सैलिसिलिक एसिड (Salicylic acid)

Salicylic acid is a white, odourless crystalline powder, chemically 2-hydroxybenzoic acid. In skincare it is called a beta hydroxy acid, or BHA. Unlike glycolic acid, it dissolves in oils better than in water, so it can work into oily pores.

• Formula: C7H6O3
• CAS number: 69-72-7
• Molar mass: about 138.1 g/mol
• Melting point: about 159 °C
• Solubility: only about 2 g per litre of cold water, but readily soluble in ethanol

It acts as a keratolytic, meaning it softens and loosens the outer layer of dead skin cells so they shed more easily.

Azlok lists Salicylic Acid under cosmetic raw ingredients, for people formulating face washes, toners, scrubs and shampoos. The pack size is on the product page.

It is not sold as a medicine or as IP/USP material. See today's price per kg.

• Skincare: exfoliant in face washes, toners and gels aimed at oily, congested skin and rough texture.
• Hair care: in scalp shampoos to help loosen flakes.
• Body care: in body washes and foot creams for rough, thick skin.
• Industry and lab: raw material for aspirin (acetylsalicylic acid), methyl salicylate and dyes, and a standard teaching-lab chemical.

Typical levels. Leave-on and rinse-off cosmetics usually contain 0.5 to 2%. In the EU, cosmetics are capped at 2% for most products and 3% in rinse-off hair products, and it is not allowed in products for children under three, except shampoos. Indian BIS standards and CDSCO rules apply to products sold here, so check the current requirements.

1. Dissolve it properly. It won't dissolve in plain water at useful levels. Dissolve it first in warm propylene glycol, butylene glycol or ethanol, then add to the rest of the formula. Undissolved crystals feel gritty and can sting.
2. Example: for 100 g of a 1% toner, dissolve 1 g in about 10 g of warm propylene glycol before mixing it into the water phase.
3. Check pH. It works best in mildly acidic products, around pH 3 to 4. Raising the pH too far can make it fall out of solution.
4. Patch test on the inner arm for 24 to 48 hours.

People sensitive to aspirin should avoid salicylic acid products. Use sunscreen during the day when using exfoliating acids.

• The powder irritates eyes and the nose. Wear safety glasses, gloves and a dust mask when weighing.
• If it gets in your eyes, rinse with water for at least 15 minutes.
• Don't swallow it. It is harmful in large amounts.
• Keep it away from strong oxidisers, strong bases and iron, which can colour it.
• Store tightly closed, away from light and moisture. It slowly discolours in sunlight.
• Keep away from children.
• Dispose of small amounts dissolved in plenty of water; follow local rules for larger quantities.

For skincare, the cosmetic listing is right. For medicines, you need IP or USP material from a licensed supplier instead. A 1% formula uses only 10 g per kilo of product, so a small pack covers many batches for home and small-brand formulators.

Lab and industrial users needing 25 kg or more should send a bulk inquiry.