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ABSORBENCY
The spectrum of which a paper will take up and hold a liquid.
ACID-FREE PAPER
In principle, paper that does not contain any free acid. Special safety measures are taken during manufacture to eliminate any active acid that might be present in the furnish.
ADDITIVE
A mineral, chemical or dye added to pulp, secondary fiber and coatings to give it special qualities such as fuzziness.
AIR DRIED PAPER
Paper dried while being exposure to warm air.
AIR-DRY PULP
Technically, pulp of which the moisture content is in balanced with the ambient atmosphere. Commercially, pulp at a theoretical moisture content agreed between the buyer and the seller (e.g., 10 per cent is common).
AIR-KNIFE COATED PAPER
Paper coated by a process where the freshly applied wet coating is smoothed and the leftover removed by means of a jet of air discharged from a slit orifice placed at an angle to the web.
AIRMAIL PAPER
Paper made in the lightest material consistent with strength and a good surface, for reasons of postage costs. Generally produced in white, off-white or pale blue for stationery purposes, usually below 40g/m2. Manifolds and lightweight bonds are also often known as airmail papers.
ALUM
A term commonly, but incorrectly, applied in the paper industry to different qualities of aluminum sulphate.
ANTIQUE
A characteristic low degree of surface finish that characterize certain commercial descriptions of paper such as Antique Wove, Antique Laid, etc.
ANTI-RUST PAPER
Paper containing added ingredients that give it the property of protecting the surfaces of ferrous metals against rusting.
ANTI-SET-OFF SPRAY
An apparatus used on the delivery end of the printing machine to prevent set-off by projecting a fine spray of liquid or powder at the sheet.
AOX
Adsorbable Organic Halogens. AOX declare the amount of organic chlorine compounds in effluent produced as the chlorine chemicals react with the residual lignin in the bleaching of pulp. A safe AOX limit is easier to achieve using chlorine dioxide than with chlorine.
APPARENT DENSITY
The quotient of the grammage of a paper size and its thickness in micrometers.
ART PAPER
This is a general term given to woodfree coated papers, which has traditionally referred to papers in the upper quality bracket and which have a high polished surface. “Real Art” is still used for those woodfree coated papers, gloss or matte, which are considered to be of the very highest quality though Today the term is not very common because of the introduction of more categories in this sector.
ASH CONTENT
The amount of material that remains when a sample of paper is burned under controlled conditions so that all ignitable matter is removed. The ash derives from the mineral loading in the paper.
