Dimethicone (polydimethylsiloxane)

Dimethicone is the cosmetic (INCI) name for polydimethylsiloxane, a silicone polymer. It's a clear, colourless, odourless liquid that feels silky rather than oily and spreads easily into a thin film.

• Formula: (C2H6OSi)n, repeating -Si(CH3)2-O- units
• CAS number: 9006-65-9 (also listed as 63148-62-9)
• Solubility: doesn't mix with water; mixes with many oils
• Viscosity: the number in the name, here 350, is usually the viscosity in centistokes (cSt). 350 cSt pours a bit like light honey.

Chemically it's very stable and doesn't react with most cosmetic ingredients, which is why it's so widely used.

Azlok lists Dimethicone (DMPS 350) in its cosmetic raw ingredients range. 350 cSt is a middle grade: thicker grades give more cushion and shine, thinner ones feel lighter and spread faster. The product name doesn't state a pack size, so check the listing.

For the current rate, see today's price per kg.

• Hair care: serums, conditioners and leave-ins for slip, shine and easier combing.
• Skin care: creams and lotions, where it reduces greasiness and leaves a smooth, soft finish.
• Makeup: primers and foundations for a smooth glide.
• Industry: an antifoam in processing, a lubricant, a mould release agent and a heat-transfer or damping fluid.

In cosmetics it's mainly there for feel. It forms a light, breathable film on hair and skin that reduces friction, which is why combing gets easier and creams stop feeling sticky. A little goes a long way.

Typical published use levels are low, roughly 1–5% in creams and lotions. Hair serums often use much more silicone, usually blended with lighter silicones or oils. These are typical ranges, not rules.

1. Emulsions: add dimethicone to the oil phase, or stir it in during cool-down below about 40 °C. It doesn't dissolve in water, so it needs an emulsifier to stay mixed in a lotion.
2. Anhydrous serums: blend with carrier oils or lighter silicones and stir well. No heating is needed.
3. Start small: try 2% in a lotion test batch and adjust for feel. Too much can feel slippery or leave a film.
4. Patch test finished leave-on products before regular use.

• Low hazard to handle, but avoid getting it in the eyes. If it does, rinse with water.
• Spills are very slippery. Soak up with paper or sawdust, then clean the surface with detergent.
• It's hard to wash off equipment with plain water. Use hot water with a strong detergent.
• Store in a closed container at room temperature, away from strong oxidisers.
• Keep it away from children.
• Don't pour it down drains. Soak up waste and dispose of it as solid waste as local rules allow.

• Lotions and creams: 350 cSt is a common all-round choice.
• Very light hair serums: some makers blend 350 with a thinner silicone or oil to reduce the heavy feel.
• Production: for 25 kg or more, send a bulk inquiry.

If you sell finished cosmetics in India, keep supplier documents ready, as products must meet BIS and CDSCO rules.