Glossary of Envelope Terms



Back Gum: Adhesive that cannot be remoistened. Used as a permanent seal for envelope seams.

Latex: Made from rubber-based material for self-seal envelopes. Latex is applied to the seal flap and the back of the envelope and sticks only to itself.

Pressure Sensitive: Applied to the seal flap and covered by release paper: self-sealing.

Remoistenable: Adhesive activated by water or solvent. Applied to the seal flap of envelopes.

Reusable: Latex adhesive designed to form a lighter bond for multiple sealing and resealing.

Strip-and-seal: See Adhesive, pressure sensitive.

Anilox Roller:  A hard cylinder coated by an industrial ceramic. The surface contains millions of very fine dimples, known as cells. A thick layer of  viscous ink is deposited on the roll and a measured amount of ink remains in the cells. The roll then rotates to contact the flexographic printing plate and the ink from the cells transfers to the printed material.



Bang-tail:  A style of envelope with a perforated coupon attached to the body of a return envelope. This portion must be torn off before the envelope is sealed. Used for remittance envelopes, order envelopes and other direct response devices.

Bar-Code:  See POSTNET.

Baronial:  A type of envelope recognized by large pointed flap.

Basis Weight:  See Substance Weight.

Blank:  A die-cut sheet of paper before it is folded into an envelope.

Bleed:  An image that extends beyond the edge of the page or envelope.

Blind Emboss:  A raised design stamped into paper without foil or ink, must be done before the envelope is folded to prevent the design from debossing onto the back of the envelope.

Bond:  A grade of writing or printing papers, often used for letterheads and matching envelopes. Characterized by strength, rigidity, relatively low opacity.

Booklet:  A large open side envelope used for catalogs, annual reports or brochures.

Brightness:  The light reflecting property of a paper. The more light it reflects, the higher its brightness. A bright sheet offers the best print quality and appearance.

Bulk:  Thickness of a sheet of paper in relation to its weight. A high bulk paper lacks compactness; a low bulk paper is compact, with less air space between its fibers. High Bulk papers offer a heavier feel to the touch, but a lower mailing weight.

Business Reply Envelopes (BRE):  Specially printed envelopes that may be mailed without prepayment of postage. The postage and fees are collected from the permit holder when the mail is delivered back to the sender. Also see FIM and/or PostNet.


Caliper:  The thickness of a sheet of paper, measured in units of 1/1000th inch (points or mils).

Catalog:  A general term for any large open end envelope.

CD Envelope:  A precisely sized envelope to mail, store and protect CDs. Can be made with or without windows or printing in a variety of substrates.

Center Seam:  An envelope style where the sides are folded and glued over each other, forming a seam that runs down the center of the envelope.

CI Press:  A high speed, high quality 4-color process of flexographic printing.

Closed Face:  An envelope without a window.

Commercial:  General term for the most common style of business envelopes. Open side, with or without windows.

Corner Card:  A term used to reference the return address and/or other identification of the sender usually located in the upper left hand corner of an envelope.

Courtesy Reply Envelope (CRE):  When a response is desired, such as with a bill or invoice payments, you pay only for the cost of envelopes. Your customer pays the postage, and no permit is required to send CRE mail. You can expedite returns by having pre-addressed and pre-barcoded envelopes.
Also see FIM and/or PostNet.


Deckle Edge:  Feathered edge on envelope flap, deliberately produced for decorative purposes.

Diagonal Seam:  Seam style frequently used in commercial open-side envelopes and announcement, invitation and baronial envelopes.

Die:  A precision tool used to cut out envelope blanks, windows or other shapes.

Double Side Seam:  (DSS): Type of seam configuration on open-side envelopes where seams tuck beneath back panel.

Double Outside Side Seam:  (DOSS): Seam configuration on open-side envelopes where seams are glued on top of back panel.

Drive-Up:  (Also called Teller-Helper envelope.) Used frequently by financial institutions to return cash to customers at counters and drive-up windows.


Embossed Finish:  A raised pattern applied to paper.

Expansion Envelope:  Envelope with a gusset or box bottom and sides, allowing it to expand for bulky mailings.

Eyelet:  Small hole in a tag or envelope to receive a string or clasp. May be plain or reinforced with a metal ring, paper or cloth backing.


Face:  The side of the envelope without seams.

FIM:  (Facing Identification Mark) A pattern of vertical bars printed in the upper right portion of the envelope. Used to identify BRE (has 6 vertical bars) and CRE (has 5 vertical bars) envelopes. These marks are used by the Post Office for automated facing and canceling equipment.

Finish:  The surface properties of a paper, including smoothness or textured, coated or uncoated, soft or hard. Different finishes offer different printing characteristics.

Flaps Extended:  A term used to describe the packing of envelopes with seal flap in an unfolded position.

Flexography (Flexo):  Economical form of printing that utilizes a photopolymer relief plate, essentially a modern version of letterpress method, using water-based inks. (see Printing)

Full View:  A Full View envelope has an extra large window designed to give maximum exposure to the contents. Especially valuable for attracting attention and enhancing response to direct mail advertising.


Grain:  Direction in which most of the fibers lie in a finished sheet of paper. Paper folds more easily with the grain. It offers greater resistance to being torn across the grain, and demonstrates greater tensile strength in the direction of the grain.


Inside Tint:  A printed design on the inside of the envelope used for added opacity and/ or security. Available in stock or custom designs. See page 15 for available tints.

Interoffice Envelope:  An open-end envelope designed for multiple-use routing of internal communications. Available with a variety of closures including clasp, string-and-button, and tamper evident peerless tact.


Kraft:  Paper grade made from unbleached, bleached or colored wood pulp by the sulfate process. Kraft papers have a coarser finish than woves and are noted for their strength.


Laid:  Type of finish, characterized by a closely “lined appearance”. -opened before packing. Eliminates “handflapping”.


Offset Paper:  General description of any paper primarily suited for offset printing. Can be coated or uncoated. Characterized by strength, dimensional stability, lack of curl and freedom from foreign surface material. Finish can be vellum or smooth.

Opacity:  Paper property that measures the degree to which paper stops light from passing through. Inside tints can be used to compensate for low-opacity papers.

Open-End:  Style of envelope in which the opening is on the shorter side. See Catalog Page 7.

Open-Side:  Style of envelope in which the opening is on the longer side. See Booklet Page 6.


Patch Material:  Refers to the material used to cover envelope windows. Can be translucent or clear. An envelope with a window but containing no patch material is referred to as an “open window”..

POSTNET:  (POSTal Numeric Encoding Technique) This is the barcode used to encode ZIP Code information letter mail for rapid and reliable sorting by barcode sorters (BCS’s). To receive automation discounts, letter-size mail must be 100-percent delivery point bar coded and meet addressing, readability, and other requirements for processing on automated equipment. Used on BRE and CRE mail.

Printing:  The choice of a printing process depends upon several factors. Some of which include the quantity, complexity and characteristics of the artwork, number of ink colors, as well as paper stock and the level of desired quality of finished product.

Flexography:  (Also called Flexo printing) A form of rotary letterpress using flexible rubber or photopolymer plates. Most common type of envelope printing, fast drying process, suitable for screens with 65-105 lines. Printed in line at the same time envelope is converted. Simplified art generally preferred. Usually, this method is most cost effective for larger quantities.

Enhanced Flexo:  Tighter registration, higher line screen, better quality than conventional Flexo and less expensive than lithography.

Jet:  Prints converted envelopes; equipment varies from 1 to 4 colors, 1 or 2-sided. Fast turn times, good quality, and medium pricing.

Lithography:  (Also know as FLAT SHEET LITHO or OFFSET PRINTING) Offers highest degree of precision, clarity and quality, uses screens of 133 lines or more.


Self-Seal Latex:  See Adhesives, Resealable.

Shelf Life:  The length of time after manufacturing that a product will remain in a saleable or acceptable condition.

Split Seal Gum:  Gum pattern on seal flap when envelopes are to be used on automatic inserting equipment. Gum is broken where flap covers envelope at seams; prevents flap from sticking to the back panel during storage in humid climates.

String-and-Button:  Mechanical closure with a string attached to the flap and a button on the body of the envelope.

Substance Weight:  (Also called Basis Weight) Weight, measured in pounds, of a ream (500 sheets) of paper in its basic size. Different grades of paper are sold in different basic sizes. Therefore, basis weights of different grades of paper can not be compared directly; a 24# white wove (WW) is comparable to a 60# offset, NOT a 24# offset.

Standard Substance Weights-Wove:
  • 16 lb. Used for overseas air mail envelopes.
  • 20 lb. Used for commercial envelopes where strength & opacity is not a factor.
  • 24 lb. Workhorse of envelope papers-used for most open-side official and commercial envelopes.
  • 28 lb. Used for most open-end and catalog envelopes and larger size commercial envelopes.
  • 32 lb. Used for heavy duty envelopes and clasp envelopes.
  • 40 lb. Used for large envelopes, heavy duty envelopes or envelopes used for frequent re-use.


Text:  Type of high quality paper, manufactured in white or colors from bleached chemical wood pulp and/or cotton fibers. Manufactured in a wide variety of finishes, including antique, vellum, smooth, felt-marked and embossed. Often has matching cover stock. In envelopes, most often used for annual reports, brochures or mailings where an envelope that matches or complements the enclosure is desired.

Thumb Cut:  Found on envelopes manufactured without flaps, such as filing and film storage. Can be cut on one side or double thumb cut, for easier extraction of contents.

Top:  When referring to the envelope specifications, the dimension of the envelope with the opening, even if it is on the

Tyvek®:  Spun bonded olefin product manufactured by DuPont. Offers maximum protection and durability at a very light weight. Tyvek® is unaffected by moisture and inert to most chemicals. Acid, lint and sulfide free.


Window:  A cut-out in the body of the envelope positioned to show mailing address, return address and/or special messages. Eliminates the duplication of efforts and the potential for error in addressing envelopes. Usually covered with a transparent window patch material. Can be left open with no patch, except in Canada.

Window Position:  Location of the window on the envelope, as measured from the left and bottom edges of the envelope. Window edge should be no closer than 3/8” from the side (to allow space for gluing window material) and 5/8” from the bottom (to correspond to current postal recommendations) of a standard commercial envelope. Other sizes and styles vary. Postal recommendations and regulations are subject to change.

Wove:  Paper having uniform surface and no discernible marks. Soft, smooth finish. Most widely used envelope paper. Lower in opacity, brightness and bulk. Available in white or colors.

Note: Envelope and window dimensions are always indicated with the height dimension listed first and the width dimension listed second.