|The Story of
an account of paper-making from its earliest
known record down to the present time by
J.W. Butler Paper Company 1901
|Water Marks and Varieties of Paper Part 3
|The quality and value of coated paper depend upon the quality of
the body paper, the fineness of the clay and other ingredients
used in the coating, together with the perfection of its
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 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. Paper which has been so chemically treated that the color of its surface may be
altered by the action of light is known as sensitized paper. Under this general designation are included numerous
papers differing from each other in the details of manufacture, though the name is most commonly applied to paper
that has been floated in a bath of nitrate of silver, or coated with an emulsion of silver-nitrate of chloride. One of the
most common of papers included under the general term is that known in general trade as blueprocess paper, which
is prepared by floating white paper in a solution of potassium ferrocyanide. It is used for copying plans and maps, as
well as for printing photographic negatives. After exposure to the light for the proper length of time, under the subject
to be reproduced, the print is finished by immersion in several changes of clean water. Very similar to the blue-process
paper is the blue or ferro-prussiate paper, which is sensitized or made sensitive by being treated with a solution in
water of red prussiate of potash and peroxide of iron. This may be applied as a blue-prints coating to the surface of
the paper, or the latter may be floated upon the solution. When exposed to light under a drawing, those parts of the
sheet to which the light has access through the transparent portions of the drawing are more or less affected,
according to the greater or less transparency, as well as to the length of the exposure. When this printing has
proceeded as far as desired, the sheet is washed in clear water, and those parts that have been protected from the
light, become white, while those exposed to the light and affected by it take on, when dry, a permanent blue.
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