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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 invitation envelopes.


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.

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.


Business Reply Envelope – normally an undersize DL (105x216mm or 102x216mm) also an undersize C5 (155x220mm). They are both now available from Blake and are gaining popularity.

Colour Wash

Printing technique used to give a tinted or coloured effect, often relates to internal opaque’s.

Corn Starch Window Film

Normal window films will not biodegrade, however using corn WINDOW FILM starch film it will biodegrade in 30 days. See our recycled envelope range.

Card Envelope

An envelope made from card, for instance our Purely Packaging Optima Card range. 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.


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, gives full traceability on raw materials such as pulp/paper.


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, refer to the gummed sealing section of this guide.


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.

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, looks similar to double sided tape adhesive.

Invitation Envelopes

A gummed envelope with a diamond flap usually used for greetings cards and invitations and sometimes referred to as a 'Banker'.

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.


Envelope for use on an inserting/mailing machine.

Mailing Wallet

See "Machinable".

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.


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

PAS 2020

An environmental standard for direct marketing that comprises a set of objectives, performance levels and indicators which set out how to create and manage an environmentally responsible direct mail campaign.


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


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


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


'Pricing in Proportion' is how Royal Mail now 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 Recycled range.

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.

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.

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.