There's something satisfying about a bar of soap that gets its color from the garden or the spice cabinet instead of a bottle. Natural colorants are a little less predictable than micas and dyes, and that's half the fun. Here's how to color homemade soap naturally, which ingredients give which colors, and what to expect when they meet lye.
A word about lye
Cold process soap batter is strongly alkaline for its first day or two, and that changes a lot of natural colors. Some survive beautifully. Others shift, fade or turn an unexpected brown. Beet powder is the classic heartbreak. It goes into the pot a gorgeous pink and comes out a dull tan. So test small batches before you commit a whole loaf, and keep notes.
Natural colorants and the colors they give
- Yellow to orange. Turmeric gives warm yellow to gold, and a little goes a long way. Annatto seed, infused in oil, gives yellow to deep orange. Paprika gives a soft peach to orange.
- Pink to red. Rose clay gives soft pinks. Madder root gives pinks through rusty reds, depending on how much you use.
- Purple to blue. Alkanet root, infused in oil, gives purples that drift toward blue-gray. Indigo powder gives blues, from pale to deep.
- Green. French green clay gives a soft sage. Spirulina and other green powders give brighter greens that tend to fade over time.
- Brown. Cocoa powder, coffee and cinnamon all give browns. Go easy on the spices, which can be scratchy in larger amounts.
- Gray to black. Activated charcoal gives anything from light gray to true black.
- White. Kaolin clay gives a soft, creamy white.
Three ways to add natural color
Infuse it in oil. Steep roots or seeds like annatto, alkanet or madder in some of your recipe's oil for a few days (or gently warm it for an hour), then strain and use that oil in your batch. This gives the smoothest, most even color with no specks.
Mix it with a little oil and add at trace. Stir clays, cocoa, charcoal or spice powders into a spoonful of oil to break up the clumps, then blend that into your batter at light trace. This is the easiest method, and the most common.
Add it to the lye water. Some colorants, like madder root and some clays, can go straight into the water before you add the lye. Do this only with colorants you've read up on, since a few react oddly at that stage.
How much to use
Start small. A common starting point is about half a teaspoon to a teaspoon of powder per pound of oils, then adjust in later batches. Strong colorants like charcoal, indigo and turmeric need very little. Clays can take more. Using too much of some colorants can tint the lather, which is a sign to dial it back.
Our recipe scaler makes it easy to try the same recipe in small test batches.
Tips for better natural color
- Keep your batter cooler. Some colors, especially greens, hold up better when the soap doesn't overheat.
- Expect fading. Plant-based colors often soften over weeks in the light. Cure and store bars out of direct sunlight.
- Combine colors in swirls and layers. Natural colorants look wonderful side by side, like a turmeric layer on a charcoal base.
- Write everything down. Natural ingredients vary from batch to batch, so your notes are your best recipe.
Where to go next
If you're new to soapmaking, start with our beginner's guide on how to make soap, and use the lye calculator for every batch. For more about one of the warmest colorants, we wrote about turmeric soap. And if you'd like to see how a professional bar turns out, the whole soap shelf is here.