june2023 - 16

1. Decide if the damaged area
requires replacement or repair
The decision to repair or replace generally comes
down to four elements:
ÜRegulatory requirements
ÜDriver vision
ÜStructural integrity of the glass
ÜCost and downtime for the fleet
U.S. Department of Transportation regulations
state that a windshield cannot have damage in
what is essentially a driver's primary viewing
area. That said, there are a couple of exceptions:
when a crack isn't intersected by other cracks; and
when the damaged area is no closer than 3 inches
to any similarly damaged area and can be covered
by a 3/4-inch-diameter disc. However, it's important
for fleets to understand that some states have
more stringent regulations.
" Some states require a windshield to be replaced
any time damage is on the driver's side within that
primary viewing area, " said Thomas Patterson,
director of new product development and technical
training for Glass Doctor, a Neighborly
Company, which specializes in glass repair and
replacement services. " We as a company do not
condone doing a stone chip repair in that primary
viewing area. That's where we would simply
recommend replacement. "
What is the driver's primary viewing area?
Based on the Repair of Laminated Auto Glass
Standard (ROLAGS), it is 12 inches centered off
of the steering wheel and 12 inches wide in the
path of the wiper.
Glass Doctor also doesn't like to attempt repairs
in the vicinity of any windshield wiper heater grids
that might be on the vehicle. " That creates a hot
spot, which we never want to do, " Patterson added.
For windshield damage that is outside of those
sensitive areas, there are instances where chips
and cracks can be repaired, helping a fleet reduce
both downtime and repair cost. This is also true of
similar types of damage to back glass and vehicle
door windows.
" Now it comes down to the type and size of
the break, " Patterson said, adding that there are
a few key damage classifications a glass technician
needs to look for.
A " bullseye " looks like the glass was shot by
a BB gun, but there are no visible legs or cracks
protruding out.
" A good glass technician can repair this type of
damage up to an inch in diameter, " Patterson said.
» Inductor Glass Blasters help technicians safely remove damaged windshields for replacement.
Induction Innovations
A " star break " does have three or four cracks
emanating from the point of impact. " As big as
you can safely go is around 2 inches, " Patterson
said. " Anything beyond that starts affecting the
integrity of the glass. "
A " combination break " is another form of
damage. This is essentially a star break on top of
a bullseye. " Again, anything 2 inches or smaller
can usually be repaired without much problem, "
Patterson said.
According to Patterson, one of the biggest
misconceptions is that a stone chip repair is an
aesthetic repair. In reality, the purpose of the
repair is to maintain the structural integrity of
the glass.
" When the repair is completed, it might not
look any different, and sometimes it might look
a thousand times better and almost disappear, "
Patterson pointed out.
2a. Make the repair
To properly perform a stone chip repair, there
are different types of tools and resins available.
Regardless of which specific products are utilized,
the process should always follow a proven blueprint.
" Many of today's vehicles have aluminum and/
or really thin pieces of metal. Traditional tools
have a decent chance of damaging those types
of materials. You have to treat the replacement
differently than when working with steel. "
Thomas Patterson, director of new product development
and technical training for Glass Doctor
" The first thing you want to do is create a
vacuum to extract any air or moisture out of the
break (using a specialized tool that works like a
syringe plunger), " Patterson said. Trapped air or
moisture is the dark color you can see in a break.
Once that air or moisture is vacuumed out, it's
time to introduce a liquid resin that bonds the
glass back together.
" Once the resin is suspended in that vacuum and
you open the chamber up, the vacuum pulls the
resin into the break to fill the void, " Patterson said.
Introducing the bonding resin is a relatively
straightforward process, but sometimes the technician
needs a little assistance. For example, the
tiny cracks in a star break may radiate out a bit
further than the vacuum can draw.
" Then the technician has to flex the glass to
open up the break, " Patterson explained.
Glass Doctor technicians use a steel probe to
push down on the center of the crack. That opens
up the inside of the break so the resin can flow in
from underneath and fill the crack all the way to
the end of the fingers.
Once the technician feels good with the repair,
the UV curing process can begin. Each resin is
matched with a specific range of the light spectrum
for curing.
" The technician puts on their UV lamp to cure
the resin, which essentially freezes everything in
place, " Patterson said. The curing process generally
takes just a few minutes.
" Then the technician is left with the pit where
the glass was removed from the break, " Patterson
continued. " Our technicians use a pit filler, which
is a more viscous and dense resin, to fill that pit.
They apply that resin and put a piece of polyvinyl
on top to hold it in place, and then cure it with
their UV light. Once that's cured, they just remove
the polyvinyl piece, scrape the filler down so it's
flush with the glass, and buff it until it's shiny like
the rest of the glass. "
16 Fleet Maintenance | June 2023

june2023

Table of Contents for the Digital Edition of june2023