Glossary of Envelope Terms

It is easy to be confused by the specific terminology, which is why we have devised a glossary of terms for you. The following list summarises many of the terms and definitions which we use.

BANKER: Diamond shape or V-flap opening on the long edge. They are also known as Invitation or Greeting Card envelopes.

BANGTAIL: A special type of wallet incorporating a perforated coupon attached to the envelope that can be detached for use as a reply form. They are typically used for donation/Gift Aid or remittance envelopes.

BASKETWEAVE: Manilla Paper with a weave effect finish, traditionally used for heavy weight manilla papers typically in 115gsm.

BESPOKE: Envelopes made to the customer’s unique specifications – not from stock.

BIODEGRADABLE/RECYCLABLE: These envelopes can be recycled and will biodegrade. As a result, they do not need to be used for landfill.

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

BLANK FED: Envelopes manufactured from flat sheets, punched out and made up.

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. Unless the design is on the flap, this process must be done before the envelope is folded to prevent the design from debossing onto the back of the envelope.

BOARD BACK: Often a pocket, constructed with a cardboard back (approximately 1000 microns) and paper front (typically 120gsm).

BOND: An uncoated 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.

BRE (BUSINESS REPLY ENVELOPE): These are envelopes with a pre-printed address that are enclosed in an outgoing mailing for the recipient to enclose a reply or remittance. Common UK sizes are: undersize DL (102x216mm), C6 (114 x 162mm). or undersized C5 (155x220mm).

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 is thicker and has more air space between its fibres. High bulk papers offer a heavier feel to the touch, but a lower relative mailing weight.

CARD ENVELOPE: An envelope made from card, for instance our Whitney Collection. Sometimes this will refer to an envelope that you would send a greetings card in. If this is the case,refer to our Brocken Collection for more information.

CALIPER: The thickness of a sheet of paper, measured in units of 1/1000th mm (micron)

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

CENTRE SEAM: An envelope style where the sides are folded and glued over each other, forming a seam that runs down the centre of the reverse of the envelope.

COLOUR WASH: Where a solid colour is printed bleeding off all sides of the envelope or shee. It can also be applied to an opaque.

COMMERCIAL: General term for the most common style of business envelopes that are hand fulfilled. They are normally self-seal or peel & seal.

DEADLOCK: Our derivative of the peel & seal adhesive that is significantly stronger than standard peel & seal. It also has a much longer shelf life of 5 years. Mainly available on the premium ranges such as PUR120.

DECKLE EDGE: Where paper has an untrimmed appearance to simulate the edge of handmade paper.

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

DRILLED HOLES: Holes drilled normally in internal mail transit pockets used to check for inserts.

EMBOSSED FINISH: A raised pattern applied to paper.

ENDURO: Tear resistant material made from a tri-laminate of paper/polythene/paper. It is fully over-printable and is a suitable alternative to Tyvek.

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 front side of the envelope without seams.

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

FLEXO: Printing technique using flexible rubber or photopolymer plates carried out during manufacture. This is normally used for the opaque of the envelope but also utilised on the outside for large quantities, however the process is not up to the quality of litho printing. Not suitable for doing fine text, linework or tints.

FSC (FORESTRY STEWARDSHIP COUNCIL): This is a chain of custody (COC) accreditation that provides full traceability of paper back to its certified forestry source. Peak Envelopes has undergone the rigorous process in order to supply envelopes in accordance with the certification.

FULL-FACE WINDOW: These have an extra-large window designed to give maximum exposure to the contents. Especially valuable for attracting attention and enhancing response to direct mail advertising.

GLASSINE: A paper-based material used for windows and some wage and photographic pockets. Very similar to tracing paper.

GSM (GRAMS PER SQUARE METRE, ALSO REFERRED TO AS GRAMMAGE): This is the weight of the paper and is measured in g/m2.

GUMMED:Refers to the envelope sealing method that requires moistening to seal.

GUSSET: These are normally pocket envelopes with expandable sides. They can have either a block bottom or V-bottom. All of our stock is V-bottom as it is more suitable for over-printing, but we can provide block bottom gussets if you prefer.

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

INVITATION ENVELOPES: See definition under banker

INSIDE SIDE SEAM: Envelopes where seams are glued beneath the back panel.

INTERNAL MAIL ENVELOPE: An open-end envelope designed for multiple-use routing of internal communications. Available with a variety of closures including clasp, string-and-washer, and tamper evident.

KRAFT: Paper grade made from unbleached, bleached or coloured 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” that emulates the coarse mesh of the original paper manufacturing machines.

LASER WINDOW FILM: This window film is double the thickness of normal film enabling it to go through laser and digital printers without melting in the machine. It measures 40-50 microns as opposed to standard 22 microns.

LITHOGRAPHY: (Also known as OFFSET PRINTING) This is the most common printing process that uses the immiscibility of oil-based ink and water to produce high quality print.

MACHINABLE: Envelopes suitable for use on an automatic inserting/mailing machine.

MAILING WALLET: A type of wallet suitable for use on an automatic inserting/mailing machine.

MATT COATED: Envelopes made from a coated paper that does not absorb ink in the way that an uncoated paper does and therefore produces a more vibrant job. As the ink cannot dry by absorption it has to be printed using UV drying technology.

MICRON (µ): Describes the thickness of paper in 1/1000mm.

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.

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: A printed design on the inside of the envelope used for added opacity and/ or security. Custom designs can usually be printed where required on bespoke jobs.

OUTSIDE SIDE SEAM: Envelopes where seams are glued on top of back panel.

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”.

PANTONE MATCHING SYSTEM: Also referred to as PMS colour, this is a colour system for reproducing consistent solid colours across different jobs and media. Each colour is specified by a number and mixed from a set of base colours.

PAS 2020: A responsible mail endorsement which is run by Royal Mail, who offer cheaper postal rates for environmentally sound mailings. Our Tryfan Collection meets the necessary criteria.

PDF (PORTABLE DOCUMENT FORMAT): The typical method of supplying artwork via email.

PEFC (PROGRAM FOR THE ENDORSEMENT OF FOREST CERTIFICATION SCHEMES): This endorsement provides full product traceability. Peak Envelopes has undergone the rigorous certification process in order to provide envelopes compliant with this accreditation.

PERFECTING: Litho printing on both sides of a sheet or envelope simultaneously.

PIP (PRICING IN PROPORTION): This is how Royal Mail now charge for posting of mail, based on the size and weight of the envelope.

POCKET: Envelopes with the opening on the short side, constructed with one side and one bottom seam.

PPI (POSTAGE PAID IMPRESSION): A pre-printed alternative to stamps and franking impressions for the UK and international mailings. It is a cost-effective solution for bulk mailing of homogenous mail that need to be posted out regularly.

RECYCLED: Envelopes made from post-consumer waste. See our Tryfan range, which is constructed using 100% recycled paper. If you are looking for manilla envelopes then the Bowfell Collection is right for you.

SELF-SEAL: The sealing method where the two flaps have a band of latex adhesive applied that are pressed together to form an instant bond.

SECURITY SLITS: Small slits in the flap of some self-seal envelopes designed as ‘tear points’ to provide a tamper evident measure.

SET-OFF: This is where the print on one envelope marks on another. UV driers will avoid this ensuring the envelope is dry when going onto the exit table.

SHELF LIFE: The useable life of an envelope. This term is generally used in relation to the self-seal and peel & seal envelopes.

SHOULDER: Top of the side-seams of a wallet. They can be a critical design aspect for inserting machines.

SIDE SEAMS: The seams at the sides of a mailing wallet. These can be outside or inside to suit individual mailing machine requirements.

STRING-AND-WASHER: Mechanical closure for repeated use with a string attached to the flap and a washer on the body of the envelope. The envelopes is sealed by winding the string around the washer

THROAT: The gap between the score line and back flap of a wallet. This can be a critical design aspect for inserting machines.

THUMB CUT: Shape cut from a topless pocket or wallet, normally in the shape of a semi-circle to aid the easy removal of the contents

TOPLESS: An envelope without a flap.

TOP: When referring to the envelope specifications, the dimension of the envelope with the opening.

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. This unusual material is fully printable.

UV DRYING INK: This is ink that is cured (dried) immediately by passing under a powerful UV lamp that is fitted to the exit of the envelope press and enables substrates, such as matt coated envelopes, to be printed without risk of set-off.

WALLET: An envelope with the opening on the long edge.

W & D 102: Reel-fed machine specifically used for producing gummed wallet envelopes up to an oversize C5.

W & D 249: Envelope machine used specifically for the production of larger format pocket envelopes, particularly C4 size.

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. They are usually rectangular with rounded corners but we can make bespoke envelopes with unusual shaped or multiple windows.

WINDOW POSITION: Location of the window on the envelope, as measured from the left and bottom edges of the envelope. Other sizes and styles vary.
Note:Envelope and window dimensions are always indicated with the height dimension listed first and the width dimension listed second.

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 colours.