From the Manual on Theory and Practice of Beauty Culture 1939:
11. For what purposes are face powders used?
Face powders are used to improve the appearance of the skin; they are also beneficial in soothing an irritated surface and in affording protection against the drying and roughening effects of the weather.
12. How do powders produce a cooling effect on the skin?
A layer of powder dusted lightly over the skin aids evaporation by increasing the area over which the perspiration is spread and thus produces a cooling feeling.
13. Name some ingredients used in making face powders.
Face powders are usually composed of some of the following harmless ingredients: talcum, starches (corn, rice and potato), orris root powder, bismuth salts, magnesium silicate or carbonate, French chalk, perfumes. Stearates, kaolin, etc., are used for their adhesive properties; zinc oxide is used to give weight and body.
14. How is the fine texture of face powder accomplished?
By sifting it through a bolting cloth, usually of silk, after it has been ground.
15. How are face powders made heavy and adhesive?
So called “cold cream” powders are mixed with oil to make them heavy and adhesive; a type of powder that should not be used on an oily skin.
16. What is the best weight of powder for a normal skin?
A medium weight powder made of the proper ingredients is the best for a normal skin. In the cheaper grades of powders, the starches used are likely to form a paste on the skin, and the cheap perfumes used for scent may irritate it.
17. For what purposes are toilet powders used?
Toilet powders are used after the bath and after shaving, and to relieve irritated surfaces.
18. What substances are commonly used for toilet powder bade, and which is best?
Toilet powders usually have a corn starch, talcum or rice powder base. Talcum is the most satisfactory base for a toilet powder as it is not absorbent and is not affected by moisture. The vegetable powders, such as rice and corn starch, are likely to decompose when applied to the skin after the bath.
19. How are liquid powders made?
They are made by combining a whitening substance with a liquid, which then applied to the skin, leaves a deposit resembling a white wash. All traces should be wiped away before retiring for the night.
20. How are compact powders made?
Mucilage or some similar substance is used to bind the ingredients together. the paste is dried in molds to fit the various compacts for which it is made.