| Window Types | Closure Types
Envelopes are constructed in many different ways.
The envelope can vary in the type of paper, seams, closures, size and special
features used. All envelopes are manufactured as a sheet and then folded according
to the type of envelope being produced. Shown below are two standard envelope
constructions. The diagrams will give you a basic idea of how most envelopes
Bangtail - The extra flap on the back panel
of the envelope, which is detached at the perforation before the envelope
Center Seam - A glued seam that runs up the
middle on the back side of the envelope, from the bottom edge up to
Closure - The way in which an envelope is sealed
at the opening.
Commercial - The most commonly used envelope
style. It is an open side with diagonal seams. Available as a regular
or a window envelope.
Diagonal Seam - Seams
that run diagonally across the back of the envelope from the bottom
corner to the throat. Used mostly in commercial, announcement, invitation
and baronial envelopes.
Gusset - The expandable sides on an expansion
Inside Tint - Printing on the inside of the
envelope that protects against seeing the contents of the envelope.
Open End/Catalog - The opening of the envelope is on the shorter
side. An open end will generally have a center seam on the back.
Open Side/Booklet - The opening of the envelope
is on the long side. An open side generally has diagonal seams or double
Inside Seams - A side seam that is glued under
the back panel. Inside seams allow the entire back panel to be printed.
Outside Seam - A side seam that is glued on
top of the back panel, limiting the printable area on the back panel.
Regular Envelope - An envelope that does
not have a window cut out of it.
Seal Flap - The flap at the top of the envelope
that folds down over the throat to seal the opening of the envelope.
Side Seam - A glued seam that
runs parallel to the side fold, used to hold the envelope together.
Throat - The opening area on
an envelope that generally gets covered by the flap when the envelope
Thumb Cut - A half circle die cut out of
the opening edge, either through one side or both. It is used on envelopes
without flaps to make it easier to remove the content.
Top - The edge of the envelope where the
opening is, whether it is on the short or long edge.
Window - A die cut opening in the body of
the envelope, used to show a portion of the content of the envelope,
such as, an address or a special message.
A window is used on an envelope to allow a portion
of the envelope content to be visible. There are standard size windows for
different types of envelopes but most any size window can be added to any
type of envelope. It is best to see if there is a standard window envelope
that will fit your needs and then design your content to fit the window, this
will save the additional cost of a custom window envelope. Also, when ordering
a custom envelope, there may be a minimum order quantity required.
9 x 12 Catalog Envelope
with a Standard Window
#10 Window Envelope
with a Standard Window
#8 5/8 Double Window Envelope
with inside tint and two Standard Windows
Window Patch - Covering for the window opening.
Polyclear - Most popular, least expensive, and best for scanning
by postal service.
Glassine - Cloudier than polyclear, harder to achieve acceptable
postal scanning . Is completely recyclable.
Cellophane - Higher clarity than polyclear but more expensive.
Acceptable for postal scanning but is not recyclable.
Window Position - Location of the window from
the left edge and up from the bottom.
Size and Placement.
Note: The window envelope
does not have to have a patch covering the window. It can be
left as an open window.
There are several different closure types available.
Some of the standard envelopes are available with different types of closure.
Adding a closure to an envelope, that is not a standard closure for that envelope,
would require a custom order. Contact your supplier with any special requests
you may have.
Shown below are some of the common types of closures
Remoistenable Gum - Most commonly used adhesive.
It is applied to the seal flap and must be moistened to adhere the
flap to the envelope.
Split Seal Gum - The gum adhesive on the seal flap is broken where
the flap covers the envelope seams, preventing flaps from sticking
to the back panel when stored in humid conditions.
Latex Seal - A pressure sensitive adhesive
that only sticks to itself. A strip is applied to the seal flap and
the back panel. Envelopes are stored with flaps extended and will
not stick until the flap is folded down and the adhesive on the flap
and the back panel come in contact with each other.
Flip and Seal - Available on open side envelopes with side seams.
There are two flaps on the envelope, one in the standard position
with a latex seal and a second one folded down at the throat of the
back panel with the latex seal folded under. When the second flap
is folded up and the seal flap is folded down, the two latex seals
come in contact with each other and form the seal.
Peel & Seal - The seal flap has pressure sensitive adhesive
applied to it and there is a protective release paper covering the
adhesive. The release paper is removed and when the flap is folded
down and pressure is applied, the flap will adhere securely to the
Resealable - An adhesive designed to form a lighter bond so that
the envelope could be opened and closed multiple times without damaging
Clasp - A metal clasp is used in addition to a regular gummed
flap. The clasp adds security to the closure and also allows repeated
opening and closing of the envelope.
String and Button - A manual closure where a string and button
are attached to the flap and a button is attached to the body of the
envelope. The string is wrapped around the button on the body and
then the back up around the button on the flap to seal the envelope.
Used on inter-office and reusable envelopes where repeated opening
and closing of the envelope is necessary.
Tuck-in-Flaps - A type of closure that has
two tabs on the flap. When the flap is folded down, the tabs fit into
slots on the body of the envelope to form the seal. Tuck-in-Flaps
are used on board mailers and provide a secure closure without the
use of adhesive.
Tamper-Evident - A security closure, available on various Tyvek®
envelopes, that alerts the recipient if the envelope had been opened
before they received it.
Types - Tyvek® Tamper Evident.
Back to Top