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ALPHABETICAL LIST OF PAPERS
127
the diagram is faithfully recorded. A good quality paper is coated with a mixture of glue and zinc oxide, usually applied by hand and finished in the same way as art papers. Cheaper metallic papers are coated with barium sulphate.
Middles.—The materials for middles (of pasteboards) vary from waste paper to all-esparto fibre. Grey middles contain a large proportion of waste, mechanical wood and added mineral matter, while white middles are usually free from mechanical wood and of very fair strength. Made on the Fourdrinier machine, and left with machine finish, in order that the subsequent pasting of facing papers may be more thoroughly performed. In addition to their use for pasteboards, middles are used for tramway and bus tickets, frequently being tinted in the pulp.
Millboards are made from various waste fibres and waste papers. Hand-made and the best machine-made boards are made from hemp and flax fibres, the commoner machine-made from waste papers with or without long fibred material. The raw materials are reduced to pulp (the stronger materials boiled and beaten), made into boards in hand moulds or on special board machines, pressed, dried, heavily rolled, trimmed to size. Used for binding, boxmaking, portmanteaux, carriage panels, etc. (see page 143 for sizes and substances).
Mould-made Papers come between hand- and machine-made papers, having most of the characteristics of hand-mades. The moulding is mechanical, but the other operations are carried out as for hand-made papers. Four deckled edges will be present.
Music Papers, used for printing sheet music, are thick printing papers with a moderate amount of sizing, and with machine finish, making an easy printing surface for music type, plates, or lithographic surfaces. Usual size: demy, 20½ inches by 14¾ inches, 24 to 28 Ib. per ream of 480 sheets.
News.—Common printing papers, containing 60 to 80 per cent, of mechanical wood, a small amount of loading, and very little sizing. Suitable for news and other work of an ephemeral nature. Supplied in reels or sheets.
