Trimethylsiloxysilicate (and) Polypropylsilsesquioxane (Flake Resin)

Dow describes this product as “a unique combination of MQ and T propyl silicone resin. This combination of resin technologies has been especially developed to provide both excellent transfer and wash resistance combined with a flexible film and comfort of wear in skin and cosmetics applications. Even with stretching and washing the film formed by this product remained smooth and undamaged. In sunscreens it enhanced the SPF wash off resistance.” (source)

You can find Trimethylsiloxysilicate (and) Polypropylsilsesquioxane in tons of different long-wearing cosmetic products where it improves wear time and rub-off resistance. Examples include Fenty’s Sun Stalk’r Instant Warmth Bronzer, Sephora’s Lip Last Matte Lipstick, ITEM Beauty’s Air Hug Clean Lightweight Full-Coverage Concealer, Kaja’s Don’t Settle Concealer, Tarte’s Quick Dry Matte Lip Paint, and KVD’s Cake Pencil Eyeliner.

Trimethylsiloxysilicate is also manufactured and sold as a stand-alone ingredient (DOWSIL™ MQ-1600 Solid Resin). Trimethylsiloxysilicate (without Polypropylsilsesquioxane) is very commonly used in long-wearing cosmetics for its film-forming and long-wearing properties. Examples include Bobbi Brown’s Long-Wear Gel Eyeliner, Urban Decay’s Primer Potion, Laura Mercier’s Caviar Stick Eye Shadow, Anastasia Beverly Hills’ DIPBROW™ Pomade, and NARS’ Powermatte Lip Pigment.

Both Trimethylsiloxysilicate and Polypropylsilsesquioxane are also available as components of other blended products. For instance, DOWSIL™ 593 Fluid is Dimethicone (and) Trimethylsiloxysilicate and DOWSIL™ 670 Fluid is Cyclopentasiloxane (and) Polypropylsilsesquioxane, and Specsil K-75 is Isododecane (and) Trimethylsiloxysilicate.

Grant Industries Inc. manufactures several solutions of Trimethylsiloxysilicate and Polypropylsilsesquioxane in different solvents: isododecane (Granresin MQI-T50), cyclopentasiloxane (Granresin MQC-T50), and dimethicone (Granresin PHQ-Fluid).

• Ethanol
• Isopropyl myristate (IPM)
• C12-15 alkyl benzoate
• Medium chain triglycerides
• Isododecane
• Cyclomethicone + other cyclo-siloxanes

Different solvents perform differently; which one you choose will depend on your formulation needs. If you’re unsure, take a look at some commercially available formulations that are similar to what you are planning on making. In my research, I have found that isododecane and cyclomethicone + other cyclo-siloxanes are the most popular choices.

If you read through the reviews for Flake Resin on TKB Trading you’ll see most users prefer isododecane as their solvent of choice, and TKB Trading also recommends isododecane for the best performance. I have seen products for sale that use cyclomethicone as the solvent. I have yet to find any products for sale that use isopropyl myristate (IPM), C12-15 alkyl benzoate, or MCT as the solvent for Trimethylsiloxysilicate (and) Polypropylsilsesquioxane.

I make my own version of Grant Industries’ Granresin MQI-T50 by weighing equal parts isododecane and Trimethylsiloxysilicate (and) Polypropylsilsesquioxane into a bottle (50% isododecane, 50% flake resin) and work with that. A reviewer named “Astarie D.” on TKB shared that they use an 80/20 mix of Isododecane and flake resin. Remember that isododecane is volatile, so if that’s your solvent you need to be careful heating it.

Film-formers like Trimethylsiloxysilicate (and) Polypropylsilsesquioxane are broken down by oil—that’s why oil cleansers work so well to remove waterproof makeup! With that in mind, it’s not a good idea to put oil in formulations that rely on Trimethylsiloxysilicate (and) Polypropylsilsesquioxane performing well. The oil will diminish the effectiveness of the Trimethylsiloxysilicate (and) Polypropylsilsesquioxane.

For a great starter formulation, try TKB Trading’s free Liquid Lipstick project! It can also be adapted into eyeliners, cream eyeshadows, blushes, and more.

Luisa True Skincare also has a very helpful post on formulating and making liquid lipstick that you can find here. This formulation uses just trimethylsiloxysilicate but does mention polypropylsilsesquioxane as a potential ingredient to include.