LIGHT OR FLUFFY POWDERS.
Light or fluffy powders containing 35-45% moisture can be made in two ways. The first method requiring a minimum equipment is to mix the powder and sal soda in a mixer, allow it to stand in frames for a week to crystallize or spread it on the floor for a few hours to dry and then grinding it.
The continuous method finishes the powder in a few minutes and with a minimum amount of labor. By this process the various ingredients, soap, soda ash solution, etc., are measured, run by gravity into the mixer, mixed and the molten mass run over the crystallizer or chilling rolls thru which either cold water or brine is pumped. From the roll the powder is scraped off clean by a knife, passes to a screen which sends the tailings to a grinder, falls into a storage bin from whence it is weighed and packed by an automatic weighing machine into cartons made up in most cases by another machine. Due to the large percentage of moisture contained in these soap powders the carton is generally wrapped in wax paper to aid in the prevention of the escape of moisture.
Scouring Powders.
Scouring powders are very similar to soap powders and differ only in the filler used. We have already considered these fillers under scouring soap, from which they do not differ materially. They are usually insoluble in water to aid in scouring. The mixer used for substances of this kind in incorporating the soap and alkali must be of strong construction.
SCOURING SOAP.
Scouring soaps resemble soap powders very closely in their composition, in that they are a combination of soap and filling material. Since more lather is required from a scouring soap than in soap powders, a cocoanut oil soap is generally used. The usual filling material used is silex. The greatest difficulty in the manufacture of scouring soap is the cracking of the finished cake. This is usually due to the incorporation of too great an amount of filler, or too high a percentage of moisture.
In manufacturing these soaps the cocoanut oil is saponified in the crutcher with 38 degs. B. lye, or previously saponified as a run soap, as already described under "Marine Soaps." To twenty-five parts of soap are added a percentage of 38 degs. B. sal soda or soda ash solution, together with a small quantity of salt brine. To this mixture in the crutcher seventy-five parts of silex are then added, and a sufficient amount of hot water to make the mass flow readily. Care must be exercised to not add too great a quantity of water or the mass will crack when it cools. The mass is then framed and cut before it sets, or poured into molds and allowed to set. While silex is the most extensively used filler for scouring soaps, it is feasible to incorporate other substances of like character, although it is to be remembered that the consumer is accustomed to a white cake, such as silex produces. Any other material used to replace silex should also be as fine as this product.
FLOATING SOAP.
Floating soap occupies a position midway between laundry and toilet soap. Since it is not highly perfumed and a large piece of soap may be purchased for small cost, as is the case with laundry soap, it is readily adaptable to general household use. Floating soap differs from ordinary soap in having air crutched into it which causes the soap to float in water. This is often advantageous, especially as a bath soap, and undoubtedly the largest selling brand of soap on the American market today is a floating soap.