how is it different from bullet resistant
glass?
Bullet proof glass is glass that will stop a bullet. Any bullet. To make a
glass bullet proof, every type of bullet from every type of gun must be taken
into consideration during the design of the glass. Bullet proof glass is
actually a composite of glass and plastic layers laminated together to achieve
a strong composite that will stop a bullet. Bullet proof glass will be three or
more inches thick. Bullet resistant glass is designed for applications with a
resistance to a range of specific bullet calibers. Bullet resistance glass can
be obtained in a 3/4 inch thick composite of glass and plastics laminated
together. On vehicle applications, the environmental end use is considered
for the glass design. If a vehicle is outfitted with bullet proof or bullet
resistant glazing, all the interior trim must also be reworked to accommodate
the thicker glass.

6-Why is my windshield wavy and distorted when I look through it from
the side? This distortion is called cross-car distortion. It is most noticeable
when you are turning and looking through the right side of the windshield at
other vehicles. Cross-car distortion occurs when looking through the glass
at an angle. When the vehicle glass part is designed, the manufacturer tries
to minimize both the optical distortion (distortion when looking straight
ahead) and cross-car distortion. It is normal for some amount of cross-car
distortion to be present in the glass. As new glass parts become bigger with
deeper corner wraps and set at lower more aerodynamic angles in the
vehicles, the cross-car distortion may become more noticeable. Most
importantly, optical distortion will not change and will remain minimal
because drivers look straight ahead much more than to the side.

6-How is the location of a shade band in the windshield determined?
The shade band is located along the top of the windshield, starting at the
edge which meets the roofline of the auto and goes toward the center of the
glass. The driver's primary viewing area of the windshield is considered the
AS-1 area and must have at least 70% illuminate light transmission required
by Federal Motor Vehicle Safety Standard (FMVSS) 205. The area where
the shade band is located does not meet the- 70% light transmission area and
must be located above the drivers primary viewing area. The primary
viewing area is determined by the vehicle manufacturer using the
recommended guidelines in Society of Automotive Engineers (SAE) J 1 00 -
Passenger Car Glazing Shade Bands. This area is noted on windshields by
an AS-1 mark and an arrow pointing towards the primary viewing area. The
position of the mark is specified to the glass manufacturer. The AS-1 and
arrow mark is then printed directly onto the glass surface by the glass
manufacturer during the assembly process. The shade band must be located
above that AS-1 mark.

6-What is the location tolerance of the shade band from the AS-l?
Tolerances will vary from depending on the vehicle and the glass
manufacturer. The end result of the location of the shadeband is actually a
combination of tolerances. The location of the AS-1 mark has a slight
tolerance which can be 1 to 2 mm. The tolerance for the bottom edge of the
shade band location is 0.0 mm lower than the AS-1 mark up to 20.0 mm
above (toward the roofline) the AS-1 mark. The fade of a shade band from
clear to color is usually specified to be a maximum of 10.Omm. When a
windshield is constructed, the shaded area is positioned above the AS-1
mark. The overall tolerance can be as great as one inch although statistically
the variation is not as great as the tolerance band provides.

6-What are stress cracks?
Stress cracks are breaks from the edges of laminated glass, such as a
windshield, that happen without an impact point or noticeable damaged
area. While this phenomenon can occur with seemingly no apparent cause,
there are however, two major factors that have a role in creating stress
cracks. The stress crack can be caused by a manufacturing defect within
the glass or it can be attributed to the installation methods.

6-How do glass defects cause stress cracks?
Stress cracks can occur if the two plies of glass used to make the laminated
part are not completely homogenous with each other. Stress cracks can be a
condition of tension or compression that exist within the glass. Stress can
also be caused by incomplete annealing or temperature difference between
the plies. Manufacturing processes include multiple quality checkpoints for
every individual part during production to identify and eliminate defective
parts. Even so, it can be difficult to predict a stress crack due to
manufacturing conditions

6-I have often heard of a windshield surface referred to as the number 1,
2, 3 or 4 surface. What do these numbers mean?
The windshield surface number refers to the glass surface of the individual
glass plies in the laminated composite. A basic windshield construction is
composed of two pieces of glass with a plastic layer in between. The
surfaces are counted from OUTSIDE the vehicle. Therefore, surface
number 1 is the outside surface of the exterior glass piece that would be
exposed once installed in the vehicle. Surface number 4 is the innermost
surface which would be on the interior of the vehicle once installed. Surface
number 4 is the surface that is prepped with primers, cleaners and or
activators required for installation. Surface # 2 and 3 are interior surfaces
that are in contact with the plastic.

6-What is laminated glass?
Laminated glass is constructed of two pieces of glass with a piece of plastic
in between the glass plies. One type of plastic innerlayer used is PVB or
polyvinyl butyral. Laminated glass is required to make windshields in the
US.

6-I've been told you should not repair heated windshields. Can the current
model Chrysler heated windshield - DW1225 or DW1226 - be
repaired'?
Yes these parts can be repaired! The Chrysler minivan windshields,
DW1225/6, are not traditional heated windshields. These windshields are
equipped with a Heated Wiper Park Area. The heated area simply heats the
windshield wipers keeping them frost-free. The intent of the heater is not to
defrost the entire windshield like traditional heated windshields. The heater
grid on the DW1225/6 is on the inboard lite and resembles the defroster grid
that is put on heated backlites. A repair is usually performed on the
outboard lite and should never come in contact with the heater grid. When
in doubt about REPAIR vs REPLACE, it’s always the safest bet to replace
the windshield.

6-I've been told you should not repair heated windshields. Can the current
model Chrysler heated windshield - DW1225 or DW1226 - be
repaired'?
Yes these parts can be repaired! The Chrysler minivan windshields,
DW1225/6, are not traditional heated windshields. These windshields are
equipped with a Heated Wiper Park Area. The heated area simply heats the
windshield wipers keeping them frost-free. The intent of the heater is not to
defrost the entire windshield like traditional heated windshields. The heater
grid on the DW1225/6 is on the inboard lite and resembles the defroster grid
that is put on heated backlites. A repair is usually performed on the
outboard lite and should never come in contact with the heater grid. When
in doubt about REPAIR vs. REPLACE, it’s always the safest bet to replace
the windshield.

6-How are windshields made?
Two separate pieces of glass are cut to size. While the glass is flat it is
printed with the artwork design (frit) that's required. The glass is put
through a furnace to soften the glass and fire the frit to the glass surface.
Once the glass reaches the right temperature, it is molded into shape and
then cooled. After shaping, the glass/ plastic/ glass sandwich is put in a
clean room and then put into an autoclave. An autoclave is like a giant
pressure cooker. The high pressure squeezes the glass and plastic together.
The higher temperature softens the plastic, which bonds the glass and plastic
layers together. Once the glass exits the autoclave, any excess plastic is
trimmed and the mirror mount is applied to the glass. The glass is inspected
and cleaned several times throughout the entire process to make sure it has
been manufactured to the highest quality standards. After a final inspection,
the finished part is now ready to ship.

6-What is the Breakaway Bracket?
Several new GM and Ford windshields have a Breakaway Bracket. This
refers
To the mirror button on the windshield. This style mirror button allows the
rearviewmirror
to snap off when the passenger air bag is deployed. If the rear
view
mirror did not snap off, there is a possibility that the mirror could puncture
the air
bag rendering it ineffective. The accessory tool used to remove these snap
off rearview
mirrors is the MB-4. TIP: Put Breakaway rearview mirrors back on the
glass
before installing the windshield. This will prevent moving a newly installed
windshield out of place with the force required to snap the mirror on the glass

6-How is a windshield glass molded into shape?
There are two common practices for shaping a windshield, gravity bending
and press bending. Gravity bending has been used longer than press
bending. For gravity bending, two pieces flat glass ride through the furnace
on a mold contoured like the finished part. As the glass softens, the force of
gravity pulls the glass into shape. This pair of gravity bent glass is then kept
together throughout the rest of the windshield process. In a press bending
operation, the single lites of glass go through a furnace on a flat surface of
high temperature resistant rollers. As the glass exits the furnace it is quickly
pressed into shape between a male and female mold contoured like the
finished product. The glass is then cooled and moved to the next process.

6-What is the difference between the FW807 and FW2020?
The difference between these two parts is the mirror bracket. The mirror
bracket on the FW807 (and FW808, which is the heated version) is a
ROUND bracket. The mirror bracket on the FW2020 (and FW2021 heated)
is a SQUARE bracket. The square brackets are used on vehicles produced
from May 95 on.

7-What are the wires for on the DW1293?
The terminal connector on the DW1293 is for a radio antenna system. This
part does not have a traditional antenna system achieved by wires in the
lamination or by printed circuits on the surface of the glass. The antenna is
achieved by a conductive film that coats the interior surface of glass within
the lamination. This same metallic coating also gives the glass its solar
performance characteristics. If you look closely, you might be able to see
the antenna circuit in the shaded portion of the windshield.

7-Why is there an electrical connector on the DW1253?
The connector on a DW1 253 is for a Remote Keyless Entry option on the
1996 Mercury Villager. It is not for an antenna system in the windshield.
The DW1253 is often misidentified because of similar appearance to the
antenna windshields, DW1207 and DW1 144. The difference among these
parts is the wire which is present in the center of the antenna windshields is
not present on the DW1253.

7-Is there a special place to mount the rain sensor to work properly?
The rain sensor needs to be mounted in the path of the windshield wipers.
The rain sensor is electronic and will be attached with a connector wire -
very similar to the antenna or lighted rear view mirror connectors. Make
sure to mount the rain sensor module where the electrical plug will connect.
Some of the windshields have a cutout in the paint band to indicate where
the replacement unit should be located.

7-Why doesn't the Cadillac windshields indicate that they are Rain Sensor
compatible in the monogram?
The Cadillac rain sensor module is an optional upgrade for the vehicle. The
rain sensor windshields, DW1 227, DW1 228, DW1 229 and DW1 230, are
made to function in both the vehicles that have the rain sensor and those that
do not have a rain sensor. Since the replacement windshield will work for
both cases, a special call-out in the monogram is not needed.

7-How can I tell if my customer needs a DW1224, DW1225 or a DW1226?
The differences can be found in the monograms. These windshields fit the
1996 + model years of the Chrysler Mini-Van. The DW1224 is a non-solar,
non heated windshield and is identified with a T (for Tinted) in the
monogram. The DW1225 is a non-solar, heated windshield and is identified
by a TH (for Tinted and Heated) in the monogram. The DW1 226 is a solar,
heated windshield and is identified by a SH (for Solar and Heated) in the
monogram. By looking at the monogram in the original windshield, you
will be able to easily identify what part is needed for replacement. FYI -
Chrysler reports that the most common option is the DW1 226, the solar
heated windshield.

7-Why shouldn't the traditional heated windshields be repaired?
Traditional heated windshields have a conductive coating on the glass
surface that is sandwiched between the glass and plastic innerlayer. This
coating performs like an electrical cord and conducts the energy required to
defrost the entire windshield. When the outboard glass breaks, the film also
breaks causing a short. The repair spot would create a hot spot and could
eventually cause the windshield to overheat. There have been reported cases
of lead wires and plastic cowls melting and damage to the electrical system
from heated windshields not operating correctly. Heated windshields should
be REPLACED and not repaired.

7-If a heated windshield is no longer available, can a non-heated
windshield be installed?
Several of the heated windshields for popular vehicles, including Ford
Taurus and Sable, are no longer offered. A non-heated windshield can be
used to replace the heated part. However, THE VEHICLE
MANUFACTURERS' RECOMMENDED PROCEDURE FOR
DISCONNECTING THE HEATER CONTROL UNIT MUST BE
FOLLOWED. Carlite recommends that the vehicle be taken to a Ford
Motor Co. dealer and that the heater control unit be disabled prior to the
installation of a conventional windshield. By not disabling the heated
windshield control unit, problems may develop with the vehicle's electrical
system.

7-My customer needs a DW1135 for a 92 Pontiac Bonneville. Where can I
find one?
Unfortunately, this windshield is no longer available. This part was a
special design that had both heated and heads-up-display (HUD)
characteristics. There were very few cars actually produced with this
windshield. For replacement purposes, either a DW1106 which is a heated
windshield or a DW1134 which is a HUD windshield can be used in place of
the DW1135. Ask the customer which option they prefer - the HUD or the
heating ability. They will probably agree that the HUD is used much more
frequently and that would be the replacement choice. Remember, if the
HUD only windshield is used, the heater control unit must be disconnected
according to the manufacturers procedures (see above) to prevent electrical
problems from occurring.

7-How can I determine if a diversity or non-diversity antenna backlite is
needed? The diversity antenna will use a combination of antennas in order
to perform efficiently. Most diversity-antennas are offered with vehicle
upgrade packages. A standard car model may only have the mast antenna,
whereas the deluxe luxury package may incorporate a diversity antenna in
the backlite with the mast antenna. How to determine the need for a
diversity antenna will differ depending on the vehicle. The current Toyota
Camry has extra speakers (6 total) on the vehicle that uses a diversity
antenna and only 4 speakers on the vehicle that uses the non-diversity
antenna.

7-Can an antenna or heated backlite clip be reattached to the glass if it has
fallen off?
Clips, or tabs, can be reattached to the glass. In order to determine if the
connection is repairable, the surface of the glass must be evaluated. If there
are any chunks of glass (called spalls) missing from the surface, the repair
should not be made and the glass should be replaced. Spalls will weaken the
glass and could eventually result in glass breakage. Next, select the
adhesive to be used to reattach the clips. There are a few companies that
manufacture a conductive adhesive system that can be used to reattach the
tabs. The adhesive must be conductive so it will allow the electrical current
pass between the lines on the glass and the vehicle. Follow the
manufacture's directions for the repair. Regular super glue adhesives will
not work because they are non-conductive. HINT: Be sure to clean both the
glass surface and the clip surface of old debris. Also, let the repaired part sit
for the recommended cure time so the adhesive bond is fully developed.

7-What rain sensor replacement kit is needed for the 1997+ models of the
Buick Park Avenue?
The Buick Park Avenue uses the same GM rain sensor attachment kit that is
used for the Cadillacs with the rain sensors. The kit has an OE part number
of 25645365. Both of the Park Avenue windshields, DW1296 and DW1309,
are rain sensor compatible for this vehicle. The rain sensor is an option for
the vehicle, so be sure to ask your customer if they have this option when the
job is booked.

7-Why is there a hole for the Geo Metro and Suzuki Swift back glasses?
The hole is for a wiper that was an option on some of the vehicles. The parts
that fit these vehicles FB3929, FB3930, FB3937, and FB3938 are all
produced with a hole for the wiper. In the cases where the vehicle does not
have a wiper, there is a wiper plug that can be purchased separately to fill
the hole.

7-Why do some DW1225 and DW1226 windshields have different heated
gridpatterns?
The 1996 model year Chrysler Minivan windshields were designed with a
narrow style heated grid pattern. There was an engineering design change
that resulting in the wider heated grid design on newer DW1225 and
DW1226 windshields. The change is cosmetic and does not affect the
functionality of the windshield. Chrysler no longer offers the old design.
The new wider design is being substituted for the original part design.

7-Will a broken heated grid line on a backlite affect the operation of the
antenna?
Many new radio and cellular phone antenna designs are incorporated into the
heated grid design in the backlite. If a heated grid line is broken it will
affect the performance of the antenna. The line break will become more
noticeable with the general public as diversity antennas gain popularity and
reduce the need for traditional mast antennas. There are aftermarket grid
line repair systems available which can restore both the heating and the
antenna characteristics of the grid line.

7-What is a Rain Sensor windshield?
Several vehicle manufacturers, including Cadillac, Mercedes Benz and
BMW, are now offering Rain Sensor windshields. The rain sensor is
actually a small electronic device mounted to the inside surface of the
windshield. The device has a lens that will detect the presence of moisture
on the outside surface of glass. When moisture is present, a signal is sent to
the wiper control that automatically activates the windshield wipers. This a
great safety option for those misty periods when a driver is passing trucks
and road spray hits the windshield. The windshield wipers will activate
without the need for the driver to remove his hands from the wheel or his
eyes from the road.

7-Does the rain sensor module come on the replacement windshield?
No. At this time, none of the rain sensor designs require the sensor to be
applied by the manufacturer on the replacement windshields. The electronic
sensor that is on the
existing windshield in the car must be removed and re-mounted onto the
replacement windshield.

7-How is the rain sensor attached to the replacement windshield?
There are special re-attachment kits for the replacement industry, available
through your local Car dealer, which can be used to re-attach the electronic
rain sensor to the new windshield. The Cadillac kit consists of tape, cleaners
and primers for replacing the Cadillac module. The Mercedes / BMW kit
contains the tape and a new lens. Instructions for application are included in
all the kits.

7-Is it normal for HUD display to appear faded in bright light conditions?
Bright sunlight or high glare conditions can result in a dimmer display of the
Head's Up display. It is normal for a HUD to appear brighter at night in
darker conditions that during the day under full sun. It is not normal for the
HUD to completely disappear. If the display is fading when the car changes
momentum, such as when turning a corner or accelerating, then the problem
could be a system defect and it’s recommended that a dealer check out the
electronics. There is nothing in the windshield to cause the display to fade
or appear less intense.

7-What is a diversity antenna?
A diversity antenna combines the reception from several individual antennas
on the vehicle that makes it a very efficient antenna system. The definition
of diverse means different, therefore a diversity antenna in a backlite is one
that could Work with the mast (pillar) antenna mounted to the car. The two
different antennas work together to achieve superior AM/FM radio
reception. The 1998 Cadillac Seville has a diversity antenna system that
consists of an antenna in the windshield and antenna in the backlite that
work together.

7-What is a non-diversity antenna?
A non-diversity antenna system relies on only one antenna for radio wave
reception. Several examples of non-diversity antenna include 1) a mast
antenna mounted to the vehicle 2) an antenna printed on the backlite or 3) a
set of wires mounted into the windshield. A non-diversity antenna will not
be a combination.

7-What are the gild lines for across the top of the DW1313?
These are printed antenna lines on the windshield. Late model windshields
with antennas were produced by placing a thin wire in the windshield, which
was a costly and time-consuming process. Often, these wire antennas were
not efficient and eventually were not required for original equipment
requirements. The new process is very efficient and yields a superiorperforming
antenna. The antenna grid lines are printed on the surface of
glass with a conductive paste and then fired to the glass through the bending
process. Be careful when working around these types of antennas, a scratch
can break the line rendering the antenna inoperative.

7-Can a break in a HUD (Heads-Up-Display) windshield be repaired or
must it be replaced?
A break in the HUD windshield can be repaired like a normal non-HUD
windshield. If the repair area is in the HUD image area, a repair may
interfere with the image causing a double or distorted image. Therefore,
consideration is required to determine if the type and size of break is
repairable without HUD interference.

7-My customer wants to install an antenna on his vehicle, but was told not
to put it on passivated glass. What is passivated glass and why won't it
work with an antenna?
Passivated glass refers to chemically coated glass. Many automotive glass
parts are coated to achieve either the solar control characteristics or the
privacy features. The coating can usually be detected by the reflective,
mirror-like appearance. Sometimes these coatings will also have a color
associated with them and can make the glass look blue, pink or amber. The
solar coatings are used to filter out the sun's ultraviolet and infrared
wavelengths while the privacy coatings filter out visible light wavelengths.
The wavelengths that are filtered out by coated glass, include the wavelength
spectrums that CB radios, cellular phones, automated toll readers and radar
detectors operate on. Therefore, the chemically coated glass can interfere
with the operation of electronic devices that require a glass-mounted
antenna.

7-What type of glass is recommended for a glass-mounted antenna?
Glass that is referred to, as BATCH glass is compatible with glass mounted
antennas. Solar and privacy batch glass is not coated like the passivated
glass. Instead, the raw materials that give the glass its solar or privacy
characteristics are added at the time the glass is made. The raw materials are
melted right in with the sand and other components that glass are
constructed from. Once the glass has been made, it would not need any
other treatments prior to fabrication into automotive glass parts. Batch glass
is uniform throughout the thickness of the glass. Coated parts are surface
treated; the surface has different properties than the core of the glass.

7-Are there any special hints for re-attaching the rain sensor?
Make sure the glass is very clean prior to attaching the sensor. The
performance of the sensors depends on the optically clear grades of doublefaced
tape used for reattaching the units. These tapes also need to be clean
and free of bubbles when applied to the glass. Any impurities that may be
present will give a false signal to the rain sensor causing it to activate
unnecessarily.

8-What does the term "Auto-Cancel" refer to in the NAGS
catalog?******
The Auto Cancel notation means the electrical input to the heated backlite
design is automatically canceled after a specified time and/or temperature.
Most heated backlites made today are for automatic cancellation systems.
However, there are a few parts such as the Isuzu Trooper backlites where a
different glass heated design is required for the automatic vs. the manual
systems. For example, FB4815 is for an automatic cancellation heated grid
system whereas FB4816 is for a manual cancellation heated grid system.
8-What is the difference between a heavy-duty heated backglass and a
standard heated backglass?
The heavy-duty back glass is rated for higher amperage. The Heavy-Duty
(HD) designation is predominately used on foreign cars such as Honda and
Toyota vehicles. Normal domestic vehicles were rated for 22 amps whereas
heated backlites in Asian vehicles were generally rated for 11 amps.
Amperage relates to speed of performance. The higher the amperage, the
faster the backglass will heat and clear the frost from the glass. To
accommodate the US market, many foreign car manufacturers developed the
HD back glasses to offer compatible defrosting performance in the US. The
heavy-duty backglass are an upgrade, but it does not interchange with the
standard design.

8-What is the difference between DB8727 and DB8958?
These parts have different electrical terminal connectors for the heated grid.
These two parts are NOT interchangeable. The DB8727 has blade type
terminals and fits both the 1997 and 1995 Lincoln Town Car models. The
DB8958 has a box type electrical terminal and fits only the 1996 model year
Lincoln Town Car.