As I mentioned yesterday, I was really surprised by the talc, so I had to write a post about it!
Talc is hydrous magnesium silicate with a chemical formula of Mg3Si4O10(OH)2 or H2Mg3(SiO3)4. It is the softest known mineral. It is used a lot in mineral make-up and most comparisons of fillers include "better than talc" or "not as good as talc" because it's been a staple for years.
Want a very technical link on talc? Here it is!
What are the benefits of talc in mineral make-up? It is hydrophobic. It absorbs moisture, acts as a lubricant, offers a slippery feel and increases spreadability, offers low covering power as it is translucent, and may offer some lustre without "undue glitter". You want to choose a talc with less than 200 mesh as this will feel smooth on your skin. Ironically, the smaller mesh sizes offer some grittiness, so micronized talc is probably not a great idea for mineral make-up.
What are the benefits for your skin? Talc can soothe inflamed or irritated skin, help with chapped skin or skin suffering from heat rash, and works as an oil absorber. It does this by creating a "shield" to protect your skin from the outside world (or as we know it, talc is occlusive). You can use talc as the main filler or use it as a substitute for the oil absorbers, calcium carbonate, starches, or kaolin clay.
Talc can be used at up to 70% as a filler for mineral make-up. You can find it in various forms, including delaminated talc. (Which, as far as I can gather, means it has been taken out of the fine, alternating layers of minerals (called lamellae) and made into another form. Hey, I haven't taken inorganic chemistry yet!) Any product made mostly with talc is going to have low lustre, low covering power, and great slip and glide.
And it's inexpensive. At $5.00 for 4 ounces, it's the most inexpensive filler out there (except, perhaps for calcium carbonate, and you aren't going to use that as the primary filler in anything!) You can use it as the filler for any mineral make-up product, even anhydrous products as it plays well with oils.
And no, I'm not talking about talcum powder. Talc is only one of the ingredients in talcum powder, the others being starches and other absorbers or slippery things to make it feel nice. If you do buy some talc, try making a nice talcum powder for yourself for those really hot days! You'll be happy you did!
Join me tomorrow for some experiments with talc!