Cyclomethicone

Cyclomethicone is the cosmetic name for cyclic silicones, ring-shaped molecules made of repeating units of silicon, oxygen and methyl groups. Unlike dimethicone, which stays on the skin or hair, cyclomethicone is volatile: it carries other ingredients, leaves a silky feel and then evaporates.

• Main types: D5 (decamethylcyclopentasiloxane) is the most common; blends may contain D4 or D6
• D5 formula and CAS: C10H30O5Si5, CAS 541-02-6
• D5 molar mass: 370.77 g/mol
• Appearance: clear, colourless, nearly odourless, water-thin liquid
• Solubility: does not mix with water; mixes with many oils, other silicones and alcohol

Because it evaporates, it leaves no greasy film. That is why a roll-on antiperspirant or a primer feels dry within a minute or two of applying it.

Azlok lists cyclomethicone in its cosmetic raw ingredients range, for makers of hair serums, primers, body oils and roll-on products. The pack size, and whether it is D5 or a blend, should be checked on the product page or label. See today's price per kg.

• Hair care: anti-frizz and shine serums, leave-in sprays, often with dimethicone
• Skin care and makeup: primers, light lotions, sunscreen bases and foundations, for a dry, non-greasy feel
• Antiperspirants and deodorants: as the carrier that evaporates after application
• Oil blends: thinning heavy oils so they spread and feel lighter

It is not a moisturiser by itself, since most of it leaves the skin. It is there for feel and spreading.

Use levels are typical ranges from cosmetic suppliers:

In emulsions, add it to the oil phase or after cooling below about 40 °C, since it evaporates when heated. Close containers quickly; open beakers lose product to the air. Patch test finished products on the inner arm for 24 hours.

Finished cosmetics sold in India need to meet BIS and CDSCO requirements, so if you sell what you make, keep batch records and check the rules that apply to your product.

• Cyclomethicone is a combustible liquid. Keep it away from flames and hot plates.
• Spills make floors very slippery; wipe up at once with absorbent cloth.
• Avoid getting it in the eyes; rinse with water if it happens.
• Store tightly closed in a cool place, away from sunlight, or it slowly evaporates.
• Keep away from children.
• Don't pour it down drains; cyclic silicones persist in the environment. Absorb small amounts and dispose with solid waste.

For serum trials and small batches, a small pack is enough. Hair serum makers use it as the main ingredient, so they go through it quickly and should consider larger packs. If you sell into export markets, check current rules on D4 and D5 in the destination country, as the EU has restricted them in some products. For 25 kg and above, use the bulk inquiry form.