Charcoal in Soap: Usage Rates & Tips

Learn how to use charcoal in soap, how much charcoal you need to make gray and black soaps, plus a helpful usage rate table for reference!

wooden board with multiple heart shaped soaps

Activated charcoal is a popular natural ingredient to include in soap and other skin care products, because of its power to draw impurities from your skin.

(This same action that makes charcoal good for your skin, makes it a useful addition to Black Drawing Salve – which is helpful for splinters, boils, and insect bites.)

What exactly is activated charcoal?

Activated charcoal is a very fine dark black powder that’s produced by processing carbon-rich items such as bamboo, coal, or coconut shells at high temperatures.

That high heat treatment changes its structure and creates an expansive sponge-like surface area, which is what makes it have such tremendous absorbing capabilities.

It can be used internally to absorb toxins and flush them from your body, and is even used for some types of poisoning or drug overdoses.

Activated charcoal is also used externally in skin care products. It’s especially nice for oily or acne-prone skin, though all skin types can use it.

(Important note: Activated charcoal is not the same kind of charcoal that you use for grilling and backyard barbecues, so don’t crush up a briquette and add to your soap.) 😊

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two rows of charcoal in soap results

How much charcoal do you put in cold process soap?

Besides its potential skin benefits, activated charcoal also looks nice in soap, turning it anywhere from gray to black, depending on how much you use.

Over the years, I’ve gotten several requests about how much charcoal to use in cold process soap, so decided to mix up some sample batches and create this handy table to use as a guideline.

Keep in mind that the recipe you use, plus the brand of charcoal, may produce slightly different shades for you.

These samples were made with: 56% olive oil, 25% coconut oil, 13% shea butter, 6% castor oil, with a 5% superfat, and a 2 to 1 water: lye ratio. Brand of charcoal used: Bramble Berry.

Whether your soaps go through gel phase or not can also affect the color. Gel phase usually enhances and darkens natural colorants. (These sample soaps shown did not go through gel phase.)

Use this information as a starting guideline, knowing that you may need to tweak amounts depending on your recipe.

Amount of charcoal to use per pound of oils (PPO):

1/8 tsp PPOlight gray soapwhite lather
1/4 tsp PPOmedium gray soapwhite lather
1/2 tsp PPOmedium gray soapwhite lather
1 tsp PPOdark gray soapfaint gray lather
1 1/3 tsp PPOdark gray soaplight gray lather
2 tsp PPOgray-black soaplight gray lather
1 TBSP PPOblack soapnoticeably gray lather
4 tsp PPOblack soapdarker gray lather

What does PPO mean?

PPO stands for Per Pound of Oils in a recipe.

There are 16 ounces (weight, not volume) or 454 grams in a pound of oil.

So if you want to use charcoal at 1/2 tsp PPO, that means that you would add 1/2 teaspoon of charcoal for every 16 ounces or 454 grams in the recipe.

If the recipe has 16 ounces of oil in it, you would use 1/2 teaspoon of charcoal.

If the recipe has 32 ounces of oil, you would use 1 teaspoon of charcoal.

Most of my recipes have 28 ounces of oil (1 3/4 pound), so you could either round up and calculate as though it has 2 pounds of oil (and get a slightly darker soap), or you could do some math and divide down how many teaspoons for every 4 ounces of oil.

1/2 teaspoon per pound (16 ounces) of oil can be broken down into:

1/4 teaspoon per 8 ounces of oil

1/8 teaspoon per 4 ounces of oil

Using that information, you would see that the recipe with 28 ounces of oil would need 7/8 teaspoon of charcoal to equal the same rate as 1/2 tsp PPO.

two stacked round soaps made with charcoal

When do I add charcoal to soap?

If you’re making a solid colored soap, just add the charcoal to your warmed oils and blend with your stick blender (immersion blender), right before adding the cooled lye solution.

Some soapers like to instead add charcoal to the soap batter at emulsification or when it reaches a very light trace, then use a stick blender to blend it in thoroughly.

If you’re making a charcoal swirl within a different colored soap, you can mix the charcoal with a small amount of oil from the recipe and then blend into a portion of soap batter.

Or, what I normally do instead is mix the charcoal with a small amount of glycerin until it forms a smooth paste, then mix into the portion of soap batter that will be swirled in.

Does it matter if the soap’s lather is gray?

Most people don’t mind that the lather of charcoal soap is often gray, especially if you explain to them up front, that it’s the nature of the soap.

If gray lather bothers you, then just use less activated charcoal for a lighter colored soap and lather.

Black charcoal soap can leave dark marks on your soap dish and washcloths. These will wash out and shouldn’t stain, but you can always reduce the amount of charcoal in the recipe to reduce the chance of this happening.

Does charcoal make your soap softer?

Some soapmakers feel that charcoal makes their soap softer and that it takes longer to firm up in the mold.

If this happens to you, try reducing the amount of water used in your recipe.

If you normally use a full amount of water, try using a 2:1 water to lye ratio instead.

This means that you would use twice as much water as lye. (If your recipe calls for 4 ounces of lye, then use 8 ounces of water.)

You can also add sodium lactate to the cooled lye solution at a rate of 1 teaspoon PPO (per pound of oil in the recipe) to harden soap.

Charcoal Cleanup Tips

Working with charcoal is messy!

The fine powder seems to get everywhere and easily smears across dry surfaces and your hands.

Try these tips for an easier cleanup time:

  • Place a sheet of wax paper or a paper towel under the area that you’re working at to catch any charcoal sprinkles and spills.
  • After using the measuring spoon, first wipe the charcoal off of it with a dry paper towel, and then wash it with soap and warm water. This keeps the charcoal from sticking to the spoon.
  • Use dish soap and warm water to soak and then thoroughly wash all charcoal containing dishes and utensils.
  • Charcoal can usually be washed off your hands with soap and water, but if some sticks around, try rubbing coconut oil or a rich hand cream into your skin, then washing again with soap and water.
tall stack of round charcoal soaps on a wooden background, text says "Charcoal in Soap, Usage Rates & Tips"
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  1. Beautiful post (as always). Planning to make a soap colored with only activated charcoal in different proportions. Thanks Jan!!!

    1. Hi Jeannine, Yes, you sure can! To add charcoal to melt and pour soap, dilute it with about 3 times as much isopropyl (rubbing) alcohol, then stir into melted soap base. So for 1/2 teaspoon charcoal, you would mix it with 1 1/2 teaspoon alcohol. To keep the charcoal suspended in the soap, let the melted soap/charcoal mixture cool to under 135 degrees F (57C) before pouring. I plan to do a post just like this, only for different rates of charcoal + melt and pour in the future on my other website – where you can also see how I use charcoal to make pencil lines in melt and pour soap:

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