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Like most industries, the envelope industry has its own technical terms or jargon. The following list summarises many of the terms and definitions used:


Diamond shape or V-flap opening on the long edge, also known as invitatiiew our banker envelopes here.


Special type of wallet incorporating a perforated flap. Extension from the throat e.g. Barclaycard envelope.


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


Envelopes made to customer specifications, not from stock.

Biodegradable / Recycleable

These envelopes can be recycled and will biodegrade, so do not need to be used for landfill. Take a look at our Purely Environmental range here for a wide range of options.

Blank Fed

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

Board Back

Generally a pocket made with a cardboard back & paper front. 120gsm paper and around 1000 micron board. View our Purely Packaging board back range here.


Business Reply Envelope – normally an undersize DL (105x216mm or 102x216mm) also an undersize C5 (155x220mm). They are both available from Blake within our Purely Everyday range here.

Colour Wash

Printing technique used to give a tinted or coloured effect, often relates to internal opaques.

Corn Starch Window Film

Normal window films will not biodegrade, however using corn window film starch film it will biodegrade in 30 days. These are available in our Purely Everyday recycled envelope range here.

Card Envelope

An envelope made from card, for instance our Purely Packaging Optima Card range here. Sometimes this will refer to an envelope that you would send a greetings card in, in this case this would refer to our Invitation envelopes.

Diamond Press Envelopes

A make of envelope printing press, good for larger sizes such as C3, board backs and gussets.

Drilled Holes

Holes drilled normally in internal mail transit pockets, used to check for inserts. For our internal mail envelopes, click here.


Printing technique carried out during manufacture or printing in-line, for large quantities not up to the quality of litho printing.


Stands for Forestry Stewardship Council, which gives full traceability on raw materials such as pulp/paper. For our FSC range, click here.


Paper based material used for window and some wage and photographic pockets.

GSM / Grammage

Determines the weight of the paper, measured in g/m2.


Refers to the envelope sealing method that requires moistening to seal. Learn more about envelope sealing types here.


Normally a pocket envelope with expandable sides. Can be block bottom or V- bottom. All our stock is V-bottom as it is suitable for over printing. Learn more about envelope styles here, or take a browse of our range of gusset envelopes here.

Halm Jet Press

A make of envelope printing press most commonly used in the industry. Available in 2 and 4 colour and more recently 5, with dryers that enable the envelope to be printed 4 colours on face and 1 colour on the flap (i.e. return address) in one pass, known as EM 5000.

Hot Melt

Is a form of Peel & Seal adhesive, a narrow band of adhesive with a heavier gram weight than normal gives a shelf life of 5 years and looks similar to double sided tape adhesive. Learn more about envelope sealing types here.

Invitation Envelopes

A gummed envelope with a diamond flap usually used for greetings cards and invitations and sometimes referred to as a 'Banker'. Click here to learn more about envelope styles, or view our invitation envelope range here.

Laser Window Films

This window film is double the thickness of normal film enabling it to go through laser/digital printers without melting in the machine. It measures 40-50microns as opposed to standard 22mm. Learn more about window films here.


Envelope for use on an inserting/mailing machine.

Mailing Wallet

See "Machinable", or click here to learn more about envelope styles.

Matt Coated

Envelopes made from coated paper designed for full colour overprint.


Describes the thickness of paper in 1000mm


Printed design or wash inside an envelope typically for security. Learn more about opaques here.


Reference for shades of print colours - each one has an individual number. Also referred to as PMS colour (Pantone Matching System).


Method of supplying artwork via email (Portable Document Format).


Programme for the endorsement of Forest Certification Schemes, which gives full product traceability.


Litho printing on both sides of an envelope at the same time.


'Pricing in Proportion' is how Royal Mail charge for posting of mail, based primarily on the size of the envelope. small letter, large letter, parcel.


Envelope with opening on the short side.


Postage Paid Impression e.g. 1st Class, Mailsort.


Envelopes made from post consumer waste, see our Purely Environmental recycled range here.

Reel Fed

Envelope manufactured from reels of paper, most cost effective of our envelopes.

Self Seal

Refers to sealing method where the two flaps are pressed together to form an instant bond. Learn more about envelope sealing types here.

Security Slits

Small slits in the flap of some self seal envelopes designed as 'tear points' for tamper proof security.

Shelf Life

Useable life of an envelope. Generally applied to Self Seal & Peel and Seal envelopes.


Top of the side flaps of a wallet. Can be a critical design aspect for inserting machines.


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 feed table.

Side Seams

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


Gap between the score line and the back flap of a wallet. Can be a critical design aspect for inserting machines.

Thumb Cut

Shape cut from a topless pocket or wallet, normally a semi circle.


Pocket or wallet without a flap.

UV Dryer

Fitted to the back of the envelope press, it enables substrates such as matt coated envelopes to be printed without risk of set-off.


Envelope with opening on the long edge. Learn more about envelope styles here.

W & D 212/214

The 'Rolls Royce' of envelope presses, more expensive than the other two mentioned, but better built and with heavier roller power which is ideal for solid blocks of printed colour. The 212 is two colour whilst the 214 is four colour.

W & D 102

Reel fed machine specifically used for producing gummed wallet envelopes up to oversize C5.

W & D 249

Envelope press specifically for the production of larger format pocket envelopes, particularly C4 size.