प्रोपिलीन ग्लाइकॉल (Propylene glycol (1,2-propanediol))

Propylene glycol (PG), also called 1,2-propanediol, is a small diol with two hydroxyl groups. It's made from propylene oxide. On cosmetic labels it appears simply as propylene glycol.

• Formula: C3H8O2
• CAS number: 57-55-6
• Molar mass: about 76.1 g/mol
• Appearance: clear, colourless, nearly odourless liquid, a little thicker than water, with a faintly sweet taste
• Boiling point: about 188 °C; it stays liquid down to about −59 °C
• Density: about 1.04 g/mL
• Solubility: mixes completely with water, ethanol and acetone

It dissolves many oils, fragrances and colours that water alone can't, and it lowers the freezing point of water. Those two facts explain most of its uses. It's also only mildly volatile, so it doesn't evaporate off the skin quickly the way alcohol does.

Azlok lists propylene glycol as a cosmetic raw ingredient. That makes it the right choice for creams, lotions, hair care, fragrance and other personal care formulations. The listing name doesn't state a pack size, so check the product page for the volume or weight.

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• Cosmetics and personal care: a humectant and solvent in moisturisers, gels, deodorants, shampoos and serums. It also helps other ingredients spread and penetrate.
• Fragrance: a carrier or diluent for fragrance oils in reed diffusers, room sprays and some attars.
• Food and pharma (with the right grade): a flavour carrier and humectant, and a solvent in oral and topical medicines. Food use needs food grade material within FSSAI limits.
• Industry: lower-toxicity antifreeze and heat-transfer fluids, aircraft de-icing, unsaturated polyester resins, paints and inks.
• Effects and lab: fog and haze machine fluids, and as a general lab solvent.

• Creams and gels: formulators commonly use propylene glycol at about 1–5% of a leave-on formula as a humectant. Add it to the water phase.
• Dispersing powders: premix gums such as xanthan with a little PG before adding water. It stops the powder from forming lumps.
• Fragrance dilution: it blends with many fragrance oils, but not all of them. Test a small amount first. If it turns cloudy, use another carrier such as dipropylene glycol or perfumer's alcohol.
• Heat-transfer or antifreeze fluid: follow the equipment maker's dilution chart. The right ratio depends on the lowest temperature you expect.

Patch test any skin product on the inner arm and wait 24 hours. Some people with sensitive skin react to propylene glycol.

• Propylene glycol is low hazard in normal use but can irritate eyes and sensitive skin. Wear gloves when handling it neat in large amounts.
• Don't confuse it with ethylene glycol, the toxic car antifreeze. Keep both clearly labelled.
• It's combustible. Keep it away from open flames and hot surfaces, and away from strong oxidisers.
• Close the container tightly. PG absorbs water from humid air.
• Store it in a cool, dry place out of direct sunlight.
• The cosmetic listing isn't sold for food, drinks or medicine.
• Keep it away from children and pets.
• Small amounts diluted with plenty of water can go down the drain. Take larger amounts to a waste handler.

For skin care, hair care, fragrance and craft work, the cosmetic grade is the right match. If you're making cosmetics to sell, keep the supplier's specification and SDS on file, as finished products in India must meet CDSCO and BIS requirements. Don't use it in food or medicine unless you have food or pharma grade material with a certificate.

Start with a smaller pack if you're testing formulas. Formulators and units needing 25 kg or more can ask for a quote through bulk inquiry.