An addition of from 2-3 per cent. of a special mineral oil for this purpose will impart a finish to the soap and 3-5 per cent. starch added prevents the soap from cracking in the frames. Other filling material as silicate of soda, borax, talc or silex are used. After the filling material has been thoroughly crutched through the soap it is framed, and, after being several days in the frame to solidify and cool the soap is ready for slabbing, pressing and wrapping.
In order to more definitely illustrate the composition of the mixture of fats and oils entering into the formation of a laundry soap a typical formula may be given for such a soap containing 40 per cent. rosin added to the amount of fats used:
lbs. Grease 7,000 Tallow 4,000 Corn Oil 7,000 Cottonseed Oil 3,000 Rosin 8,400
The following have been found to be satisfactory filling materials and are calculated upon the basis of a 1,400-pound frame of soap.
Sodium Silicate, 38°-40° B. 100 Mineral Oil 25 Sal Soda Solution, 36° B. 80 Borax 1
Sal Soda Solution, 36° B. 80 Mineral Oil 25 Sodium Silicate 60
III. Soda Ash 10 Sal Soda 55 Sodium Silicate 115 Mineral Oil 40 Brine (Saturated Solution) 10 Sodium Silicate, 38°-40° B. 100
IV. Sodium Silicate 100 Silex or Talc 200 Soda Ash 50
Sal Soda Solution, 36° B. 90 Sodium Silicate 50-60 Mineral Oil 25 Borax Solution, 25° B. (hot) 15
Chip soap is used extensively in laundries but is also used largely in other branches. It may be made either as a settled soap or by the cold made process.
To make a full boiled settled chip soap, proceed as directed under settled laundry soap. The kettle is stocked with light grease or a mixture of grease with corn oil or other cheap oils. For this kind of soap the rosin is eliminated.
Chip soap may be filled as well as laundry soap. This is done in the crutcher and the following adulterations are suitable.
lbs. Settled Soap 700 Soda Ash 35 Sodium Silicate 215 or Settled Soap 700 Silicate of Soda 560 Soda Ash 18 Carbonate of Potash, 26° B. 50
The cheapest method of drying is by running this soap through a drying machine and this is the procedure usually carried out for making dried chip soap.
To make chip soaps by the cold process a sweet tallow of low percentage of free fatty acid should be employed. The tallow is heated to 120° to 135° F. and the lye run in slowly at first and then the silicate of soda is added. The mass is then mixed until a finger drawn through the soap leaves a slight impression, then dropped into frames or barrels. Soaps containing a small percentage of fat should be well covered in the frame for twenty-four hours to retain their heat and insure proper saponification. The following formulae are suitable: