With the explosive growth of natural and organic soaps, makers are always looking for something new or innovative to differentiate their products. A common practice is the addition of plant material.
Soap with real lavender buds on top, loose oatmeal, and dried plant matter are rather common and can be found at most festivals and craft shows. Few makers use real plant matter in the body of a soap. It is a challenge and the risk of spoilage can be high if certain precautions are not taken.
Water is the problem. Water is the birthplace for bacteria and opens the door to spoilage. Live plant matter contains water. So in terms of flower petals, coffee grounds and other plants incorporated for an exfoliating effect, the additions must be BONE dry. Live petals, needles, seeds etc. contain water and will allow rot to start inside the soap. Preservatives do not solve the problem and are problematic in many other ways. We don’t want synthetics in “natural” soap. If made properly, no preservatives are needed in soap. Proper cure time is critical for all cold process soap.
For the addition of purees, calculation of actual water content of the puree is needed or at the very least, taking the time to research how much water the puree typically carries. Then the water content of the lye portion should be reduced by approximately the same amount. This is basically the same as a “water discount” or reducing the amount of water in the recipe to encourage the soap to cure faster. Fortunately, it takes very little puree to enhance the conditioning effect of a soap.
In addition to the goat milk, we use avocado puree and pumpkin puree in specific bars. It takes these bars at least 25% longer to cure due to the addition.
An easier way to introduce special conditioning without risking deterioration of a puree, is to use teas or infusions. These can be quite powerful in terms of anti-oxidant benefits and help reduce inflammation. Green tea, blueberry juice and other fruits, coffee, cucumber water, celery water, and other water based botanicals can assume the water portion of the lye without issue.
Before adding anything “new” to soap, the maker needs to test the ingredient in an actual test batch. Longevity of the soap needs testing as well and hardness over time as there will be variance as compared to a water based soap. Botanicals offer wonderful benefits provided they are incorporated carefully with proper calculations.