Nature provides us with beautiful colors that can be applied to coloring soap. You can add plant material directly to the soap mixture to create not only color but texture as well. Most plant material that starts out green will eventually turn brown. However, some botanicals — calendula petals, for example — retain their color when added at the end of the process. You can also use dried herbs in hand-milling products if you really want the color to stay for a while. Be sure that when you're adding herbal ingredients directly into the soap that you remove sticks, twigs, and other sharp parts of the plant.

To get the color from the plant matter into your soap, you can use a variety of methods. Infusing oil and water with a high concentration of the color herb creates a usable dye. Be sure to record the amounts, temperatures, and length of infusion time so you can repeat what works. There are a few commercially available plant dyes. TKB Trading makes a small range of natural plant gel colors.

There are quite a few plants that work as colorants for soap, but annatto seed and alkanet root are some of the most easily used. Since plants vary from season to season and crop to crop, you should test each new supply you purchase. The following two exercises in making your own natural dyes will start you on your way to further experimentation. For these recipes, use two heatproof clear containers that will hold at least two cups.

You can now experiment with the alkanet oil and annatto water and oil. Keep track of the concentrations and the amounts you add to each application. Take notes on how they perform in each soap technique. Use this same experiment to expand your plant-based colorant vocabulary.