This section is from the book "American Library Edition Of Workshop Receipts", by Ernest Spon. Also available from Amazon: American Library Edition Of Workshop Receipts.
What is asserted to be an effective process for waterproofing woollen goods has come into use among German manufactures, the cloth in this case gaining considerably in weight, and, though perfectly waterproof, impedes neither air nor perspiration. A solution is made of 100 parts alum, 100 of glue, 5 of tannin, and 2 of soluble glass, by dissolving alum in a moderate quantity of boiling water. The glue is steeped in cold water until it has absorbed twice its weight of water, and is then dissolved by heat; the tannin and soluble glass are well stirred into the solution of glue, to which the alum solution is then added, and the whole stirred and allowed to cool. 2 lb. of the gelatinous mass is boiled for 3 hours in 3 gal. water, fresh water being constantly added to allow for evaporation. The bath is now permitted to cool to 80° C. and in this the material to be rendered waterproof is kept for 1/2 hour, then withdrawn, and the moisture allowed to drip from it for several hours. Finally the cloth is stretched on a frame, and dried at a temperature of 50° C, then calendered.