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The German "Porosin" Dry Mat

( Originally Published 1927 )

An advance step in the making of stereotype dry mats was made in 1895 by HERMANN SCHIMANSKY of Berlin, Germany. He contended that dry mats made in accordance with the specifications of prior inventors were so constituted that the free spaces were to remain white in the printing were filled up at the back of the matrix by covering with pieces of cardboard, as otherwise the hot lead would press down the very thin matrix in these spaces during the casting. Schimansky's invention (patented in 1899), was supposed to obviate this drawback and consisted in using perfectly dry matrices of vegetable fibre which were characterized by great porosity produced artificially, so that the impression of the type to be stereotyped takes place by simply destroying the porosity at the pressed parts, thereby rendering the mats directly suitable for the casting. Thus Schimansky claims he obviated the manipulation of covering up ("backing up") the free spaces, as his mat retains its original thickness at all free places which are not impressed. Schimansky recommends for the making of his mats all kinds of vegetable fibres—such as wood, cellulose, hemp, cotton or flax. In order to obtain the porosity of the mats, the inventor proceeded as follows : The fibres are first immersed in sodium carbonate and then in an acid, for example, vinegar—thereby developing as a gas carbonic acid, which effects the loosening of the mat. In this manner the porosity of the mat is obtained by loosening alone. Presumably the parts of resinous matter clinging to the fibre dissolve. In order to bend the fibre to form a mat, the fibrous material is treated in a long-sieve (Fourdrinier) paper-machine. Finally these mats are coated on one side with a thin coat or layer of starch paste, to which, five per cent of glycerine has been added, in order that the adhesion of the metal to the vegetable fibre may be obviated in the casting. The matrix thus produced ready for use may be kept in stock in any quantities in printing shops and used at once when required. Schimansky gave his dry mat the name "Porosin Matrix."

All these improvements did not permit of obtaining a matrix of sufficient depth and faultlessly smooth surface, being that the Eastwood as well as the Schimansky mat did not possess a surface which could receive sharp and sufficiently deep impressions from the type without tearing. On the other hand, the mats were not firm enough to allow the formation of sufficiently deep interstices at the blank spaces of the type which could resist the pressure of the poured-in metal on repeated casting. Another drawback of these first dry mats was that the texture of the paper employed made itself appear on the cast mold.

JOHANN EGYD WEIGL of Vienna undertook in 1901 to remedy these drawbacks by using a different process, which he claimed produced a plastic and impressionable dry mat, which would neither crack nor tear, and having a perfectly smooth surface. Weigl's mat was practically a wet mat, made almost identically in the same manner as a wet mat, namely by pasting different sheets and layers of paper together with different pastes, then drying same and stereo-typing with this mat as per the cold process. The single sheets are thoroughly bound thru calendering and after drying form a single indivisible matrix. Weigl manufactured his dry mat by brushing a sheet of supple, plastic cardboard with a paste of vegetable glue, glue of albumen and alcohol to which was added glycerin and calcium chlorid, laying on a gauze-like fabric prepared in mucilage of gelatin and pressing there-over a sheet of unsized paper, the outer side of which unsized paper was coated with mucilage of carrageen-mass and albumen glue and pressing thereon several sheets of tissue paper. It is very easy to understand that such a manufacturing method would tend to make the price of the mat out of all question.

The patent rights upon the Schimansky invention were acquired and the manufacturing of such dry mats was carried on by a paper factory in Southern Germany. The results, however, obtained in the beginning with the new dry mat did not warrant the making and selling of the product on a commercial scale. The factory simplified the manufacturing process, finally making a good dry mat, which it sold to German and foreign newspaper offices and which is still marketed as the "Porosin" mat. Schimansky's dry mat was adopted by the great German daily "Lokalanzeiger" of Berlin, and based upon this success, the inventor made a trip to the United States with the intention of disposing of his American patent. Several paper mills were more or less interested; Schimansky, however, returned home without having met with the hoped-for success.

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