THE OZOTYPE PROCESS.
The paper for this process can be pur chased ready for use. It is said to be ordinary paper sensitised in a solution of bichromate of potash, manganous sul phate, alum, and boric acid. This paper is exposed beneath a negative, of the class usually employed for similar processes, until a brown image appears, showing just a little detail under the densest parts. The image produced is a positive, and so forms a direct guide as to the printing action which has taken place. Next a sheet of ordinary carbon tissue, or some such pigmented col loidal substance, is immersed in a solution 4 hydroquinone, acetic acid, and ferrous mlphate, and squeegeed down upon the support, which has previously )een coated or immersed in a 2 per cent. .olution of gelatine. The time of Muller don in this bath is one minute, and the irints may be immersed with it and the wo withdrawn together in contact. The citteegeed print is then allowed to dry, vhich should not take too long, and is >oaked in cold water for about twenty ninutes It is then developed in the same ,vay as already described for single trans development, the print merely washing in cold water, and may be dried. face up, on blotting-paper.
MATEtivas REQUIRED.
The novice will, of course, succeed best with ready-prepared materials. A 2-oz. bottle of sensitising solution, sufficient tc cover sq. ft. of surface, costs ls. This area can only be covered by applying the solution with extreme care with a brush. Pigment plasters may be obtained of the colours usual for carbon tissue, including special brown, sepia, warm sepia, red chalk, engraving black, warm black, mariiu blue. ;ea green, and The3 are supplied in hands or in cut sizes. A dozen pieces half-plate size cost ls. Sam ple packets containing a variety of colours may be obtained. Special brushes are sold for coating, but any fair-sized flat brush (such as that shown in Fig. 302). if perfectly clean, will answer the purpose Special paper for coating is also supplied. three sheets costing ls. Double transfer final supports may be used instead, ant ordinary carbon tissue instead of the pig ment plasters. The solution for soakinf the tissue consists of hydroquinone 10 grs. ; acetic acid, dram ; water, 1 pint