I'm Skylar and I'm new to the forum. I'm recently started a biochem track, but I've been getting more interested in cosmetic chemistry so I'm trying to learn as many practical skills as possible before finishing school. My question is a bit long-winded so please bear with me!
I've been reverse engineering different powder products pretty easily, but I'm challenging myself with a liquid matte lipstick. This is the LOI in order and the percent by weight concentrations I've worked out as a possible starting formula:
Isododecane - 52%
Trimethylsiloxysilicate - 17%
Cyclopentasiloxane (siloxane D5) - 12.25%
Dimethicone - 2.75%
Synthetic Beeswax - 3%
Disteardimonium hectorite - 2-3%
Kaolin - 2%
Hydrogenated Polyisobutene - ?
Silica Dimethyl Silylate - 2%
* <1% line (0.2-0.4% I'd assume)
In my research I pulled formulas from Kobo and ran across a blog post by a consultant who was reverse engineering the same product, but I disagreed with her assessment so I wanted to get a second opinion.
She removed some of the fluff from the formula (hydrogenated Polyisobutene, replaced kaolin with synthetic fluorphlogopite, etc.) and seemed to overlook the order of dimethicone and cyclopentasiloxane. She put dimethicone at 15% and said the cyclopentasiloxane content was from Bentone Gel (propylene carbonate and disteardimonium hectorite suspended in cyclopentasiloxane) at a concentration of 5%.
I think it's wholly possible that Bentone Gel is included, but, given the order of ingredients, my assumption is that this is actually dimethicone (>200) in cyclopentasiloxane. The non-volatile dimethicone would act to modify the evaporation rate of the cyclopentasiloxane and help with the formation of a film, right? Since that's generally at a ratio of 85/15 that would explain its placement in the LOI, as well.
Also, if I want to finish this out and test my version, I don't have access to Bentone Gel or synthetic fluorphlogopite (but, honestly, I would use silicone treated titanium dioxide because this is a matte formula and that will suspend and add opacity better). Could cyclopentasiloxane with dimethicone/vinyl dimethicone crosspolymer serve as a suspension and viscosity agent in the same way disteardimonium hectorite would?
If that isn't viable, there's a hectorite gel formula that's a suspension of stearalkonium hectorite and propylene carbonate in caprylic/capric triglyceride. I think I could incorporate that to the wax in the final phase, BUT are triglycerides soluble in isododecane even though they're not really hydrocarbons? It seems really basic, but I'm unsure. If not, I'd assume you'd need a high shear mixer....
Anyway, those are my crazy long questions! I appreciate any input!