September 3, 2013 by thesoapalchemist
In 2009, I decided to coin a new word: Dermathetics.
I defined a dermathetic as a “Soap Additive that is used to contribute skin sympathetic attributes.” Dermathetics add wonderful, skin-benefitting qualities to your soaps but may also provide natural colors, soft fragrances and exfoliating ability. For the natural soapmaker, the most commonly used dermathetics are herbs.
Herbs can be added to soap in many ways. If you do not wish to contribute any exfoliating properties to your soap, but are only interested in the active compounds in your herbs or in the color the herb will lend to the natural soap, it is recommended that you use an infusion of the plant in oil.
Select one of the oils that will be used in your soap recipe. Weigh out the appropriate amount in a mason jar. I generally add about 1 t. to 3 T. herbs per pound of oils in the total recipe, depending on the depth of color I’m aiming for. Allow the mixture to sit for a week or more. The resulting herb-infused oil can be mixed with the other oils in your recipe when you’re ready to make soap. Try using tomato powder to lend powerful antioxidants and an orange color to your soap. Rosemary powder also adds antioxidants, but yields a light beige to camel colored natural soap with lovely speckles.
Herbs can also be used in powdered form and added at trace during the soapmaking process. Some powdered herbs, such as pulverized thyme, are notorious for clumping in soap batter. For herbs that are prone to this, first make a slurry of the powder with glycerin or a bit of an oil you’ve already weighed out for your recipe. Make your slurry with about a 1 to 1 ratio, adding more liquid as necessary to break up the clumps into a homogenous mixture. Then, simply add the slurry at trace.
Another fun way to use herbal dermathetics is to lend exfoliating qualities to your natural soap. In this case, you’ll be adding crushed dried leaves, flowers or seeds at trace. The only real considerations here are aesthetic, and how much exfoliating power you’re interested in. Blueberry seeds are wonderful little natural exfoliators, and can be added with no preparation during trace. Try a rate of 1t-1T. per 5 lb. batch of soap. Course flakes of herbs on the other hand, do not always feel good rubbing against the skin, and for that reason, I like to grind most dried herb leaves in my food processor to reduce the size a bit. It’s really a matter of personal preference. I like to be able to see the herbs in my soap, but I don’t want them to give me splinters! Be particularly careful if your dried herbs contain stems, as these can be especially sharp and hard.
For a pretty touch, whole flowers can be added to soap batter in the same way. While the colors and fragrances won’t necessarily survive saponification, I’ve found that lavender buds and chopped chamomile flowers, can impart a bit of their natural fragrance to my finished soap, along with muted variations of their original colors. Natural Bar Soap Company’s Devotion Soap and Vincent’s Voyage Soap both use flowers for a bit of natural scent and color, as well as a fun, scrubby texture.