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Powdered Soaps.
In this form very convenient kinds of cosmetics are made and used for a variety of purposes, as a dentifrice, for shaving, etc. They are made from any pure soap, which is cut into shavings and thoroughly dried, when they are ground and sieved into the finest possible powder, perfumed and colored in any way desired. They should be put up in well-stopped bottles, or they will absorb moisture and form into lumps again. --TECHNICAL TREATISE ON SOAP AND CANDLES, Richard S Cristiani, 1888.
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Shaving soap powders are made as follows: First prepare a good shaving soap in the warm way from, for instance, 500 lbs. of tallow and 100 lbs. of cocoanut oil. Boil the fats with equal parts of caustic soda lye of 25 degrees B. and caustic potash lye of 25 degrees B. to a clear paste and separate the soap with brine. The settled grain is brought into frames and when cold, is cut into bars which are converted into shavings. The latter are thoroughly dried and ground to a fine powder in a mill.
This powder is mixed with starch in the proportion of 15 to 20 lbs. of the latter to 100 lbs. of the former. By the addition of starch to the soap powder, a shaving powder is obtained which gives a fine permanent lather.
Before mixing the starch with the soap powder it is perfumed, as a rule, with a mixture of lavender oil, thyme oil, caraway oil and fennel oil, an agreeable perfume being composed as follows: Starch 30 lbs., lavender oil 2^ ozs., lemon oil and thyme oil each 1\ ozs. The starch and perfume are intimately mixed and the whole is passed through a sieve which, however, should not be too fine. If the perfume is added to the powdered soap it forms small balls which in spite of all trouble cannot be entirely got rid of and finally remain behind upon the sieve.
A very fine shaving powder with a very durable and pleasant odor is obtained by a mixture of powdered soap 50 lbs., powdered orris root 8 lbs., and almond paste 4 lbs. The whole is intimately mixed and then passed through a sieve. --Soap Maker's Handbook, C Diete, 1912
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SHAVING SOAPS.
The requirements of a shaving soap are somewhat different than those of other soaps. To be a good shaving soap the lather produced therefrom must be heavy, creamy, but not gummy, and remain moist when formed on the face. The soap itself should be of a soft consistency so as to readily adhere to the face when used in stick form. It should furthermore be neutral or nearly so to prevent the alkali from smarting during shaving.
Shaving soap is made in the form of a stick, and a tablet for use in the shaving mug. Some shavers prefer to have the soap as a powder or cream, which are claimed to be more convenient methods of shaving. While a liquid shaving soap is not as well known because it has not yet become popular, some soap for shaving is made in this form.
Formerly shaving soap was extensively made from a charge of about 80 parts tallow and 20 parts cocoanut oil as a boiled settled soap, but either making the strengthening change with potash lye or using potash lye in saponifying the stock and graining with salt. [In other words, the soap was made with NaOH and KOH or the soap was a KOH soap that was partly converted to sodium soap by using salt.] Soaps for shaving made in this manner are very unsatisfactory, as they do not produce a sufficiently thick or lasting lather and discolor very materially upon ageing. Potassium stearate forms an ideal lather for shaving, but readily hardens and hence needs some of the softer oils, or glycerine incorporated with it to form a satisfactory soap for shaving.
The selection of materials for making a shaving soap is important. The tallow used should be white and of high titer. Cochin cocoanut oil is to be preferred to the other kinds, and the alkalis should be the best for technical use that can be purchased.... By the use of stearic acid it is a simple matter to reach the neutral point which can be carefully approximated....
SHAVING POWDER.
Shaving powder differs from the soaps just described in being pulverized, usually adding up to 5 per cent. starch to prevent caking. Any of the above soaps, dried bone dry, with or without the addition of tallow base make a satisfactory powder for shaving. --Soap Making Manual, E G Thomssen, 1922.