Some forms of soap colorants do not fit in the natural category. This does not mean that they should be ignored. Often the reason they are synthetically produced is that they were harmful in their natural form.
Pigments, F, D & C dyes and Mica are three synthetic colorants that I use when making handmade soap.
Adding the right amount of color to soap can be a bit tricky. It's best to start with a little bit and work your way up.
Remember as well that the final result is not always what you expect. Sometimes other ingredients in your recipe will change the color of your soap.
For the truest colors, be sure to use neutral colored base oils to begin with.
Fragrance oils can cause some very surprising color morphing as well.
We once had a soap batch seriously react with a fragrance oil. The soap batter started out blue, then while stirring in the fragrance, it turned green, brown and then pumpkin.
After the insulation period, the soaps color was dark purple! It was quite exciting to say the least. Luckily, this is rare and the most that usually happens is the color hue is not quite what you intended.
All that glitters is probably mica. At least when it comes to soap and cosmetics.
Mica is a mineral that is mined from the earth and then finely ground. It is later combined with pigments or dyes to give it color.
Micas sparkly appearance is most pronounced when used as a soap colorant in transparent soap where light can reflect off of the mica plates.
When used in cold process soap, the effect is much more subtle. Though mica only adds a light sparkle, the color it gives soap is fantastic.
Since mica does not dissolve in liquid but remains suspended, it does not migrate through the soap. This means that your designs will have crisp, clean lines that are well defined. Blue will not bleed into yellow and result in green like dyes tend to do.
When purchasing mica, be sure to purchase the right one for your application. Not all micas are suitable for cold process soap making and not all can be used in lip products.
Those colored with oxides and ultramarines tend to work better for cold process, hot process and room temperature soap making.
Those colored with dyes are often better for melt and pour soap making. Your supplier should be able to tell you which ones to purchase for your application.
There are two types of pigments used in soap making today. Ultramarines and oxides. Both work extremely well when used in cold process, hot process and room temperature methods of making soap.
In the past, pigments were mined from the earth but due to harmful impurities, they are now produced in a laboratory following strict guidelines. Be sure to purchase only cosmetic grade pigments from a soap ingredient supplier.
Like mica, pigments are not water soluble. Pigments remain suspended in the soap base and do not migrate. Any designs you make using them will have well defined lines.
F,D and C dyes are found everywhere. In the food you eat, your makeup and your medication. Hence the name F, D and C = Food, Drug and Cosmetic.
This form of colorant knows no boundaries! No matter where you put it in your soap, it will migrate elsewhere. It is best used for single shade soaps or where a blending of color is the goal.
Try using a dye as a base and white mica as a swirl. This results in a tone on tone swirl that is quite elegant.
Another technique is to layer two dyed portions of soap, blue and pink for example. As the soap cures, the point where the blue and pink meet will turn purple.