Butylated Hydroxytoluene (BHT) is a synthetic, oil-soluble antioxidant used in tiny amounts to stop the oils and fats in a formula from oxidising, going rancid and losing colour or smell. In plain terms, it does not kill bacteria the way a preservative does, but it protects the oily part of your product so it stays fresh for longer. It is widely added to creams, lotions, sunscreens, makeup, shampoos and lip products, usually at well under one percent.
What BHT is and how it works
BHT (INCI name Butylated Hydroxytoluene, also called dibutylhydroxytoluene) is an organic compound with the formula C15H24O and CAS number 128-37-0. It is produced from p-cresol and isobutylene using sulfuric acid as a catalyst. The Azlok grade is an industrial-grade, white to pale-yellow, practically odourless material.
When oils are exposed to air, light and heat, they begin to oxidise. This is what causes that stale, "off" crayon-like smell in old carrier oils and creams. BHT interrupts this chain reaction by neutralising the free radicals that drive oxidation. It is an antioxidant, not a broad-spectrum preservative — for water-containing products you still need a proper preservative system to guard against microbes.
Common uses
- Carrier and fragrance oils: a pinch extends the shelf life of oils prone to going rancid.
- Creams and lotions: protects the oil phase from oxidation and rancid odour.
- Sunscreens and makeup: helps keep colour and texture stable over time.
- Shampoos, balms and lip products: stabilises the oily ingredients.
- Soap and candle making: useful where natural oils or fragrance oils tend to discolour or oxidise.
How to use BHT
BHT is oil-soluble, so it must be added to the oil phase of your formula, not the water phase.
- Weigh your total batch and calculate BHT as a percentage of the whole. Typical usage is very small — commonly around 0.01% to 0.1%, and rarely above 0.5%.
- Dissolve the measured BHT into your warmed oils or fats before combining with the rest of the formula.
- Stir until fully dissolved and clear, then continue with your normal method.
Because it is used in such small quantities, a 100 gram pack goes a very long way for a home maker. Always follow the recommended dosage for your specific formula type rather than guessing.
Safety and handling
This is an industrial-grade cosmetic raw material meant for formulation, not for eating.
- Do not ingest. Keep well away from children and pets.
- Work in a ventilated space and avoid breathing in the powder; wear gloves and eye protection.
- Use only within accepted cosmetic dosage limits — more is not better and can be counterproductive.
- Some people are sensitive to synthetic antioxidants, so patch-test finished products on skin before regular use.
- Refer to the product's COA and MSDS for detailed handling and specification data.
Buying and storage
Azlok offers BHT in 100 Gm, 500 Gm, 1 Kg, 5 Kg, 10 Kg and 20 Kg packs, so hobbyists and small businesses can both find a suitable size. It is made in India and starts at Rs. 199. Store it in a tightly closed container, away from heat, direct sunlight and moisture. Kept cool and dry, it has a shelf life of around 24 months. Buy a size that matches how quickly you formulate — for most home makers, the smaller packs are more than enough since the usage rate is so low.
FAQ
Is BHT a preservative?
Not in the antimicrobial sense. BHT is an antioxidant that prevents oils and fats from oxidising and going rancid. Water-based products still need a separate preservative to protect against bacteria, mould and yeast.
How much BHT should I add to a formula?
Very little. Usage is typically in the range of 0.01% to 0.1% of the total batch, and generally not more than 0.5%. Always follow the guidance for your specific product type.
Can I add BHT to carrier oils to make them last longer?
Yes. Because it is oil-soluble, a small amount blended into carrier or fragrance oils helps slow oxidation and delay that stale, rancid smell.
Does BHT dissolve in water?
No, BHT is oil-soluble. Add it to the oil phase of your formulation, not the water phase.
Is Azlok BHT safe for skincare products?
It is a cosmetic raw ingredient intended for use in properly formulated products at recommended levels. Do not ingest it, keep it away from children, and always patch-test your finished product before regular use.