Some mica colorants can and do have TD in them and some have oxides, ultramarines, etc. in them. It's how the colors & shades are mixed. Oh, I see that has already been addressed..... Additionally, one can purchase pre-mixed colorants from a few reputable soap suppliers, so they also come pre-mixed for the buyer who does not want to mix their own. I have been tempted at times, but prefer to do it myself and save the money. For example, LabColors come as a liquid colorant (
example); lakes can be purchased pre-mixed (
example); mica mixes can be purchased pre-mixed (
example.) TD can be purchased pre-mixed in Castor oil (
example) as can some other colorants (although listed as Lip Colors at TBK, they are also listed as CP stable). These are just some examples of pre-mixed colorants sold by a few reputable soap suppliers.
Hopefully I got this posted in the right spot. I know there has been lots of talk about mixing micas in water or oil with a marble in the bottom of the bottle. I see that TD is in a lot of the micas so I gave it a shot. Some seemed to mix OK I guess, although the mica did settle to the bottom of the bottle after it set for a while. For those that didn't mix well I used 1 part glycerin and 3 parts water. It did seem to blend better. I'm not sure if I should put a preservative in the bottles of the ones that have glycerin (I'm sure I will not be using them up for quite a while). Anyone have thoughts on the glycerin/water mixture and if I should add a preservative?
GSC, I have pre-mixed micas and colorants in little bottles on occasion, using a stainless steel ball inside the bottle for shaking it up. When pre-mixing, it's good to check if your micas are listed by the supplier as water or oil dispersable. If it says one only, that's what you should use. Sometimes it's both. The beauty of glycerin is that it can be used for either water or oil dispersable colorants.
And yes, that ball (for me it's actually a stainless steel fishing weight because that was more available in my area at the time I was shopping) is essential to keep the mixture well mixed after it has sat for awhile.
Whether to use a preservative, I would err on the side of caution if I didn't think I'd use them soon, and take into account the mixing method. Did you sterilize or disinfect your bottle prior to filling it? If so, I don't think the need to preserve is really that great. BUT if you make enough to last you for several months and you mixed with water, then maybe so. It really depends on your personal circumstances, IMO.
I have used vegetable glycerin for mixing colorants and found that if I use
very little, it does not negatively impact my soap. However, the first time I did this, I over-used the glycerine and ended up with extremely colorful spongy soft soap. It was a pointillism pour, so lots of colors were required, and when you add lots of color with way too much glycerin, well ... spongy soap. So after that I became very stingy with the glycerin when mixing with colorants.
There are pros & cons to pre-mixing for multiple use, and you have to decide if it works for you. I liked it, but had to find another place to keep the filled pre-mix bottles, when I already have so much to keep track of. But while they lasted, I kept a few pre-mixed colorants in a little drawer organizer bin right next to my soaping worktable. That was convenient for a quick color additive. They were also great for on-the-go soaping; I grabbed what I had when I took a trip (I soap when I travel) & the colors were already to go.
Drawbacks: limited amount of pre-mixed colors ready, so that limited my choices unless I wanted to make more. More bottles to clean after they were empty. Small size of the bottles makes drying time seem to take longer due to shape and size, even when disinfected with 70% alcohol (slower evaporation with 70% also leads to greater disinfecting because it remains on the surface longer than higher percentage alcohol). More storage area needed. More things to label (labeling is extremely important.)