Glossary of Terms

A guideline for easy reference to terms used in the envelope industry

Acid Free Paper
Paper with no acidity and a slight alkaline content. It is also used for microfiche jackets because of the sensitivity of film to acids. The manufacturing process uses no elemental chlorine.

Adjustable Die
An envelope die, which is made from four separate pieces of angled steel, held together with long threaded bolts. This design allows the corners to be moved in and out to create almost any size envelope from 150x114mm to 458x324mm. These dockets are usually pocket shape

Bang Tail
A one piece punched style envelope, with perforated additional back section.

With barcodes being vital in the modern retail market, Merpak offers you the facility of barcode printing and reading.

In offset Lithography, a rubber-surfaced blanket clamped around the cylinder, which transfers the image from plate to paper.

Paper punched to form the shape of the envelope.

Punched out blanks followed by printing and converting process.

a printed image which extends all the way to the edge of an envelope. OFTEN the direction of a bleed is also indicated, for example, “bleeds top,” “bleeds left,” “bleeds two sides.” If your artwork does contain bleeds, they should extend at least 5mm beyond the area to be printed.

Blind Embossed
A pattern, which is stamped onto a sheet or envelope without gold-leaf or sink, leaving a raised impression on the paper.

Block Neg (Negative)
A film negative containing a positive image, used to make Cyrel photo-polymer plates for Flexo printing. Du Pont. See Cyrel

Reproduction paper, which receives its image during exposure by, direct contact with the negative in a vacuum device. The paper is then passed through a developer to produce the final (positive) image. Contact paper is ideal for camera-ready artwork.

Bronzing (Dusting)
This involves the process of applying gold dust onto specific areas, which is especially suitable for classical appearances, e.g. wine labels, can labels, wedding cards, etc.

Business Reply Envelope
A reply envelope, which is pre-printed with both a mailing address and postal indicia, showing that postage will be paid by the addressee. Postage and fees are collected when the mail is delivered. A Business reply permit is required. The lines printed on the RHS must be 15mm from the bottom for the OCR machine reading.

The thickness of paper, usually expressed in hundredths of a millimetre. (Like 0,09mm)

Camera -Ready
Artwork that needs no additional work or clean up before being photographed for printing purpose. Refers to good, clean, flat copy, usually a stat, or RC paper or a paste-up, printed in black or with dark ink.

Cartridge Paper
Uncoated paper with a base weight of more than 80gsm and less than 135gsm.

Clearsite Window/Acetate/Tricyte
A polystyrol film or acetate window, which is almost completely transparent, used mainly due to its exceptional clarity. This product is not biodegradable.

Clip Art
Artwork which is sold or distributed on printed sheets. It can be cut out and pasted onto mechanicals in situations where an artist is either not available or not necessary.

Close Registration
Also tight registration. The close alignment of two more print colours to form a complete image. Close registration tends to increase the set-up time before printing due to exacting tolerances. This is because with close registration, even a slight misalignment is readily noticeable.

Coated Paper
Paper that has been coated with white clay or enamel to provide a smooth printing surface. Coated stock is available with either a glossy or a matt finish. Coated Paper is not suitable for conversion.

Colour Chart
Colour Formula Guide, a book showing samples names or numbers, and printing ink mixing formulas.

Your envelopes can be printed in any combination of colours, ranging from single-colour to multi-colour work.

Colour Key
Also mechanical separation. A set of two or more acetate overlays, representing the colours to be printed. Used to indicate the position and register of each colour.

The receiver to whom goods are shipped.

Courtesy Reply Envelope/Self Addressed
An envelope, which is pre-printed with a mailing, address for reply mail. Unlike a Business Reply Envelope, it is not printed with postal indicia therefore postage must be affixed by the person who mails the letter.

Crop Marks
Markings on the margins of the film or artwork, showing the proper position and (if there are bleeds) the portion of the art to be printed.

Photo-Polymer plate which is used in the Flexographic printing process.

Deep Flap
The closure flap folds down over 90% of the bottom and side flaps of the envelope.

Dextrine Gum
Most used in the envelope flap gum. Dextrines are made from starch re-wettable gum.

Die Cut Envelope
A blank which is cut from a single sheet of paper using a solid or adjustable die. After it is die cut, the envelope is then folded in a separate operation.

Die Line
Proof of a constructed Positive or Negative.

A stainless steel blade angled over the screen roller, minimising the ink flow to be transferred to the Cyrel (Stereo)

Depth and texture are given to designs through accurate embossing.

Printing Flexo (Or Aniline)
Flexography. Rotary printing which uses flexible rubber/stereo’s and fast-drying liquid inks.

Flush Left (Or Right)
Aligned at the left (or right) edge of a block or type.

This process adds an extra dimension to any design, with a choice of various colours and designs in foils. Foiling can also be done on top of bronzing.

Four Colours Process Printing
A process, which uses black plus the three subtractive printing colours to reproduce all other intermediate, colours and shades. The four colours used are cyan (light blue), magenta, yellow and black.

Glassine Window
A vegetable-based parchment which can be recycled in the same bin along with paper. This environmentally friendly window material has a somewhat cloudy appearance as compared to poly or cello. Glassine can be adversely affected by changes in humidity.

Golden Kraft (Midas)
See paper.

Also grain direction. In a sheet of paper, the direction along which most of the fibres is aligned. The term “with the grain” means parallel to the grain of the paper. The folding edge should run with the grain in order to minimise cracking, when using solid printing.

Gravure Printing
Also Rotogravure Printing or Intaglio Printing. Uses a sunken or depressed surface for transferring the image. A copper wrap-around plate or cylinder with the image etched below its surface rotates in a bath of ink. The excess is wiped off the surface by a doctor blade. The ink remaining forms the image by direct transfer to the paper. By contrast, letterpress printing uses a raised surface and offset printing uses a flat surface.

An expansion pleat folded or scored into an envelope or pocket to give it greater capacity when filled.

An image which is formed by using dots of various sizes and shapes. In printing, continuous-tone art (such as a photograph) is reproduced using halftones, which are either created by photographing the original artwork through a screen or by manipulating the image on a computer.

In offset Lithography, an imperfection in artwork due to things such as dirt on the press or hardened specks of ink.

In-Line Printing
Printing done on envelope folding machines at the same time that the envelope is being made. Envelope folding machines employ Flexo printing methods, which use flexible Cyrel plates and fast drying fluid inks.

Inserting Equipment
Equipment which automates the process of stuffing envelopes.

Inside Side Seam
A side seam which is glued to the inside of the envelope, rather than to the outside.

Jet Press W & D 212/214
The trade name for a Litho offset press, especially designed for printing envelopes. Capable of perfecting and of printing up to two colours at the same time, this versatile press is ideal for printing business and catalogue envelopes in shorter runs off-line.

Jet Printing
Printing done on a Jet Press.

Job Number
A number assigned to a special or printed order after a signed PO has been received and before the work is completed and billed. Since no invoice number is generated until the envelopes are usually shipped, a job number is needed in order to track the order through the manufacturing process.

Jumbo Reel
A large reel of paper from where different paper reel or sheet sizes are cut.

Paper which is produced from wood pulp by a sulphate process which dissolves the lignin that binds the wood fibres together. Kraft has long fibres for added strength and is brown in colour. – 120gsm

Laid Paper
A fine paper, which is distinguished by, reflected parallel lines in the surface, These lines are formed in the paper manufacturing process.

Latex Gum
Also self-seal gum. A seal gum made from latex. No moisture is required. Both the flap and the seal area are coated with latex. When the flap is closed, latex comes into contact with latex, and a cohesive bond is created.

Common Trade Names of our industry: Touch ‘n Reseal, Autofix, Ready Seal, Multi-stick, Drylok and Simpli Stick.

Letterpress Printing
Printing which uses a raised surface for transferring the image. A form with raised type or electrotypes is placed on the bed of a platen press, or on the cylinder of a rotary press. Ink is applied to the raised portions of the form and brought in contact with the paper. By contrast Gravure printing uses a sunken or depressed surface, and offset printing uses a flat surface.

Line Art
Artwork, which contains no greys or middle tones. Any drawing which can be printed without the use of halftones.

Linen Finish
Paper with a raised surface design, simulating linen.

Also Offset Lithography – Litho printing. Printing which uses a flat surface for transferring the image. A metal plate is treated so that water will adhere every place except where the image is located. Water is applied and then ink. The moist areas refuse to accept ink. Next this plate transfers its image to a rubber cylinder which finally transfers it to the paper. By contrast, letterpress printing uses a raised surface and Gravure printing uses a sunken or depressed surface.

Lower Case
Letters which are not in capitals.

See paper.

This envelope is bigger than standard DL = ‘DIN’ LONG 110x220mm can be 115x230mm or 120x235mm. This could apply to C6 (114x162mm) which would be 114x170mm.

Multi Stick
See Latex

OCR Readable
Readable using optical character recognition (OCR) technology – automated equipment, which mechanically reads printed type. OCR technology is used by the SA Post Office to scan mailing addresses and print a barcode. Only certain typestyles such as Helvetica Medium are listed by the post Office as compatible with OCR.

Off Line
Refers to an operation, which is performed subsequent to the manufacture of the envelope. For example, because of the low speed to the process, attaching a string and button is always an off line operation.

Also inside tint or security inside tints (Opaque). A Flexo or Litho pattern or solid which is printed onto the inside of the envelope for privacy. This can be customised to client specifications i.e. repeat of logo or a picture, or simply by changing the colour ink used.

Outside Flaps
A side seam which is glued to the outside back of the envelope rather than the inside.

Outside Tint
A Litho pattern or solid which is printed over the entire outside of the envelope.

The overlay represents the shape of the punched blank (unfolded) but also indicates bleed and non-printed areas.

Additional quantities manufactured over and above the required amount of the order.

Term used i.e. DL oversize, which indicates an envelope larger in dimension than a DL and 115x230mm.

See PMS Colour/PMS chart.


  • Manilla – Brown colour 80/90gsm.
  • Golden Kraft – Golden Brown in colour 90/120gsm. (Midas)
  • Valet Paper – White in colour specifically designed by Sappi for envelope manufacturers.

Also mechanical. A background board to which various pieces of art or copy is attached according to the final layout.

Printing the front and back of the envelope at the same time.

A row of small holes or cuts so that the paper can be detached easily. i.e. bangtail envelope.

A lifting of the paper surface during printing. This occurs when pulling force (tack) of the ink is greater than the surface strength of the paper.

PMS Chart
The Pantone Colour Formula Guide. A book showing samples, names or numbers, and printing ink mixing formulas for Pantone colours. Pantone, Inc.

PMS Colour Guide
PMS stands for Pantone Matching System, a trademark of Pantone, Inc. PMS colours are usually identified by a three or four digit code number which helps printers and their clients to communicate using a common standard when specifying colours and inks for Envelope printing use only uncoated (U).

Punching Knife
A high-grade steel envelope die shaped to a size of an unfolded envelope. The die is pressed through sheets of paper to cut out individual envelope blanks.

Punching Marks
Lines drawn relevant to the punching process to allow positioning of the punching knife. These indicating marks should be printed in the lightest colour.

Pocket Shape
An envelope which opens on the short side.

This term identifies a product or substance as theoretically capable of being recycled into new products. The term does not imply that the product itself actually contains any recycled fibers or materials.

Recycled Paper
Paper, which contains fibres, obtained from previously manufactured paper that has been cooked and reduced back again into pulp. Recycled papers may contain either pre-consumer or post-consumer content or both.

Reel Web Press
Any one of several types of presses, which print, from continuous rolls of paper, rather than relying on a sheet fed process.

Register Marks
Also crossmarks. Crosses or other marks, which are added to the margins of the original artwork before, colour separation or photography. During printing, they are again aligned and can be used as a guide to assist the printer with proper colour registration.

The alignment of two or more print colours to form a complete image. Also refers to the proper positioning of print copy relative to the edges of the envelope or sheet of paper. See also Close Registration.

Remoistenable Hot Melt
Thomo plastic adhesive designed for use mainly on resealing of products such as envelopes and publicity material.

Reusable Envelope
An envelope that can be posted twice i.e. instead of a second reply envelope inside. (B.R.P.)

Run On
Further quantities of envelopes ordered and run at the same time as original order placed.

Roll Out
Further quantity of envelopes required as a repeat of a test run (material standing)

See Halftone.

Security Tint/Opaque
See Opaque.

Also colour separation. Separate film or stats for each colour, which is to be printed. Registration marks are used to indicate the proper position and alignment for each colour.

Simpli Stik
A longlife self-seal product with a release paper strip, which you peel off to seal the flap. Merpak trade name.

Size Chart
A chart printed showing sizes of envelopes most commonly used.

Special Envelope Styles
Tissue Envelopes, Money Envelope, Internal Office Mail Closure, Seed Bags, Single Tuck Envelope, Single Clip and Dopple Tuck.

Square Cut
Back flap cut into a diagonal square, usually appropriate for card or airmail envelopes.

Photo-Polymer plate which is used in the Flexographic printing process.

Synthetic Fibre
Lightweight Polyethylene Fibre paper interlocked in different directions. The paper is water resistant, brilliant white and non-tearable.

Test Run
Smaller quantity of envelopes ordered to do a test mailing.

Thumb Cut
A notch cut for easy access on the open side or end of a jacket or sleeve. Usually specified as “thumb cut face” or “thumb cut face and back”.

Inside or outside tint using a Flexo or Litho process to change the overall or part of the envelope colour during printing process.

The trade name which Dow Chemical uses for its clearsite window material (qv.).

A particular font used to construct written material.

A strong material made from spun-bonded olefin. Tyvek resists tearing and moisture and is acid free.

Uncoated Stock.
Paper which has no surface additives other than sizing. See Coated Stock.

Upper Case
Capital letters.

Shortage in quantity of the order placed.

“V” Shape
An envelope with a closure flap that is in the shape of a rounded V or triangular.

Valet Paper
See paper.

A process, which involves printing an UV Varnish onto, printed sheets to give a gloss finish.

Wallet Shape (Kern Wallet) (French Wallet)
An envelope which opens on the long side. This can also be referred to as a banker envelope.

Wash Up
The process of cleaning the roller, form or plate and sometimes the fountain of a press. A wash up is required each time the press switches to a job with a new ink colour.

Water Mark
A subtle design embedded in the texture of the paper itself. This design, which is formed in the manufacturing process, can be seen when the paper is held to the light.

W & D
Trade name of envelope machine manufacturer in Germany – Winkler and Dunnebier

Web Converting
Cutting, folding and gluing envelopes from continuous rolls of paper, rather than from pre-cut envelope blanks.

Web/Reel Envelope
An envelope which was manufactured using web converting technology.


Special Window
A window which are not standard 45x90mm and/or which is not in the standard position 20mm from LHS 15mm from bottom.

Merpak Standard Window

Size: Position:

  • C6 – 120x235mm 20mm LHS and 15mm from the bottom of the envelope.
  • C5 Wallet 20mm LHS and 60mm from the bottom of the envelope.
  • C4 Pocket 22mm LHS and 224mm from the bottom of the envelope.

Window Size: 45x90mm.

Merpak Special Window

Size: Position:

  • 115x235mm 20mm LHS and 15mm from the bottom of the envelope.
  • Window Size: 36x90mm.