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4. The Papier Mache Matrix



The papier-mache (literally, mashed paper) matrix was first successfully used for casting stereotypes for book pages in France in 1848. Charles Craske, an engraver of New York, introduced the method into the stereotype trade of the United States in 1850, and in 1854 he stereotyped a page of the "New York Herald" and later made stereotypes for other New York newspapers.

The modern wet stereotype "flong," in common use today, consists of several layers of special paper pasted together to form a thick sheet. The base is a sheet of special soft stock similar to firm blotting-paper, such as is used between leaves of small blank books. Three or four sheets of strong, white tissue are next added, each sheet except the last being uniformly covered with the paste. The pasting must be done with great care so as to cover the entire surface of each sheet and at the same time to press out all air bubbles. The sheets must then be pressed smoothly but not squeezed so hard as to force the paste out and must be kept moist until used. In newspaper syndicate plants, the "flong" is made automatically by a specially devised machine into which the various kinds of paper used are fed from rolls, the pasting and cutting into sheets being mechanical.

In molding a papier-mache matrix, the moist "flong" is laid on the original molding form to be duplicated, the molding form being in place on the table of the molding press. The "flong" is covered with several blankets of thick felt and the table of the molding press is then automatically moved in under a powerful roller which squeezes the moist flong down into the form. At the end of its travel the table is automatically brought back again under the rollers to the position from which it started. The speed of the roller and the table is synchronized to obviate any possibility of the mat becoming wrinkled by sliding.

The molded matrix and the pattern with the blanket still on it is then transferred to the drying press, in which under a hot platten it is again squeezed and allowed to remain for a few minutes until the moisture is completely expelled from the molded flong. The drying press is kept at a high temperature, usually by steam heat.

The matrix thus dried out to a thick, flexible cardboard is then ready for the casting of the stereotype, which is done by pouring molten stereotype metal against the face of the matrix placed in a casting-box designed for this purpose. A successive number of stereotypes can be cast for the same mat before it is injured by the hot metal. For job-work stereotyping the casting-box is flat, and the molten metal is either poured by hand or automatically pumped in the casting-box.

After the stereotype is cast it is flattened, rough shaved, smooth shaved, bevelled or blocked on wood; the wood base trimmed and then planed type-high for printing press use.

The large daily papers cast the full-page stereotype from which the paper is printed in an automatic casting machine which forms a curved plate, trimmed and bevelled, to fit the cylinder of the press.

Stereotyping was for many years the chief means of making plates for books and also for commercial printing. It has several advantages. The first, obviously, is the advantage which it shares with several other methods of providing a solid printing plate made by molding from an original form of type or engraving. Its peculiar advantage, however, is that it is the quickest method of producing a duplicate plate from an original.

In comparison with electrotyping, however, it has two distinct disadvantages. One is that it is not adapted for reproducing the fine lines of engravings and type faces. In addition it is comparatively shallow and does not possess a sharp, clean printing face. The other disadvantage is that a stereotype is relatively soft and quickly worn.

Stereotypes have been made more durable, to withstand the wear of printing, by the deposition of a film of harder metal--copper or nickel--on the face of the plate after it has been cast. This, however, is not satisfactory, as it involves not only another operation, but also makes an already shallow printing plate that much shallower and increases the probability of it printing "dirty," which is one of the chief objections to the stereotype in itself. This practice is not recommended.