Paper – Glossary of Terms
There are many terms used when working with paper – here is a selection of some useful definitions:
Acid Free Paper
A paper which does not contain any free acid. Special precautions are taken during manufacture to eliminate acid in order to increase the longevity of the finished paper and to provide a sheet that is suitable for contact with metals.
A quality bulky paper, particularly opaque, with a rougher surface finish. It can be made in white or in colours, be deckle edged, and either laid or wove. A good printing surface is a feature of this grade which is often used for quality books.
This is a general term for higher quality woodfree coated papers which have a highly polished surface. Today the term is less used because of the introduction of more categories in the sector. However ‘real art’ is still used for those woodfree coated papers considered to be of the highest quality.
Name given to the base sheet which is intended to be off-machine coated or converted.
Blade Coated Paper
Paper coated by a process in which the freshly applied wet coating is smoothed and the excess removed by a thin flexible metal blade which bears on the coated surface.
A chemical treatment used to whiten, brighten and improve the performance of pulp.
Term applied to a paper above an accepted weight. The accepted cross-over point from paper to boards varies but in general would be around 180gsm. Below this weight are papers above this weight would be boards.
Paper, which during the paper making process becomes suitable only for repulping e.g. trimmings or paper that is out of specification. This re-used material which never left the mill is not regarded as recycled.
A term applied to the substance, thickness and feel of paper.
Paper subjected to smoothing and polishing between stacks of highly polished steam rollers (calenders), which can form part of the dry end of the paper machine.
A method of drying coated paper by contact of the freshly coated surface with a highly polished chromium plated heated surface. Cast coated papers have an extremely high gloss finish for top quality printing. The finish is obtained by the coating mix solidifying while in contact with the polished surface resulting in a similar polished surface to the paper.
Used in bank credit forms Clearing Banks Specification 1 must be 95gsm paper and of determined rigidity, surface smoothness, fold and strength characteristics. It’s chemically treated to prevent tampering.
Used in bank credit forms Clearing Banks Specification 2 must be an 80/85gsm paper and of determined rigidity, surface smoothness, fold and strength characteristics, with low background fluorescence for OCR readability.
Pulp made by means of chemicals that dissolve the bonding agent, called lignin, within the wood to separate the fibres.
A contraction of the words ‘continuous stationery’.
Cutting to Register
Operation of slitting and cutting watermarked paper so that the watermark design falls in a given position in every sheet.
Coating of paper or board twice on one or both sides.
ECF (Elemental Chlorine Free)
A common definition for pulp bleached without using elemental chlorine. Originally any of the bleaching techniques for chemical pulp, when no molecular (elemental) chlorine is used.
Resistance to colour fading.
Gloss can refer to the reflectivity of paper itself or of the printed result on it. Gloss of paper is measured by using a Gardner gloss meter, which measures reflected light at an angle of 75 degrees, and is expressed in Gardner gloss units – the higher the number the glossier the paper surface.
During manufacture the fibres in a web of paper naturally take up an alignment roughly parallel to the direction of travel of the web on the papermaking machine and this becomes the grain direction. Once guillotined down to sheet form, papers are called ‘long grain’ if the fibres are parallel to the long edge of the sheet, or short grain if parallel to the short edge. Grain direction can affect stiffness, folding, creasing and printing characteristics.
Papers for printing and writing.
Gsm or gm2 or g/m2
These all mean ‘grams per square metre’ and are a measure of the weight of a paper. For example if an 80gsm paper was in a sheet size of 1000mm x 1000mm i.e. a square metre one sheet would weigh 80 grams.
A spot on a printed sheet caused by dust, lint or ink imperfections; particularly noticeable on solids and half tones.
A mill which starts with logs or wood chips and produces wood pulp which it then processes to make paper without intermediate drying.
High quality board made in white or colours with a bright clear appearance, particularly used for visiting cards and similar high quality printed work.
A light form of mineral coating, achieved by supplying the surface sizing press of the papermaking machine with coating material instead of normal surface sizing solution.
Lightweight Coated (LWC)
Coated paper below approximately 60 gsm.
A coated paper with a dull smooth finish.
Pulp produced using a non-chemical process and instead using a grinding process. Papers made from mechanical pulp often have good opacity and bulk but yellow more quickly than paper produced from chemically made pulp. Newspapers are often printed on papers having a proportion of mechanical pulp.
An acronym meaning ‘no carbon required’ referring to a noncarbonless paper originally introduced by the National Cash Register Company but which is now more commonly referred to as carbonless paper.
Neutral Sized Paper
Paper sized with neutral size i.e. neither acidic nor alkaline. Neutral sizing gives the paper enhanced longevity.
The extent to which a paper is capable of obscuring matter printed on the other side or on an underlying page. A paper with good opacity is one on which the printing on one side cannot be seen from the other under normal conditions. Usually expressed as a percentage (%).
An ancient writing material made from stems of the papyrus plant. Although the word ‘paper’ is derived from papyrus, papyrus itself is not paper in the normal sense.
Envelope – Glossary of Terms
There are many terms used when working with envelopes – here is a selection of some useful definitions:
Reverse side of a wallet or banker.
Special style of wallet, incorporating a perforated flap, extending from the throat.
Style with an opening on the long edge, and a diamond shape flap. Described as either high cut or low cut depending on the throat.
Paper with a weave effect finish traditionally used for heavyweight manilla papers.
Envelope manufacture using sheets of paper.
Where the print runs off the edge of the paper.
Generally a pocket style, made with a cardboard back to provide a rigid envelope.
Business Reply (BRE)
A reply envelope with pre-paid postage using a business reply licence. Most often used with business to business mailings.
Where the contour on the top flap of the envelope matches the leading edge of the back flap.
Printing technique used on the inside or outside of an envelope to give a tinted or colour effect.
A wallet construction, but with the side seams folded on the outside of the backflaps. Used primarily for mailing wallets.
The front of an envelope.
Paper based material, used for windows and some photo envelopes
A strip of gum applied to the flap that needs to be dampened to help seal the envelope.
An open end envelope with expandable sides.
Strong, glazed manilla paper. Also produced in white and bleached kraft.
An envelope format where the longest side of the window runs parallel to the long edge of the envelope.
An envelope that runs efficiently through an automatic mailing machine (see mailing wallet).
Machine Glazed (MG)
Smooth finish on one side of the paper, particularly common on manilla paper.
A style of envelope that can be used in an automatic mailing machine.
Remoistenable gum on both the flap and the backflap for extra security.
Pocket with an ungummed internal flap that folds over for security but can be opened for postal inspection.
The degree of show through or transparency of the paper, i.e. an envelope with good opacity will not show the contents enclosed.
Printed solid, or design inside an envelope for security.
Envelopes that have been taken from the print run and sent to the client.
Printing onto already manufactured envelopes.
Envelope style with one side or centre seam, a bottom flap and an opening on the short side.
The measure of air in the paper that allows absorption of ink. The degree of porosity can affect the quality of the printing, and can also affect the efficiency on some automated enclosing machines.
An upright envelope where the long side of the window is parallel to the short side of the envelope.
Post Office Preferred
Series of recommendations for envelopes, set by International Postal Administrators.
A cut out strip which can be pulled to reveal a gimmick or open an envelope.
High-speed envelope manufacturing technique, using reels of paper.
Latex gum on the flap and back of the envelope, that gives instant adhesion but can be opened and closed several times for postal inspection.
Fold between the flap and the throat of wallets and pockets.
Lines scored on the outer flap of self-seal envelopes only, which split the flap in several places when it is opened. This makes it possible to detect if the envelope has been tampered with.
Two strips of latex on the envelope flaps that seal with each other on contact.
Top of the side flaps on a wallet. A critical design aspect for most automated inserting machines.
Two seams on a wallet/banker, gummed to the back flap.
Envelope with self-adhesive flaps, protected by a release strip to give extended shelf life.
Gap between the score line and the back flap of a wallet. A critical design aspect for most automated inserting machines.
Shape cut from a topless pocket or wallet, to enable easy access to the contents.
Pocket or wallet style without a flap, although a lip may be left.
Envelope style with two side seams and the opening on the long edge.
A paper containing up to 50% mechanical pulp, the remainder being chemical pulp.
An agreed range of paper sizes.
Examples: RA1 = 610 x 860mm RA2 = 430 x 610mm RA3 = 305 x 430mm
A continuous length of paper wound on a core, irrespective of diameter, width or weight. Reels can be rewound into smaller reels or slit into coils.
Reel to Reel
A machine on which the material is supplied in reel form and comes off the machine also in reel form.
The ability of a paper and board to perform and run through a printing press or on converting machinery without problems.
Self Contained Carbonless
A carbonless type paper which can generate an image itself through the application of pressure. Self contained carbonless papers work without the need for other top, middle or bottom carbonless sheets.
An agreed range of paper sizes.
Examples: SRA1 = 640 x 900mm SRA2 = 450 x 640mm SRA3 = 320 x 450mm
The weight of paper or board, shown by scales, taken from a sample. The weight is almost entirely defined by grammage per square metre of a single sheet (g/m2).
TCF (Totally Chlorine Free)
Pulp produced without any chlorine or chlorinated chemical compounds.
A pulp or paper which contains no mechanical wood pulp. In commercial practice a small percentage of mechanical fibre is usually acceptable. It does not denote paper or pulp made from materials other than wood.