There are many botanical ingredients you can use as cold process soap ingredients. Lavender and rose petals are classics, and Himalayan Pink Salt soaps are trendy and inviting. Adding fruit and vegetable purees to cold process soap is one method of using your garden produce to create something unique. Purees add both color and variety to your soaps. It is not known whether any of the skin-loving properties of the produce will survive the soap making environment, but there is just something extra appealing about a blueberry scented soap filled with fresh blueberry puree.
You can use any kind of fruit or vegetable puree in your soap. If you can create a smooth consistency, you can add it to your cold process soap. However, adding purees to soap batter should be considered an advanced soapmaking technique – there are many variables to consider. It is best that you have several successful soap-making sessions under your belt before experimenting with purees.
Purees add fats, natural sugars, sodium and water to your soap. Each different puree will have a different effect on your finished soap. The amount of fat, sugar, sodium and water will vary depending on the ingredient. A strawberry puree will add significant sugar and water. An avocado puree will add extra fats, sodium and water, but little sugar. A tomato puree adds mostly water, sodium, and a very small amount of sugar.
Most purees are made by adding ingredients into a blender or food processor and blending until as smooth as possible. Straining the puree is also a good idea to avoid large pieces in the soap which could spoil. Bear in mind that some ingredients may need a small amount of added water to achieve a smooth texture. It is for this reason that when using a puree in your soap, I strongly recommend using a water discount. A water discount means withholding a small portion of the total water used in the recipe. Fruits and vegetables contain water. If you’re adding produce plus extra water to make a puree, all that water can throw your recipe off. Too much water is not dangerous to your recipe, but it increases the chances of soap crackling, or glycerin rivers – a harmless, cosmetic phenomenon. It will also increase the amount of time your soaps require to fully cure.
Adding too much puree can throw off the balance of oils and lye for soap. In the worst case, adding too much puree could cause mold and bacteria growth in the soap. A usage rate of about 1 ounce of puree per pound of oils in the soap recipe is considered a universally safe amount. The pH level of cold process soap does not allow for mold and bacteria to grow, as long as the soap is not diluted too much. However, DOS (dreaded orange spots) can occur if the oils in the bar become rancid due to too much moisture. These spots are a cosmetic flaw, however, the soap is perfectly safe to use.
The best time to add your puree is at thin trace. This makes it easier to blend with a stick blender or whisk. If the puree contains a lot of natural sugar, expect it to speed up trace. If the puree contains little to no sugar, expect it to thicken trace only a little, if at all. Adding sugar-containing purees to cold process soap not only speeds up trace, it also increases temperature. Higher temperatures increase the chance of the soap going through gel phase. This refers to a part of the soap making process where the soap gets warm and gel-like – with temperatures rising up to 180 degrees. Gel phase is not harmful to soap, but soap can also “volcano” when it becomes too hot. If the puree contains a lot of sugar, I recommend working at room temperature or colder and placing the soap into the refrigerator or freezer after pouring into the mold to help it stay cool and opaque.
A word about using baby food purees in soap: be careful. Make sure to read the ingredients and ensure there are no additives beyond the produce and water for processing. Thickeners, salt and sugars in the purees can throw off your results easily. Also, be sure to avoid fermented fruits, such as black bananas and fruits with soft spots. The extra high sugar content can affect results, as can any natural alcohol content in the fruit.
Once again, I highly recommend doing several successful cold process soap recipes before adding purees to your soap. The purees can affect every stage of the soaping process from recipe to cure time. The experimentation can be loads of fun, however, and a way of coloring soap naturally. Imagine a soap containing fresh tomato puree, scented with a tomato leaf fragrance oil. Or a green avocado soap with rosemary essential oil. Pumpkin is another pureed favorite that lends a gorgeous orange color to the finished soap. Try adding orange and clove essential oils to a pumpkin soap for a wonderful fall fragrance.
Have you tried adding produce purees to your soap ingredients? What is your favorite puree to add?