Technical / FAQs

Glossary of Terms


Action Device: Intended to generate interaction with the recipient and make them more likely to open the envelope.


Back Gum: Also known as Seam Gum. This is an adhesive that cannot be remoistened. It is used to seal the seams of the envelope to form the envelope pocket and provide a permanent bond at the envelope seams

Seal Gum: seals the envelope when moistened.

Gummed (Re-moistenable): Adhesive activated by water or solvent. Applied to the seal flap of envelopes.

Latex (Press & Seal): Made from a 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.

Peel and Seal (Zip Stick): (Also called Pressure Sensitive Gum) Applied to the seal flap and covered by release paper; self-sealing.

Peerless Tac: A unique closure device designed for long life with repeated opening and closing.

Re-sealable: A latex adhesive designed to form a lighter bond, this is used for multiple sealing and resealing.

Adjustable Die Cut: Adjustable envelope die used to cut from pre-trimmed paper.

Announcement: Baronial envelopes have deep, pointed flaps and diagonal seams. A series enveopes have deep, square flaps with two side seams. Used with baronial cards, informal or special event mailings.

Artwork: A general term used to describe photography, negatives, drawings, paintings, hand lettering, etc., prepared to illustrate printed matter.

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Back-Gum: See Adhesives

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

Bankers Flap: A type of banker's envelope known for its deeper flap.

Bar-Code: A series of vertical bars used by the Postal Service to speed mail processing. Generated by the Post Office as mail passes through OCR scanners or pre-printed by the manufacturer. If not pre-printed, space must be available on the bottom right of the envelope for the bar code.

Baronial: Type of envelope recognized by a large pointed flap, usually open side with diagonal seams. Used most often for social correspondence, including announcements, greeting cards and invitations.

Basis Weight: See Substance Weight.

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

Bleed: In printing, an image that extends off the edge of the page or envelope. Envelopes with bleed generally must be printed before they are folded, since the fold line runs through the printed image.

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 Paper: 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 for catalogs, annual reports, brochures. This is a popular style because it can be used with automatic inserting machines. The term booklet can also be used to refer to commercial open side envelope with two side seams.

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 Packed: Packaging envelopes in a carton versus separate boxes within a carton.

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 Intelligent Mail® Barcode (IMb)

Business Reply Mail (BRM): Specially printed cards, envelopes and cartons mailed by the end user without paying postage / postage is billed to the permit holder. Also see FIM and/or Intelligent Mail® Barcode (IMb)

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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 / flap opening is on the short side, usually with a center seam.

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.

Cello: Abbreviation for cellophane which is a window material that is very clear. Due to the expense, cello is not used as much as it once was. It can be too reflective, causing errors in OCR reading.

Center Seam: An envelope style where the sides are folded and glued over each other, forming a permanent seam that runs down the center of the envelope. This style is most commonly used on coin and catalog envelopes.

Clasp: A metal fastener sometimes used with re-moistenable gum on booklet and catalog envelopes, allows for repeated opening and closing of the envelope.

Closed Face: An envelope without a window.

Closure: General term used for the means of closing and securing an envelope. May be an adhesive, a clasp or other mechanical closure.

Commercial: General term for the most common style of business envelopes. Usually with diagonal or inside side seam, this envelope is an open side, a can be made 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.

Coupon: The tear-off portion of a bang-tail 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 preaddressed and pre-barcoded envelopes. Also see FIM and/or Intelligent Mail® Barcode (IMb)

Credit Card Protector Sleeve: An open-end or open-side envelope perfectly sized to hold and protect credit cards, phone cards and hotel room keys. Available in paper or Tyvek®.

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Deckle Edge: Feathered edge on envelope flap, deliberately produced for decorative purposes. Formed especially on formal announcement or invitation envelopes.

Diagonal Seam: Seam style frequently used in commercial open side envelopes, invitation and baronial envelopes. Its name is derived from the seam running from the back corner of the envelope diagonally to the middle.

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

Double Inside Side Seam (DISS): 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.

Drilling: Precision-piercing stacks of envelopes to ensure the recipient removes all contents.

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

Dummy: See Mock Up

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Embossing: A process performed to stamp a raised image into the surface of paper, using engraved metal embossing dies, extreme pressure and heat. Embossing styles include blind, register embossed, and foil embossed.

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

Extension Flap / Tab: See Lip

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.

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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.

First Class Envelope: A catalog style (open-end) envelope printed with green “First Class” around the edges.

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

Flaps Folded: Flaps are folded down against the back of an envelope.

Flexography / Flexo: See Printing

F.O.B.: Stands for “Freight on Board” without charge for delivery to and placing on board a carrier at a specified point; the point at which the shipping charge is calculated.

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.

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Glassine: A smooth, dense semi-transparent paper. Sometimes used as window patch material.

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.

Gum: See Adhesives.

Gussets: Envelopes with expanding accordion pleats for extra capacity.

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Halftone: Picture with gradations of tone, formed by dots of varying sizes in one color.

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Imprinting: Printing on made-up envelopes.

Indicia: Mail piece imprints (upper right corner) that denote payment of postage.

Insert Size: As a rule of thumb, envelopes should be one half inch wider and one fourth inch higher than the largest piece to be inserted. Automatic inserting equipment may require more space.

Inserting Machine: Automatically inserts contents into envelopes.

Inside Side Seam: Seam construction on a Booklet envelope where the seam glues beneath the back panel.

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

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.

Intelligent Mail® Barcode (IMb): The Intelligent Mail barcode, formerly referred to as the 4-State Customer barcode, is a new Postal Service barcode used to sort and track letters and flats. The Postal Service is promoting use of the Intelligent Mail barcode because it expands the ability to track individual mailpieces and provides customers with greater visibility into the mailstream. The Intelligent Mail barcode combines the data of the existing POSTNET™ and the PLANET Code® barcodes, as well as other data, into a single barcode.

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Jet Printing: See Printing

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Kraft Paper: 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.

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Laid Paper: Type of finish, characterized by a closely “lined appearance”.

Latex: See Adhesives

Lip: A smaller flap parallel to an envelope's opening that is not sealed, scored or folded on some open-side envelopes, such as those used for filing.

Lithography / Litho: See Printing

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Machine Insertable: Envelopes configured for using on machines that automatically insert their contents.

Machine Readable: Envelopes with a barcode that’s read by a laser scanner or similar device.

Manila: A semi-bleached chemical sulfate paper. Not as strong as Kraft, but with better printing qualities.

Mock-Up: A mock-up of a “to-be-printed” piece. A dummy serves as a reference for the client, printer, mailing house, or distributor.

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Nest-End: Term referring to packing of envelopes where they are nesting together with flaps extended. Flap is scored, closed and then re-opened before packing. Eliminates “handflapping”.

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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.

Offset Printing: Also known as web offset or lithography. Offers highest degree of precision, clarity, and quality. Uses screens of 133 lines or more, printed flat sheet, then folded. Can be solid PMS, in multiple colors and process printing.

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.

Opaque: The interior security wash or grey wall printed in an envelope that allows no light to show through.

Open-End: Style of envelope in which the opening is on the shorter side. This envelope usually has a center seam on the back or a single side seam.

Open-Side: Style of envelope in which the opening is on the longer side with either a diagonal or double side seam.

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

Patch Pocket: Paper or window film gummed to form a pocket behind a window.

Patching: Affixing material onto window envelopes.

Polystyrene: A thermoplastic material used for window patch.

POSTNET Barcode: (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) prior to January 28, 2013. After this date, the USPS eliminated the use of the POSTNET barcode for automation discounts, instead requiring the new Intelligent Mail® barcode (IMb) be used for automation discounts.

Presort: Mail pieces grouped by zip code or other USPS recommended separation to bypass certain postal operations.

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 the paper stock and the level of desired quality of the finished product.

Lithography: (Also known as FLAT SHEET LITHO or OFFSET PRINTING) Offers highest degree of precision, clarity and quality, uses screens of 133 lines or more. Artwork with full bleeds requires flat sheet lithography. Highest quality, top of price range.

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. The art is lower imagery art. Generally the most cost effective price for larger quantities.

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

Thermography: Printing process that produces raised lettering simulating engraving. Used in letterheads and matching envelopes, business cards or announcements.

Proxy: A booklet style envelope used to mail an annual report and a proxy statement. Contains a special pocket for the proxy.

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Ream: 500 sheets of paper.

Regular Envelope: A style of commercial envelope without a window.

Remittance Envelope: Have a large style flap that is approximately the same size and shape of the envelope itself. They have a large printing surface, with or without perforation for returning information. Donors can provide their information, include their financial support and return the envelope to the sender.

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Seal Gum: See Adhesives

Security Tint: See Inside Tint

Self-Seal Latex: See Adhesives

Shelf Life: How long a product can be stored under specified conditions and remain usable; normally 6-9 months for most envelopes.

Side Seam Inside: Single seam construction on open-end envelopes, where seam glues beneath back panel. Allows full printing on back of envelopes. Can be on left or right side. (LISS or RISS).

Side Seam Outside: Single side seam construction on open-end envelopes, where seam is glued on top of back panel. Can be right of left side. (ROSS, LOSS).

Size: The measurement in length and width of an envelope or window.

Special Window: Any non-standard window envelope. See our window envelopes for standard sizes/positions; we can custom-create a window in almost any position.

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 cannot 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 reuse.

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Teller-Helper: See Drive-Up.

Text Paper: 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 other prestige mailings where an envelope that matches or complements the enclosure is desired.

Thermography: See Printing

Throat: Space between the top of an envelope's back flap and its top flap crease line.

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.

Tint: See Inside Tint

Top: When referring to the envelope specifications, the dimension of the envelope with the opening, even if it is on the “side” relative to the address, corner card, etc.

Tuck Flap: Flap with no gum, used primarily on interoffice and other reusable envelopes.

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.

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Wallet Flap: An envelope with an extra large flap to provide a larger printing area and added protection.

Web: A roll of paper used in Web or rotary printing. Also, can be referred to the manufacturing of an envelope where die cutting and folding is done on one machine using a continuous roll of paper. Envelopes made on a web are usually made with side seams.

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. Customized windows can be created in the shape of product or logo. 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: 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.

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