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PAPER AND ITS USES
Non-curling Gummed Paper.—Specially prepared gummed paper, the body paper being made as nearly free from stretch as possible, and the coating of gum, when dry, is broken into fine particles by drawing the finished paper over a steel bar. This prevents the film of gum from acting as a single surface, and only when the particles again cohere is the non-curling property destroyed.
Oiled Paper.—See Manifold Paper and Stencil Paper.
Onion Skin.—A term applied to thin, hard, highly glazed translucent papers, because of their resemblance to the thin outer skin of the onion.
O. W. Papers are specially prepared for water colour drawings, the rags being reduced to pulp without chemical treatment, without bleaching. The papers are tested for chemical purity. Usual sizes of drawing papers.
Pamphlet Papers.—Tinted papers of various substances, used for covers of pamphlets, and for a large variety of jobbing work where a paper of fair weight is required.
Parcel Tape Paper is supplied in various widths and qualities, from ordinary gummed paper to kraft brown with gummed back; used for fastening small parcels instead of string or wax. Supplied in coils for use with a special damping machine.
Parchment Papers.—Properly, parchmented papers, i.e., the cellulose of which the paper is composed is altered in character to resemble parchment. A web of unsized paper is passed through a bath of strong sulphuric acid, which attacks and dissolves the cellulose, changing its fibrous form. Before the change is complete the paper is washed, the acid is neutralised, and the paper dried. The paper shrinks considerably, but is greaseproof and much stronger than before treatment. Vegetable parchment and pergamyn are alternative names for the same material. Used as an impervious packing paper for provisions, for tea packing, jam covers, etc.
Pasteboards.—Cardboards formed by pasting fine papers to middles of inferior quality. Distinct from triplex, ivory, and pulp boards.
Pastings.—Papers for pasting down; facings for paste-
