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 like 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 Recipes that Use Cyclomethicone

Dimethicone 350

What is it? Dimethicone 350 (also known as Dimethylpolysiloxane) is a mid-weight, non-volatile silicone.
INCI Dimethicone
Appearance Semi-viscous clear liquid
Usage rate Up to 80%, though I typically use it in the 1–5% range
Texture Rich, slippy, smooth. Typical of silicones.
Scent Nothing noticeable
Absorbency Speed Slow
Approximate Melting Point Liquid at room temperature
Solubility Oil, silicones
Why do we use it in formulations? Dimethicone 350 adds wonderful slip to our products and helps reduce tackiness. Small concentrations add a really gorgeous, expensive-feeling skin feel. It helps improve spreading, offers skin protection, and conditions the skin and hair. It can also reduce soaping in lotion formulations. It is also an FDA approved skin protectant.
Do you need it? No, but I do love how small concentrations of Dimethicone 350 allow me to work with higher concentrations of good-for-skin ingredients that can make products feel tacky. It’s also a wonderful, super-easy way to improve slip & skin feel.
Refined or unrefined? Dimethicone 350 only exists as a refined product.
Strengths Dimethicone 350 is a very versatile ingredient that improves the skin feel of anything I’ve ever tried it in. It is non-irritating (suitable for those with sensitive skin) and will not aggravate conditions like Pityrosporum Folliculitis (a.k.a. fungal acne).
Weaknesses The biggest weakness of Dimethicone 350 is all the negative myths about it. These myths include the idea that silicones suffocate the skin, cause acne, are toxic, and are bad for sensitive skin. Dimethicone and other silicones have been studied and reviewed extensively by experts around the world and have been continuously found to be not only very safe, but beneficial to the 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 In products where you are using Dimethicone 350 at 5% or less, you could try a higher viscosity version, like Dimethicone 500 or Dimethicone 1000. With that low of a usage rate, the dimethicone will be diluted so much that the thicker version is unlikely to impact the end product much (if a very low viscosity is important to the final product [i.e. if it’s supposed to mist] then swapping in a higher viscosity of dimethicone probably isn’t the best idea).

There are several natural silicone alternatives on the market now, like “LuxGlide” and “LexFeel”. The ones most suitable for replacing Dimethicone 350 are “LuxGlide 350” and “LexFeel 350”. I find the natural alternatives do not offer the same level of slip and richness as Dimethicone 350, so you may want to increase the concentration to compensate.

You could also try rich, slippy oils as an alternative (something like oat oil), though these will not offer the same level of de-tack-ifying and skin smoothing. The importance of this is very formula dependent, and I also find perceptions of stickiness/tackiness are very personal. If you’re not very sensitive to stickiness (or just plain ol’ don’t mind it) you are less likely to notice the loss of silicone in a formulation.

Dimethicone 1.5 is not a good alternative for Dimethicone 350; the 1.5 version is ultra-thin and lightweight, and evaporates quickly. It is much closer to Cyclomethicone and Cyclopentasiloxane than Dimethicone 350.

How to Work with It Include it in the oil phase of your products; it can be hot or cold processed. Check with your supplier for the specific product you have as recommendations can vary.
Storage & Shelf Life Stored somewhere cool, dark, and dry, Dimethicone 350 has an indefinite shelf life.
Tips, Tricks, and Quirks The “350” in Dimethicone 350 indicates viscosity. The higher the number, the more viscous the dimethicone. Dimethicone 500 and 1000 are also fairly readily available to home crafters.
Recommended starter amount 100mL (3.3fl oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Recipes that Use Dimethicone 350

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