An initiative in the UK designed to classify the type and amount of recycled fibre in a paper product. The scheme grades four types of waste used in paper manufacture, as follows: A - Woodfree, approved own mill waste (waste that has not left the mill. i.e. mill broke). B - Woodfree unprinted waste (waste that has left the mill but not reached the consumer, typically from the printer or converter). C - Woodfree printed waste (post consumer waste, collected from homes, offices etc). D - Printed mechanical waste (post consumer waste, typically newspapers). To be classified as recycled the grade has to contain no less than 50% of the total fibre from any combination of the above sources, with the percentages given for each. Therefore Cairngorm is 15A/65B/10C (90% recycled in total with the remainder being virgin fibre).
Abrasion resisitance
The resistance of a surface to being worn away by rubbing or friction. A measure of toughness more than of hardness.
Acid Free Paper
A paper manufactured to a neutral pH reading. Used for fine art prints, limited edition printing, permanent records and to protect other materials where contact with paper acidity would be harmful.
Additive
A mineral, chemical or dye added to pulp and coatings to give it special qualities such as opacity.
Adhesion test
Test methods used to determine the adequacy of ink coating adhesion to a substrate. A common test is the Cross-cut tape test.
Ageing
The deterioration of paper properties with time. Sunlight and heat accelerate loss of strength and brightness.
Air Resistance
The rate at which air penetrates through paper. A property important to control for some paper requirements, i.e. to prevent the excessive penetration of liquids and to give print gloss, freedom from blistering of coated paper when the ink is heat set, and to allow sheets of paper to be picked up individually by air suction pads of printing press feeders.
Airmail
Papers made in the lightest substance (usually below 40g/m2) for reasons of postage costs, consistent with strength and a good surface. Generally produced in white, off-white or a pale blue for stationery purposes.
Angel Hair
Undesirable fine threads of ink caused when the ink pulls away from the printed surface. (see cobwebbing).
Antique Finish
A printing paper surface with a rough finish but good printing surface, valued in book printing for its high volume characteristics.
AOX
Adsorbable Organic Halogens. Collective term for the halogen compounds (chlorine, fluorine, bromine and iodine) bound to organic substances, for example in waste water from the mill. The compounds arise when bleaching with chlorine-containing chemicals although they can also occur naturally and are potentially detrimental to water quality. The lower the AOX level the better.
Archival Paper
A paper with long-lasting qualities, normally 100 years, acid free, lignin free, usually with good colour retention.
Ash
Mineral residue left from burning a sample of paper to determine the percentage of filler it contains.
