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Screen-Plate Patents 499
already in band form. The threads could be guided on to glass, led along a glass table, gelatin being used to cause adherence. The provision of a wide band along one edge for registration was disclosed. F. de Mare119 also proposed woven threads and later colored threads120 were to be merely juxtaposed. Schmelik121 proposed to repeatedly card the fibers and thus obtain a more intimate mixture, and the individual fleeces were then to be saturated with a filling material, like colored collodion or rubber solution, then combined by pressure and cut.
Various Processes. — The first method to be dealt with is that of J. H. Christensen122 who would apply emulsified particles to a support. Solutions of gum arabic and dextrin were dyed up, emulsified in gum dammar solution, then thinned with turpentine which removed most of the resin, and the particles were allowed to settle down. They were then suspended separately in benzine to which was added carbon tetrachloride, kerosene and asphalt. The solutions were then mixed and poured over a support coated with rubber; this latter swelled and held the lower globules and excess ran off, if the support was held in a slanting position. Later123 emulsification of dextrin or resin solutions in dammar solution in turpentine was proposed, and the globules were repeatedly washed with turpentine, and finally suspended in petroleum spirit. Later still124 Christensen coated the globules with a tanning substance that would not act on the support. It was also suggested by the same inventor125 in order to avoid loss of brilliancy by mordanting dye particles, to mix basic dyes with alcoholic solutions of tannin, thus preventing the precipitation. Or tungstic, molybdic or phospho-tungstic acids rendered basic with ammonia might be used. The mixtures were to be atomized or emulsified and the particles applied to a suitable support, and the tannate particles thus mordanted, while in the case of acid particles an acid might be used. For holding the particles, collodion with a small proportion of sodium oleate was to be used.
The Aktiengesellschaft f. Anilinfabrikation126 proposed to atomize solutions of dextrin by compressed air, saturated with aqueous vapor into a chamber. The particles were allowed to fall on to a layer of turpentin flowing over an inclined plane. The three dyed emulsions were sprayed over a tacky support. S. E. Sheppard127 would use cellulose nitrate or other ester, with or without camphor as latent solvent, dye the same with basic dyes, then emulsify in a colloid. For the dyes it was advisable to use the oil-soluble kinds, known as Sudan, for instance, for red, spiritsoluble red OG, and malachite green. Various methods might be adopted to convert water-soluble dyes into spirit-soluble ones, as by the precipitation of a basic dye with tannin, and the tannate thus formed might be prevented from insolubilizing gelatin by treatment with tartar emetic or other antimony salt. Ethyl and methyl alcohols should be used to dissolve the tannated dyes and in the case of cellulose acetate the alcoholic solution