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'A' series

The smallest series of the ISO system of standard paper sizes. The others are 'B' and 'C'. 'A' is most widely used for stationery sizes, such as A4, the usual European letter size. See paper sizes for more details.


The cut-out part of the face or back of an envelope designed to form the window, allowing part of the envelope contents to show through (usually the address), or an envelope with such an aperture but without any widow material.


A wallet envelope with one side flap and the corresponding half of the top flap left ungummed. Commonly used for gas and electricity bills.

'B' series

The largest series of the ISO system of standard paper sizes. The others are 'A' and 'C'. 'B' sizes are most widely used by the printing trade where a design requires bleed on an item to be finished to a smaller 'A' size. An A2 finished item with bleed may well be printed on a B2 sheet then trimmed to the finished size. See paper sizes for more details.


An envelope with the opening on the longer side with a diamond flap


An unfolded envelope

Board backed envelope

Where the face and flaps are made from paper and the back made from board. Used to protect the envelope contents.

Body size

The dimensions of an envelope when sealed.


This term refers to a Business Reply Envelope - an envelope showing a business reply licence number and postage rate symbol. Included to encourage response in direct mail campaigns, and by organisations such as the Inland Revenue. See also Freepost below.


This is a description of the thickness of a given sheet in proportion to its grammage

'C' series

The middle series of the ISO system of standard paper sizes. The others are 'B' and 'A'. 'C', along with some of the 'B' sizes, is used for producing envelopes. 'C' sizes are larger than 'A' so, for example, a C4 envelope will take an A4 insert without folding. See paper sizes for more details.

C4, C5, C6

Common envelope sizes derived from the 'C' series. For actual dimensions see envelope sizes.


This refers to a shallow triangular shape of flap on wallet envelopes. Not usually suitable for machine enclosing jobs.

Coated envelope

Envelopes made from a coated paper (paper coated with a fine china clay during its manufacture). Used for greater depth of colour reproduction in some four colour work.


A design of wallet made up with the side flaps outside the back flap. The position of the overlap of side and back flaps and the 'step' in thickness this creates may effect the design of the overprint.


The scored line along which the seam of the envelope is folded.


A starched based adhesive used in envelope manufacture.


A deep triangular flapped wallet often used for greetings cards, not suitable for machine enclosing.

DIN sizes

Deutsche Industrie Normen, the German standard that was the origin of the ISO paper sizing system (rarely used).


A common envelope size, the name of which refers back to the DIN (literally from DIN (Lang) - DL) origins of paper and envelope sizes. For actual dimensions see envelope sizes.


The box end labels, bands or any other printed material constituting part of the packaging which describes the envelopes contained.

Environmentally Friendly

This is a catch all term used in relation to paper and board products including envelopes. Most envelopes are made from grades of paper that contain a percentage of recycled material. There is no minimum requirement for recycled content (post-consumer or mill waste) in the UK to justify the term 'recycled'. See also TCF below.


A high-speed relief printing process using flexible plates and fast drying inks. Limited applications.


This is a service offered by Royal Mail which allows business users to offer postage free response to marketing campaigns. The responder doesn't need a stamp, only the correct Freepost address on the envelope. See also BRE above.


The Forest Stewardship Council enables you to buy forest products of all kinds with confidence that you are not contributing to global forest destruction. FSC certified forests are managed to ensure long term timber supplies while protecting the environment and the lives of forest-dependent peoples.

FTP - File Transfer Protocol

A communication method for transferring data between computers on the Internet. FTP servers store files that can be accessed from other computers. FTP provides security services so only authorised access is allowed.

Galley proof

A style of proof common in the use of letterpress, now largely obsolete.


A style of envelope requiring an origami style folding and inserting of a long straight-edged flap to close it.


A translucent glazed paper produced by heavy refining and calendering.

Grammage, g/m2, gsm

The weight in grammes of a sheet of a given paper one metre square. This is the characteristic most commonly used to indicate the relative quality of papers from the same stock. Between stocks, other characteristics should also be considered, such as opacity and bulk.


The 10mm that needs to be allowed on the leading edge in the design of some envelope overprinting.


Envelopes which allow for extra capacity by expanding accordion pleats.

Hand cutting and Hand folding

Process of cutting envelopes by guillotine or adjustable die (rather than by a programmed or conventional press) and the folding of them by hand. For low volume custom envelopes.

Inserting machine

A machine for automatically inserting enclosures in to envelopes. often referred to by the manufacturers name - a Phillipsberg, a Pitney Bowes etc


Inserting material between two surfaces (could be the back of one envelope and the face of the next) to prevent set-off following printing.


Integrated Services Digital Network - a new fast digital phone line that allows high volumes of data (such as graphics files comprising artwork) to be transferred up to five times faster than an ordinary phone line. Also the way in which larger corporate Internet users will connect to their service provider.


International Standards Organisation - the body which establishes standards such as the A, B and C series for paper sizes.

Jiffy bag

A padded envelope made from kraft. Essentially one envelope within another with the interspace filled with finely shredded newsprint.


A term used to describe the die or cutter used in the making of blanks.


A grade of material used in the manufacture of envelopes and card.


The material used in place of gum in 'self-seal' envelopes. Has a limited shelf life.


A relief printing process (the image is raised above the material printed on), now largely superseded by off-set lithography.


A high-speed planographic printing process making use of a chemically treated plate that accepts ink according to the design, but all other parts of the plate preferentially accept water.

Loose side flap

See Appellant

Moisture content

This is the ratio of the weight of water that can be driven off a sheet of paper at 105°ree;C to the total weight of the sheet before drying; expressed as a percentage. The moisture content of a given paper, or envelopes made from it, has relevance to the papers performance in various types of printing process, especially those that involve heat, i.e. laser printing.

Non-curling gum

A term once used to describe adhesive used on the envelope top flap with flat lying properties necessary for machine enclosing or inserting.


A reference to the non-transparency of a paper or the envelope made from it. The higher the opacity the less the contents of an envelope show through. Envelope blanks are frequently printed on what will be the inner of the finished envelope to improve the opacity.


The name for the interior security wash or greywall printed when an envelope is made.

Open end

Another name for a pocket envelope.

Open side

Another name for a banker or wallet envelope.

Panel back

An envelope where the back is a separate panel rather than part of the same sheet folded over. Usually found in very large sizes made by hand.

Patches and patching

The transparent window material and the process of fixing it over the aperture in the making of window envelopes.


The PEFC Council (Programme for the Endorsement of Forest Certification schemes) is an independent, non-profit, non-governmental organisation, founded in 1999 which promotes sustainably managed forests through independent third party certification. The PEFC provides an assurance mechanism to purchasers of wood and paper products that they are promoting the sustainable management of forests.

Pressure sensitive gumming

A self-seal adhesive flap activated by pressure, protected by a strip of siliconed paper to prevent premature bonding. Often found on board backed envelopes. Often referred to as 'peel and stick' or securseal/stripseal


The parts of the envelope which are sealed down during manufacture. The seam positions can have an impact on the design of overprinted envelopes.


The unwanted transference of a reversed image during printing, from the back of one envelope to the face of the preceding, due to inadequate drying. A significant problem with coated envelopes, usually avoided by printing flat sheets, or by using Surrey Envelopes' coated process.


The parts of the side flaps at the crease with the top flap.

Square sheet

A rectangular sheet of paper from which envelope blanks are cut.


A term now superseded by grammage.


Total Chlorine Free, this is the term applied to papers and boards made from material which has been bleached with a chlorine free process. See also environmentally friendly above.


The space between the top of the back flap and the top flap crease line.

Tissue lining

A piece of thin material lining the inner of an envelope; originally to improve opacity but now largely decorative and confined to personal stationery.


The practice of allowing a margin of ± 2mm in the manufacture of an envelope (including widow size and position).

Top flap

The flap normally left open for insertion of contents into the envelope.

Topless envelope

One without a top flap

Truncated flap

A diamond flap with the apex cut off to form a straight edge parallel to the top and bottom crease.

Uncoated envelopes

These are also known as cartridge, and represent the bulk of envelope production. See also coated envelopes.


Tinting out to nothing


An envelope with the opening on the long edge, also referred to as a banker.


The cut-out part of the face or back of an envelope covered with a transparent material, allowing part of the envelope contents to show through (usually, but not only, the address). The window material can be coloured for greater impact or a more integrated design. Click for here for details of our coloured window film.