TREATMENT OF SETTLED SOAP.
Cleansing—Crutching—Liquoring of Soaps—Filling—Neutralising, Colouring and Perfuming—Disinfectant Soaps—Framing—Slabbing—Barring—Open and Close Piling—Drying—Stamping—Cooling.
Cleansing.—After completion of saponification, and allowing the contents of the pan to settle into the various layers, as described in the preceding chapter, the actual soap, forming the second layer, is now transferred to the frames, this being generally termed "cleansing" the soap. The thin crust or layer at the top of the pan is gently removed, and the soap may be either ladled out and conveyed to the frames, or withdrawn by the aid of a pump from above the nigre through a skimmer (Fig. 1), and pipe, attached by means of a swivel joint (Fig. 2) (which allows the skimmer pipe to be raised or lowered at will by means of a winch, Fig. 3), to a pipe fitted in the side of the pan as fully shown in Fig. 4, or the removal may be performed by gravitation through some mechanical device from the side of the copper.
Fig. 1.—Skimmer, with flange for attachment to skimmer-pipe.
Every precaution is taken to avoid the presence of nigre in the soap being cleansed.
Fig. 2.—Swivel-joint.
The temperature at which soap may be cleansed depends on the particular grade—soaps requiring to be liquored should not be cleansed too hot or a separation will take place, 150° F. (66° C.) may be taken as a suitable temperature for this class of soap; in the case of firm soaps, such as milling base, where cooling is liable to take place in the pan (and thus affect the yield), the temperature may be 165°-170° F. (74°-77° C.). This latter class of soap is generally run direct to the frames and crutched by hand, or, to save manual labour, it may be run into a power-driven crutching pan (neutralising material being added if necessary) and stirred a few times before framing.