
BEKAERT SPECIALTY FILMS,
LLC
4540
VIEWRIDGE AVENUE
SAN DIEGO, CA 92123
TELEPHONE: 858 576 0200
FACSIMILE: 858 576 8519
Graffitigard®
Protection from Glass Etching
Background:
A new method employed by graffiti vandals or “taggers”
is the use of glass etching compounds. These over the counter items
usually contain hydrofluoric, ammonium bifluoride and/or sulfuric
acids. These etching compounds can be mixed with shoe polish and
applied to windows where they will react with the glass within minutes.
The use of polyester film as a sacrificial barrier has been found
to be very useful in preventing damage to windows by physical and
chemical attack.
Test
Matrix: The 4 mil and 7 mil Graffitigard films (our thinnest
& thickest caliper) were tested for their protective capabilities
against readily available glass etching materials. Armour Etch®
glass etching cream and Etch Bath® glass dipping solution where
applied to 4 and 7 mil Graffitigard on ordinary 3mm annealed clear
float glass. The test panels were placed in a horizontal position
(worse case) and the etch compounds were left in contact with the
film for 24, 48 and 72 hours. The results from the exposures are
listed in Table 1.
Table
1
|
Film |
24 Hour |
48 Hour |
72 Hour |
|
Bare Glass |
Severe (5 minutes) |
N/A |
N/A |
|
4 mil Graffitigard
Etch Cream |
No Damage |
No Damage |
Slight glass marring |
|
4 mil Graffitigard
Etch Solution |
No Damage |
No Damage |
No Damage |
|
7 mil Graffitigard Etch Cream |
No Damage |
No Damage |
No Damage |
|
7 mil Graffitigard Etch Solution |
No Damage |
No Damage |
No Damage |
Conclusion:
Neither the Etch Cream, nor the Etch Bath, caused glass damage during
the extended test duration with the 7 mil Graffitigard. The Etch
Cream caused a very slight “haze” on the glass surface
with the 4 mil Graffitigard but only after 72 hours. The latter
result would not be expected in a realistic window configuration
for the reasons enumerated below.
The Etch
Cream was applied as a very thick coating. Therefore, the acid did
not completely dry-out during the entire test duration. In actual
use, the coating is assumed to be somewhat thinner, thus less likely
to cause damage. In a real-world scenario, the glass would more
than likely be cleaned within 48 hours, probably quicker if not
a weekend. Additionally, the experiment was carried out in a horizontal
orientation. More commonly, windows and glazing is vertical thus
allowing for run-off. Furthermore, the effect of exterior environmental
factors, solar heat, wind, etc… would cause these etchants
to dissipate faster; decreasing the actual duration the etchant
is in contact with the glass. Worth noting, the Etch Bath material
is extremely low in viscosity and does not wet out the film’s
surface well. The liquid etch would run off vertically installed
glass rather quickly.
*Armour Etch® and Etch Bath®
are registered trademarks of Armour Products.
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