The art of paper-making; a practical handbook of the manufacture of paper from rags, esparto, straw, and other fibrous materials, including the ... and appliances used to which are adde

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1890 Excerpt: ...the preparation of resin soap--Powdered resin....... 4-80 parts. Soda crystals at 80 (French alkalimeter).. 2-22 „ Water 100 „ Theoretically speaking, only 2-45 parts of alum would be required to precipitate the resin; but the waters, which are almost always calcareous, neutralise part of the alum. Crystals of soda are much more expensive than soda ash, but on account of their greater purity they are sometimes preferred to the latter. At the present day the resin soap is preferably made by dissolving ordinary resin with a solution of carbonate of soda under boiling heat in a steamjacketed boiler, the class of paper to be made governing the quantity of resin to be employed. The boiling usually requires from two to eight hours, according to the relative proportions of soda ash and resin used--the greater the proportion of soda used the less time is required for boiling--the process being completed when a sample of the soap formed is completely soluble in water.... About 3 lbs. of resin to 1 lb. of soda is the usual proportion. The resin soap is cooled after boiling by running it into iron tanks, where it is allowed to settle, the soap forming a dense syrup-like mass, and the colouring matters and other admixtures of the resin rising to the top are easily removed. It is important to run off the mother liquor (ley) containing the excess of alkali, for when the soap is used it consumes the alum to neutralise it." When the impurities and ley have been removed the soap is dissolved in water, and if, from imperfect boiling, a portion of the resin is found not to have been saponified, a small quantity of a strong solution of soda crystals is added to the water used for dissolving the soap. Where starch is used for stiffening purposes, the soap is mi...