One of the fun parts of making your own soaps and bath/beauty products is getting to experiment with additives. Many crafters particularly enjoy using natural colorants and additives, to create a more natural product than is commonly available on the commercial markets. Two fun additives that you might want to try are turmeric and calendula, made from plant roots and flower petals respectively, for beautiful natural shades of yellow and the skin soothing benefits of calendula. Here is some more information on them:
Turmeric - Turmeric is a spice commonly used in curries and other South Asian and Middle Eastern dishes. It has a distinctly earthy, somewhat bitter, and slightly hot peppery taste, coupled with a mustardy smell. Turmeric powder is manufactured by boiling turmeric roots for several hours and then drying them in hot ovens before grinding them into a powder. In addition to being used in food, turmeric is used in dyeing fiber and as a commercial colorant in foods such as mustard, cheese, butter, and salad dressing. In CP soap, the turmeric powder will at first turn the soap a vibrant orange-red when added to soap at trace. It then mellows to a creamy tan (with the occasional brown fleck) once the soap has firmed enough to remove from the mold (about 24 hours later). The turmeric powder will also give it a slightly spicy scent. The maximum usage rate should be about 2 teaspoons of turmeric per pound of fat/oil. In melt and pour soap, turmeric will turn the soap a muted yellow/tan, and about one teaspoon per pound of soap base is a good ratio.
Calendula Powder - Calendula powder is a wonderful addition to not only CP and MP soaps, but to other bath products as well, such as lotions, massage oils, body butters and balms. Calendula has been used in baby products and skin products for years, as it is renowned for its skin soothing properties. It also is one of the very few botanicals that will hold its cheerful yellow color in soap (most other botanicals turn brown or black) and it has a lovely, wholesome and calming nutty/oatmeal, milk and honey type of a scent.
Lots of people add calendula (whole petals or powder) to CP and MP soap for decoration. A little goes a long way, and make sure to stir them thoroughly into your soap so you don't get "clumps". To get more of the properties and scent of calendula into your product without having to use whole calendula, it's best to infuse the powder into oil. Put a bunch of calendula powder in a muslin bag, tie it tightly and put it in a glass jar. Then pour enough oil to cover the bag, plus about an additional inch over it. (Make sure the bag is fully submerged in the oil).
Tightly cap the jar and put it in a cool, dark location for a couple of weeks. Take it out every day or so and shake it to make sure that the whole bag of powder is thoroughly coated in oil. After two weeks, pull out the bag and use your infused oils in balms, body butters, lotions, etc. - or as an additive in MP soap - or in the oil portion of a CP soap. The oil soaked calendula powder can still be added to soap, or used in a facial mask; it will mix particularly well with clay or oatmeal for a skin-soothing mask.
You can also "heat infuse" the calendula into oil by putting the powder - sealed in a muslin bag - into oil and heating the mixture gently for an hour or so. (A crock pot is ideal for this purpose!) Then pull the muslin bag out and use the resulting oil in your recipes. Please note that the heating process can harm the antioxidants in your oil, resulting in an oil that goes rancid more rapidly than a cold infused oil.