Window Envelopes - Pitney Bowes DocuMatch Integrated Mail System Reference Manual

4 • Envelopes

Window Envelopes

Window envelopes come in different types and raise different
issues. The types used are open-face, glassine, DWF (Dow
™
Window Film
An envelope may have a window or be open-face (without a
patch). A patch is a transparent covering that is placed over
the window from the inside. Three different patch materials
are available for window envelopes.
Glassine
DWF
Trycite
4-6
™
) and Trycite .
This patch material is the most opaque and has
rarely been used over the past 10 years. When
the glassine window (a paper product) is glued
to the envelope, both surfaces become wet.
They do not dry at the same rate. This results in
wrinkling and puckering of the patch. Since
glassine is a paper product, it is recyclable.
Dow Window Film (DWF) is by far the most
popular window patch. It will allow for scanning
readability while providing a measure of
security. By security, we mean if someone tries
to examine the contents of the envelope
through the window, the patch material will
cloud their vision. Readability is excellent only
when material is held against the patch
material. DWF is a petroleum, not paper-based
product, and does not wrinkle or pucker during
the drying process. Because it is petroleum-
based, it is not recyclable like paper. DWF is
sometimes referred to as "Poly-Klear."
This type of patch material is usually on
expensive, high grade envelopes. Readability
by post office scanning equipment is poor due
to the reflectiveness or glare of this patch
material. Trycite is also called cellophane or
"Krystal-Klear."
DocuMatch ™ Mail Materials Reference Guide