Preparation of the reserve or resist paste

—Melt in a kettle 2 1 ⁄ 2 libs. of rosin; 1 lib. of suet: mix well, and put it into the basins F G . By means of steam the reserve is kept melted, as well as the false colour upon which the sieve floats. The piece of silk being laid upon the table, and the reserve spread upon the frame, the printer heats his block, which should be mounted with lead, if the pattern will permit, upon the little table L . He takes up the colour from the frame, and transfers it instantly to the piece. He must strike the block lightly, and then lift it, lest, by its cooling, it might stick to the silk. When the table pattern is completed, he dusts it over with sand, and proceeds to another portion of the silk. The piece must not be taken out of the stretch till it is quite dry, which requires usually 6 hours. Let us consider first the most common case, that of a white upon an orange ground. We shall afterwards describe the other styles, which may be obtained by this proce . The piece, being printed and dry, must next be subjected to the mandarin ing operation. IMG:4147767755307473660_illo0241.png:Mandarin ing apparatus The apparatus here employed consists of a sandstone trough A B C D , fig. 249. Upon the two sides, A C , B D , of this trough are fixed two wooden planks, pierced with a hole an inch from the bottom to receive the roller E , under which the piece pa es. In this trough the acid mixture is put. That trough is put into a wooden or copper trough, F G H I . Into the latter, water is put, which is heated by means of steam, or a convenient furnace. Before and behind are placed two winces, or reels, K L : one serves to guide the piece in entering into the trough, and the other in its leaving it. The piece falls immediately into a stream of cold water, or, failing that, into a large back, containing a mixture of chalk and water. The two winces are moved by handles: the velocity is proportioned to the action of the acid. The wince L ought to be higher than K , to allow the acid to drain off. Fig. 250. shows a section of the apparatus. The temperature of the acid mixture ought to be maintained between 95° and 100° F.; for if it be raised higher, the resist would run the risk of melting, and the impre ion would become irregular and blotty. The proportions of the acid mixture are the following:—1 gallon of water; and 1 gallon of nitric acid, of spec. grav. 1·288, which may be increased with the strength of the silk. It should be a little weaker for chalys. For the strong greens it may be 2 measures of acid of 1·288 to 1 measure of water. The duration of the pa age through the acid should be 1 minute at most.