Cyclomethicone + other cyclo-siloxanes

What is it? Cyclomethicone is an ultra-light volatile silicone ingredient. “Cyclomethicone” is a generic/broad term for one or more cyclic siloxanes, primarily cyclotetrasiloxane (D4), cyclopentasiloxane (D5), and cyclohexasiloxane (D6). Learn more here.

There are other cyclic siloxanes (D3–D7) but D4, D5, and D6 are the primary ones for cosmetic use. Cyclotetrasiloxane (D4), cyclopentasiloxane (D5), and cyclohexasiloxane (D6) are sold as isolated ingredients, but I’ve only ever found cyclopentasiloxane (D5) available to homecrafters.

If you check product datasheets you might find out that the “cyclomethicone” you’re looking at is almost entirely cyclopentasiloxane (D5). Check the datasheets from your supplier to learn more about the specific products you’re looking at. For example, this datasheet for the cyclomethicone sold by Windy Point shows it is 99–100% cyclopentasiloxane (D5), with a small amount of cyclotetrasiloxane (D4).

From my research, I’d avoid cyclotetrasiloxane (D4) where possible as Health Canada has concerns about it accumulating in the environment.

INCI Varies; check with your supplier. It’s usually “Cyclomethicone” or a list of the component cyclic silicones comprising that particular product, like “Cyclotetrasiloxane (and) Cyclopentasiloxane”. If you are purchasing an isolated cyclic siloxanes the INCI should reflect that (eg. Cyclopentasiloxane).
Appearance Thin clear liquid
Usage rate I’ve seen widely varying maximum usage levels; everything from 10% to 95%. Check with your supplier for the specific product you have.
Texture Ultra-light, slippy, luxurious.
Scent Nothing noticeable
Absorbency Speed Very fast
Approximate Melting Point Liquid at room temperature
Solubility Oil, silicones
Why do we use it in formulations? Cyclomethicone adds wonderful slip to our products and helps reduce tackiness. Small concentrations add a really gorgeous, expensive-feeling skin feel. Higher concentrations of cyclomethicone help “lighten” products, speeding up dry down/absorption speeds.

It is commonly used as a diluent in hair oils to create products that don’t leave the hair looking greasy. A small amount of oil will be diluted in a larger amount of cyclomethicone; when that is applied to the hair the cyclomethicone will readily evaporate, leaving a tiny amount of well-distributed oil behind on the hair.

In cosmetics, you’ll find it in all kinds of cream cosmetics, where it provides body to the cosmetic and then evaporates readily after application, leaving behind the pigment without any added oil that would compromise wear time.

Do you need it? No, but if you love making cosmetics and/or have hair that is not very tolerant of oils, cyclomethicone is a wonderful ingredient to have on hand.
Refined or unrefined? Cyclomethicone only exists as a refined product.
Strengths Cyclomethicone is a very versatile ingredient that improves the skin feel of anything I’ve ever tried it in.
Weaknesses The biggest weakness of cyclomethicone (and other silicones) is all the negative myths about it. These myths include the idea that silicones suffocate the skin, cause acne, and are bad for sensitive skin. If you have concerns about silicones, please review these resources:

You certainly don’t have to use silicones in your products if you don’t want to, but don’t avoid it based on misinformation 🙂

Alternatives & Substitutions You can generally use cyclomethicone and cyclopentasiloxane interchangeably. I have both and can’t really tell a difference between the two. You can also try Dimethicone 1.5, which is lightweight and volatile (not to be confused with Dimethicone 350 or other non-volatile silicones).

There are several natural silicone alternatives on the market now, like “LuxGlide” and “LexFeel”. The ones most suitable for replacing cyclomethicone are “LuxGlide N5” and “LexFeel N5”.

You could also try ultralight emollients/esters like Isoamyl laurate, Coco-Caprylate, isoamyl cocoate, C12-15 alkyl benzoate, or Neossance® Hemisqualane, but even these lightweight emollients are significantly heavier than cyclomethicone and will create a heavier end product, especially if the cyclomethicone is used at high concentrations to create an ultra-light end product.

Isododecane is similar to cyclomethicone in terms of viscosity and volatility, but I find it is even more volatile. You could try blending it with an ultralight emollient as a cyclomethicone alternative (I’d probably start with about 90% isododecane/10% ultralight emollient).

How to Work with It Include it in the oil phase of your products; it should be cold-processed as it will readily evaporate (and possibly burst into flame) when heated (the flashpoint is 77°C [169°F]).
Storage & Shelf Life Stored somewhere cool, dark, and dry, cyclomethicone has an indefinite shelf life. Keep it away from sparks and heat sources as the flashpoint is 77°C (169°F)
Tips, Tricks, and Quirks “Silicones… aren’t biodegradable, but they are degradable – they degrade in the environment, and turn back into silica (sand), carbon dioxide and water.” –Lab Muffin
Recommended starter amount 100mL (3.3fl oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Cyclomethicone


Posted on

August 15, 2020