It’s all about performance.
Solar Automotive Window Films: Tech bulletin
Dot Matrix
Dot Matrix, also known as “Frit”, is the printed border
around the perimeter of auto glass. This border is a
black enamel coating that is baked onto the glass during
processing. This is sometimes done with a clean line
approximately two inches from edge but usually with a
pattern of dots that fade to smaller pattern as you enter
viewing area of window. The purpose of this material is to
protect, obstruct view, and promote urethane adhesion to
car body. In the past, windows were installed using gaskets
where the glass simply rested in a channel. Windshields,
rear glass, and some side
windows on a vehicle will have
some type of pattern of frit
depending on their installation.
The addition of this border
allows the urethane to make
a stronger bond with the car
body while its color hides the
urethane and also protecting
it from the suns harmful UV
rays. You may also notice these
patterns in areas between the
windshield visors and top area
of rear glass used for shading.
This matrix takes many shapes
and forms depending on the
car. Nissan cars have an evenly
spaced pattern of dots along the top of the rear glass. A
majority of cars have the fade effect where the dots begin
very small and increase in thickness as it gets closer to the
edge. These are usually narrower and allow film to adhere
enough between dots as not to peel back. Very few cars,
like some Toyotas, use a solid border along the edge,
which for film installation is preferred. Ford cars since the
early 90’s seem to have the coarsest of dots and regardless
of prep, it always varies in adhesion. This is due to the fact
that the glass is manufactured at numerous plants and the
matrix surface varies based on the plant that manufactured
it. Although many film industry products claim to solve
the issue, not one to date, has proven to do so effectively.
Several issues play a part in this including thickness and
pattern of dot matrix. Even though adhesion is increased
with additional prep, the thickness and pattern of dots
can cause the film to “bridge” the area between the dots.
Although adhesion to the dots may be adequate, the
adhesive does not reach the glass area between the dots,
leaving air spaces or “whitening” between the dots.
www.solargard.co.uk
Saint-Gobain Performance Plastics
Unit 13, Ball Mill Top Business Park
Grimley, Worcestershire WR2 6LS
United Kingdom
Tel: +44 (0) 1905 640 400
PDF0250SG13INT 03/12
© Copyright 2012, Saint-Gobain Performance Plastics Corporation and/or its affiliates
All Rights Reserved • www.solargard.com
Please recycle
This dot matrix has become a major obstacle for applying
window film to cars. The challenge is when the film lays
across this band of dots, the thickness of the dots prevent
the film from reaching the glass therefore leaving an
inconsistent white appearance from the outside that leaves
many end consumers unhappy and installers frustrated. It
can also prevent edge adhesion causing film to curl away
from glass. Many actions have been taken to promote
better adhesion to the matrix such as sanding of the matrix
area with sand paper or steel wool. Also many installers
have attempted to use an
adhesive promoter on these
areas as well. Some dealers will
use a glue stick or similar type
of adhesive to fill the valleys
between the dots so the film
blankets the entire area leaving
glue stick material underneath.
This practice has not been
tested for long term effect on
film or sustained appearance.
A suggested combination of
treatments will help arrive at
the best result. This area should
be prepped considerably more
than the viewing area of the
window. To avoid scratching the
glass, a strong non-abrasive pad should be used instead
of sandpaper or steel wool. Scrubbing vigorously, one will
notice a white residue washing off. This residue should be
completely removed then rinsed. In addition, a low grit
sandpaper can be used to assist in reducing the height of
the dots. Use caution when doing this as any contact with
the glass viewing area can result in visible scratches. Upon
film installation, the entire window should be squeegeed,
including the matrix area. The entire window should then
be dried along the edges. By first removing excess soap
and water solution, you are preparing surface for the best
possible adhesion. Film in the matrix area should then be
pulled back away from glass and sprayed with an adhesive
promoter (Part# ST0813) and squeegeed to the edge
firmly with a dry towel using several slow passes to soak
up any residual water. This method of preparation should
provide the best results for adhesion to the dot matrix areas.