Glazed paper is one of the most interesting and useful forms of coated paper. The glazing is done by two processes, known as friction and flint glazing. In either process the method of coating, up to and including the drying, is practically the same as that followed in the coating of other papers, except that wax is mixed with the coating to act as a lubricator, and to permit of securing the desired glassy finish.
In friction-glazing, the paper is passed through a friction calender, which consists of a cotton roll and a chilled iron roll, the latter revolving at much greater speed than the former, the friction generated giving the paper a very high polish.
In the flint process, the paper is fed into a special burnishing machine, and passes over a groove in which operates a flint-stone, fitting closely in the groove and working back and forth upon and across the sheet. As will readily be seen, this is a very slow process as well as expensive, although it produces a finish, higher and more lasting, than can be secured by the friction method.
Paper made by the two processes can be distinguished by the lines appearing on the flint-paper made by the stone in its travels across the sheet.
Glazed papers are used largely in the manufacture of boxes and numerous fancy articles.
♦Lithographic stock♦
Lithographic paper is a product especially prepared to take impressions from stones in lithographing. For ordinary use, common book or print papers are employed, but these are usually given extra care and attention in the course of their manufacture; the stock is so manipulated as to not only secure the desired quality and finish, but also to counteract the tendency of the paper to stretch, which if not overcome is apt to destroy the register and injuriously affect the quality of the work. The better grades of lithographing-paper are made by applying a clay coating especially prepared to bring about the desired results.
Asbestos-paper is made by combining paper pulp and the mineral amianthus. Its fireproof and non-conducting qualities make it a staple commodity for many purposes, such as drop-curtains for theaters, insulation of electric wires, packing of steam-pipes, etc.
Tar-paper is a coarse, thick paper soaked with a tar product, and used for covering roofs and lining walls, to secure warmth and dryness.
Paper coated with the white of eggs is known as albumen-paper, and is employed as a vehicle for silver prints in photography.