SEMI-BOILED LAUNDRY SOAPS.

It is advantageous at times to make a laundry soap by a method other than the full boiled settled soap procedure as previously outlined. This is especially the condition in making a naphtha soap, in which is incorporated naphtha, which is very volatile and some of the well known manufacturers of this class of soap have adopted this process entirely. A laundry soap containing rosin cannot be advantageously made by the cold process, as the soap thus made grains during saponification and drops a portion of the lye and filling materials. By making a semi-boiled soap this objection is overcome. The half boiled process differs from the cold process by uniting the fats and alkalis at a higher temperature.

To carry out this process the following formulae have been found by experience to give satisfactory results.

I.lbs.
Tallow100
Rosin60
Soda Lye, 36° B.80
II.
Tallow100
Rosin60
Silicate of Soda25
Soda Lye, 36° B.85
III.
Tallow100
Rosin100
Lye, 36° B.105
Silicate of Soda25
Sal Soda Solution20

In any of these formulas the sodium silicate (40° B.) may be increased to the same proportion as the fats used. By so doing, however, twenty pounds of 36° B. lye must be added for every hundred pounds of silicate additional to that indicated or in other words, for every pound of silicate added 20 per cent. by weight of 36° B. lye must be put into the mixture. The rosin may also be replaced by a previously made rosin soap.

To make a semi-boiled soap, using any of the above formulae, first melt the rosin with all or part of the fat, as rosin when melted alone readily decomposes. When the mixture is at 150° F. run it into the crutcher and add the lye. Turn on sufficient dry steam to keep the temperature of the soap at about 150° F. in the winter or 130° F. in summer. After the mass has been mixed for half an hour, by continuously crutching the soap it will at first thicken, then grain and it may again become thick before it becomes smooth. When the mass is perfectly smooth and homogeneous drop into a frame and crutch in the frame by hand to prevent streaking. After standing the required length of time the soap is finished into cakes as usual.