Kaolin clay

Kelly Cable, The Natural Soap Making Book for Beginners (Althea Press, 2017), chapter 4: "I prefer to use white kaolin in small amounts for a silky soap, as too much will make soap slimy"; turmeric, "when it is added as a powder at trace it will give your soap a strong golden-orange color that will fade significantly after curing to a pretty but more muted gold".

Bramble Berry, clay in bath and beauty projects: clay "dispersed in distilled water ... 1:3 ratio of clay to liquid".

Lovin Soap, soapmaking additive chart: clay 1 teaspoon, oatmeal, coffee grounds and cocoa 1 tablespoon per pound of oils; cocoa into the warm oils; silk, "1 pea size pinch per pound of soapmaking oils".

Kelly Cable, The Natural Soap Making Book for Beginners (Althea Press, 2017): "Replacing 25 percent of the water with juice gives the bar a more golden color without browning or causing sugar difficulties"; most juices "turn a dark color within the soap, typically brown"; juices frozen "to a slush" before the lye; "when adding purées, always remove the same weight in water"; 2 ounces of puréed strawberries at light trace for 33 oz of oils, all of it in half of the batch, where "the sugars from the purée can cause this soap to possibly overheat"; "Beet root powder starts off a pretty, bright pink, but when added to soap, it turns brown"; "most herbs turn brown when added at trace. If you want to avoid this, add them to the top of your soap right before it sets"; "Make sure your herbs are very dry before adding them to the soap, as moisture left within herbs can bleed into the soap over time, leaving a brown halo". "Green can be made with spirulina, comfrey leaf, and parsley leaf". Activated charcoal: "Add 1 teaspoon per pound of soap". Recipes, per 31–35 oz of oils: "2 tablespoons ground turmeric" blended into the whole batch (32 oz), and "3 teaspoons ground turmeric" in one of four equal parts (31 oz); "2 teaspoons woad powder" and "1 tablespoon white kaolin clay", each in one of three equal parts (34 oz); 1 tablespoon of dried nettle leaf, or 2 tablespoons; 1 tablespoon of ground cinnamon; 1 tablespoon of dried peppermint flakes, "plus more to sprinkle on top"; 1 tablespoon of steeped chamomile flowers at light trace and 2 on top; comfrey, "1 heaping tablespoon comfrey leaf powder" infused in 8 ounces of olive oil, 3 ounces of that oil in the recipe.

David Fisher, The Complete Photo Guide to Soap Making (Creative Publishing International, 2018): rebatched soaps, "1 tablespoon (6 g) red sandalwood powder" for 1 lb (454 g) of grated soap, and "1 tablespoon (1.5 g) lightly crushed rose petals buds" for a pound (p. 34); "1 to 2 tablespoons (5 to 10 g) ground walnut shells" in one third of 28 oz (794 g) of grated soap (p. 32); "1 tablespoon (9 g) kaolin, bentonite, or French green clay" in another third and "1 teaspoon activated charcoal—a little goes a long way" in the last (p. 32); "2 tablespoons (10 g) lightly ground oatmeal" for 1 lb (454 g) of grated soap (p. 32); in melt and pour, "¼ teaspoon cosmetic glitter" in about 4 ounces (112 g) of clear base (p. 54); in cold process, "2 teaspoons activated charcoal per 1 lb (454 g) of soap oils" (p. 121), and for the three colours of a clay swirl "½ teaspoon rhassoul clay", "½ teaspoon green sea clay" and "½ teaspoon red Moroccan clay", each mixed with 3 tablespoons (45 ml) of distilled water (pp. 121–122).

Susan Miller Cavitch, The Natural Soap Book (Storey Publishing, 1995), chapter 6: clay, "add the clay to your soap just before pouring into molds, using ½ to 1 cup (118 to 237 ml) for a 12-pound (5.45 kg) batch of soap. Before adding the pure essential oils, blend the clay with 2 cups (473 ml) of soap mixture in a small container" (pp. 62–63); "Oatmeal, cornmeal, flax seed meal, juniper berry meal, alfalfa meal, flaked seaweed, and jojoba meal can all be added to soap for texture. Oatmeal, jojoba meal, and alfalfa meal exfoliate gently. Juniper berry, flaked seaweed, and flax seed meals are more coarse, with sharper edges; finely grind them before adding as exfoliants to soap"; "½ to 1 cup (118 to 237 ml) of meal is suggested for a 12-pound (5.45 kg) batch of soap", added "immediately after the soap has saponified" (pp. 66–67). ½–1 cup for 12 pounds is 0.67–1.33 tablespoons per pound of soap.

Cosmetic Ingredient Review, natural clays (2023): kaolin 1–5 %, bentonite 0.22–4.7 % and illite up to 0.34 % in bath soaps and detergents; montmorillonite up to 3 % in rinse-off products.

The highest concentration reported to CIR in industry surveys: what has been used, not a recommendation.

Soap Queen, clay in soap: "clays also speed up trace".

Lovin Soap, clay in cold-process soap: undispersed clay risks "causing cracks or crumbly soap".

Kaolin bulk density: Carl Roth, Bolus alba extra fine, safety data sheet (2024), about 470 kg/m³; purified kaolin as a pharmaceutical excipient, Minerals 10 (2020) 23, Table 2, poured 0.51–0.64 g/mL.