I have an ounce of silica here lying in my vanity kit, and after ignoring it for a few months, I finally found use for it again!
I’ve been using it as my oil control primer, and finishing powder, and I think it controls oilies really well. It makes my pores look smaller and reflects really good that makes my skin look really smooth. I’m not a chemistry major, but I have found this information about silica,
1.Silica contained in foundation adsorbs sweat and oils in skin, which prevents light reflection by sweat/oil and keeps makeup on the skin longer.
2.Spherical particle type of silica improves the smoothness and spreading of foundation and cream.
3.The smooth surface appearance of nail polish is created by silica particles in the polish.
4.Porous silica is used as an ingredient in powder perfume, which can keep the fragrance on the skin for a longer time.
5.Silica is contained in antiperspirant, which gives the smooth feeling after it is applied on the skin. – ref :chemistryquestion.com
Silica can be used alone as an oil control primer and finishing powder. For those not comfortable with the color, they can always mix it to their foundation for added oil control. Larenim is one of the brands that uses silica as one of their ingredients in mineral makeup (amorphous silica ), and their Mineral Silk is just the best in terms of oil control and reflecting light.
To sum up, silica is a great ingredient that jives well with oily and problem skin. A word of caution , though, please handle raw silica with care, and moderation, too, because too much of anything is hazardous.