The following article by Kaila Westerman first appeared in the newsletter Creative Alchemy, published by Sunfeather Herbal Soaps. It has been edited slightly to work within this web site.

Introduction

When you start out as a cold process (CP) or Handmilled soapmaker, color is the least of your worries. Color doesn't add to the emolliency, mildness or hardness of the soap, and it rarely adds scent or texture. Perfectly wonderful bars of soap are made every day without consideration to color. However, as your confidence increases, color squeezes into the fore along with everything else.

For the more decorative MP soapmaker, color is extremely important from the get go. Having a broad palette to choose from is essential to the craft.

Eventually, then, all soapmakers benefit from understanding what their options are for adding color, and how those color options work within their medium. The key elements are: Source, and Stability.

Source

Before you even begin to consider what to "add" as a colorant, you must recognize that the first source of color for your soap is your base. A CP or Handmilled soap made from lard, tallow or coconut oil, for example, will be white. Olive oil, on the other hand may produce a greenish soap. Unrefined Palm Kernel Oil results in a yellow soap. The MP soapmaker will start with either a clear soap base, possibly with a yellow tint, or a soap base which has been doctored with Titanium Dioxide (TD) a cosmetic grade colorant to make it pure white. TD is a very "aggressive" whitener and will always turn bright colors into pastels.

The blend of fragrance oils will also effect your soap. I used to make a yellow-colored CP soap by laboriously first steeping annatto seed in the base oils. One day, I didn't have annatto seed but I made the soap anyway. To my surprise, I discovered that the fragrance blend of lemon, lemongrass and orange essential oils (with a hint of anise), made the soap yellow to begin with. In another instance, I once made an MP soap using a grape fragrance. I was shocked at how crystal clear the formerly amber-toned soap became, and quickly attributed it to the amount of alcohol in the fragrance oil.

Some superfatting oils can also be used as colorants. If you superfat any of the soap types with Walnut Oil, for example, the soap will tan slightly. Hemp Seed Oil can add a green tint.

Once you have established the backdrop color of your bar, you may wish to source a colorant additive. There are several options.

Herbs, Spices and Other Plant Materials

Saffron, annatto, turmeric, cinnamon, rosemary, cornmeal, seaweed . . . the variety of "natural plant" ingredients to choose from is endless. Browse your local health food store or ethnic grocer's for ideas. Most natural colorants will keep you in the realm of yellows, greens, and earth-toned reds and browns.

Generally, there are five options when working with natural plant colorants:

1) Add in powdered form at the trace or when the soap is melted (note: to avoid freckles of undissolved color, it is best to suspend the powder in a bit of water before adding it to the mix);

2) Add in whole form (note: obviously, this can add abrasiveness to your bar. It can also result in unattractive bits of herb sticking to the body when you wash, so consider this option with care);

3) Infuse in the base or superfatting oil over low heat and then strain out (note: some soapmakers do not like to overheat their oils for fear of cooking out their nutritive value; instead, you may wish to infuse the oil using a passive method by putting the oils and plant materials in a jar in a sunny window);

4) If you make Cold Process soap, infuse in the water portion of the lye/water mix by simmering the plant material in the water over low heat and then straining out (note: usually, I prefer to infuse the water and strain out all plant material before adding the lye, as I have had problems with the lye interacting with the plant material, resulting in a faulty batch of lye/water that will have to be tossed out. But some soapmakers successfully add the plant material to the lye/water, and then strain the plant material out with no ill effects. Just keep in mind that the earlier you expose the colorant to lye, the more opportunity the lye will have to change the colorant; it is not uncommon to have a different resulting coloring depending on the methods you use).

Clays and Minerals

Clays and minerals have been used to color soap for centuries. The modern soapmaker, however, is discouraged from harvesting her own clay or minerals from her back yard. Direct from the earth, these colorants contain bacteria which could cause mold, as well as unhealthful inorganic matters which can be absorbed by the skin such as lead, arsenic and tin oxide.

When choosing a clay or mineral to color your soap, you will need to decide between purchasing "industrial grade" or "cosmetic grade" pigments. The difference between these two is the level of processing the colorant has undergone. As monitored and defined by the Food and Drug Administration (FDA), cosmetic grade colorants are safe for things such as lipsticks and cosmetics, as well as contact with food. Industrial grade colorants are appropriate for such things as paint.

Soap falls into an interesting "netherland" with regard to industrial versus cosmetic colorants. According to the FDA, soap is not a cosmetic. Therefore, you are not required to use cosmetic grade colorants in your soap. And, according to one processing plant I spoke with, there are several industrial grade pigments which would have been adequately processed for contact with the skin. Since cosmetic grade colorants are several times more expensive than industrial grade, the decision on which to use is usually a personal one.

What are the advantages to these clays and minerals? Clays will give you earth-toned pinks and reds, pale greens and yellows and warm whites and browns. Clay is also famous for making the soap mildly abrasive (thus helping your soap to lather up better), and for being good for oily skin. Since clays are heavy, they are generally added to Cold Process at the trace and to Rebatched and Melt and Pour soap at the last minute, so as to be well suspended throughout the soap.

Minerals come in many colors, including ultramarine blue, ultramarine green, red ochre, yellow ochre, brown ochre, to name a few. While minerals do not produce brilliant reds, purples or yellows, their greens and blues are fabulous. Clays and minerals are very good choices when you are planning on creating a soap with a marbled or two toned effect. This is because these colorants are, by nature, heavy and non-water soluble. Therefore, when a stripe of blue is swirled next to a strip of green, the two colors will tend to keep a clear, visual line of separation. Other, water-soluble options will tend to "bleed" into each other.

Resins

Rosin, benzoin, peru balsam are examples of resins which have a time-honored tradition for use in soap. They arrive as thick, sticky substances with a consistency somewhere in between honey and tar. Resins are difficult to work with in because they do not dissolve in oil or water. It is best to dissolve them in as little alcohol as possible (alcohol can cause your CP soap to seize) and then add them to your soap base. In her book, Transparent Soapmaking, Catherine Failor suggests you dissolve resin in stearic acid first.

Generally, resins add rich brown hues, and often a warm vanilla like scent. Resins are known for having antiseptic, antioxidant and preservative qualities.

FD&C colorants

These are basically food colors. The nice thing about such colorants, is that they offer "jewel tones", as opposed to earth tones. They are problematic, however, because they are generally not stable in soap (see the following information for further discussion on stability.

Stability

Stability refers to the amount of change that a colorant will undergo in your bar of soap over time. An unstable color, for example, may change from a rich green to a muddy brown, or even fade out completely. An unstable colorant may also come off on your washcloth or stain your skin when the soap is used. Finally, unstable colorants tend to bleed, so that if you are seeking a two-toned effect, the colorant will eventually stain the uncolored portion of the soap with a mottled, uneven look.

There are three chemical processes which will affect stability over time. 1) The colorant's interaction with the lye and/or alkalinity of the soap base; 2) Color-fastness; 3) Oxidization.

When making Cold Process soap, some colors immediately change when they come into contact with lye. For example, the brilliant and exquisite red of beet juice is completely beaten down into a muddy tan when interacted with lye. Alkanet root produces a blue-lavender or a slate grey, depending not on how much you add, but on how superfatted or how alkaline the final bar is. FD&C colorants also have minds of their own when interacting with lye, and the resulting color is often not the same as when you first blend it in.

A careful soapmaker will test a colorant for its stability in the face of lye before committing an entire batch. To do so, she will first dissolve a teaspoon of lye into a couple of tablespoons of water. Then she will add the colorant and stir. Does the color change? If it does not, it will likely be stable in relation to the soap mix.

Colors which can be unstable in Cold Process often work wonderfully in Rebatched and Melt and Pour soap. Since bases vary, it is always wise to test a new colorant in your base before proceeding to make large quantities of finished product with it.

Color-fastness refers to the colorant's stability to light, and its tendency to stay fast in the soap. No matter the color of the soap bar, its lather should be white. Some colorants -- particularly FD&C colorants -- will not meet this criteria. Not only will they raise a colored lather, they will also tend to stain the washcloth and to fade over time when exposed to sun. Generally, a colorant which is not stable in the face of lye will also not be colorfast when exposed to light.

Oxidization is a process of change that a colorant can go through as it ages. Oxidization can be a problem with natural colorants such as fresh herbs and chlorophyll (which can go from a lovely green to a muddy brown). Certain things can be added to your soap to act as antioxidants, grapefruit seed extract being one of them. However, I do not have any personal experience as to whether an antioxidant additive will reduce the oxidization of a colorant.

Mineral and clay colorants, as well as commercially produced soap colorants are generally very stable in soap, neither fading nor bleeding over time. However, the colors will look different depending on the alkalinity of the base. As an example, our shimmery Blessing Blue looks like a very light Baby Blue in Melt and Pour soap, while in Cold Process soap, it becomes more slate grey.