Activated charcoal
Light grey to deep black. Fisher, The Complete Photo Guide to Soap Making primary source
Opens the calculator’s starter recipe, 1000 g of oils, with this additive at the dose it fills in, ready to change.
What it is
Activated charcoal is a carbon powder made in food and medical grades; MakingCosmetics sells a USP grade for cosmetics.
UES; Norit primary source
How much
- 0.25 tsp per pound of soap filled in (from the source’s dispersion: a teaspoon of powder in a tablespoon of liquid) Soap Queen supplier or guide
- 1 tsp per pound of soap Cable, The Natural Soap Making Book for Beginners primary source
- 2 tsp per pound of oils Fisher, The Complete Photo Guide to Soap Making primary source
- 0.57–1.71 tsp per pound of soap in melt and pour or rebatch (from a published recipe that adds it to one part of the batch: the lower figure over the whole batch, the higher within that part) Fisher, The Complete Photo Guide to Soap Making primary source
- up to 3 % of the batch in rinse-off products, the highest reported use: not a recommendation CIR primary source
The calculator fills in 0.25 tsp per pound of soap: 1.7 g for the 1000 g of oils in its starter recipe.
When and how
- Usually: at light trace.
- Mix it first with a little of the recipe’s oil, about a teaspoon of powder to a tablespoon of oil, so it spreads without specks.
Bramble Berry supplier or guide
What it does to the recipe
- It changes neither the lye nor the water: it is only weight in the bar.
Worth knowing
- Too much colours the lather. Soap Queen supplier or guide
- In the EU soap is a cosmetic, and may be coloured only with the colourants in Annex IV of the Cosmetics Regulation. In the US the colour additives allowed in cosmetics do not include this one; a true soap sold as soap alone is not a cosmetic there. Regulation (EC) No 1223/2009; 21 CFR 73 primary source
Spoons and drops
- 1 tsp ≈ 2.22 g (1.73–2.71 g)
- 1 tbsp ≈ 6.65 g (5.18–8.13 g)
- 1 cup ≈ 106 g (82.8–130 g)
UES; Norit primary source
INCI name
Charcoal Powder
- CAS number
- 16291-96-6, 7440-44-0
- EC number
- 240-383-3
Recipes that use it
Guides that discuss it
Sources
David Fisher, The Complete Photo Guide to Soap Making (Creative Publishing International, 2018), p. 20: dyes "give a full range of hues—from subtle to bright and bold", but "can bleed between layers or swirls of soap, especially in melt-and-pour soap. Some are not stable in cold process soap, so test them first"; oxides "are very stable and strong in soap". Natural colours, pp. 82–84. In an infused oil: "Annatto: yellow-orange"; "Alkanet: light to deep purple, depending on the amount used"; "Paprika: orange-peach". In the lye solution: "Indigo: light to deep blue"; "Madder root: pinkish-red"; "Rose clay: deep rose pink". Added to the oils or at trace: "Activated charcoal: light gray to deep black"; "Black walnut hull (ground): speckled brown, also an exfoliant"; "Calendula flower petals (whole or ground): nice, warm yellow"; "Carrots (puréed or juiced): muted orange"; "Cinnamon: reddish tan to brown"; "Cocoa powder: tan to brown"; "Cucumber: pale yellow-green"; "Rosehips (ground): speckled reddish brown"; "Sage: muted green"; "Spirulina: pastel green/blue-green". For "a bright, white bar of soap": "Add titanium dioxide: about 1 teaspoon per 1 pound (454 g) of oils."
Bramble Berry, activated charcoal: mix "1 teaspoon of the powder with 1 tablespoon of a lightweight oil".
Soap Queen, activated charcoal: "1 teaspoon of dispersed charcoal per pound of soap"; "Charcoal can create a gray lather".
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).
Cosmetic Ingredient Review, charcoal (2023): charcoal powder up to 3 % in bath soaps and detergents.
The highest concentration reported to CIR in industry surveys: what has been used, not a recommendation.
EU: Regulation (EC) No 1223/2009, Article 14(1)(c), a product may contain as colourants only those in Annex IV. US: 21 CFR Part 73 Subpart C lists the colour additives for cosmetics, and turmeric, paprika and spirulina are listed for food only; under 21 CFR 701.20 a true soap, sold only as soap, is not a cosmetic.
Food and medical activated carbons: UES MD, packing density 0.46 g/cm³ (2025); Norit CN1, tamped 370 kg/m³; charcoal powder USP (MakingCosmetics), 0.45–0.55 g/mL.