12-hydroxystearic acid (12-HSA) is used mainly to make lithium and calcium soaps that thicken lubricating grease. Smaller volumes go into cosmetics, coatings, plastics, oil-gelling agents and specialty esters.
12-HSA is made by splitting hydrogenated castor oil into its fatty acids and glycerine. The product is a saturated C18 fatty acid with a hydroxyl group on the twelfth carbon. It is sold as flakes or powder.
Why grease makers use it
When 12-HSA reacts with lithium hydroxide, it forms lithium 12-hydroxystearate. This soap builds a fibre network that holds oil in place. Greases made this way have a high dropping point, good water resistance and good mechanical stability.
That is why lithium 12-hydroxystearate greases are among the most widely used multipurpose greases. Complex greases and calcium greases also use 12-HSA. For a grease maker, the acid value and hydroxyl value decide how much alkali is needed and how the soap performs. Our guide on the acid value of 12-HSA goes into detail.
Other uses
- Metal soaps such as zinc, calcium and magnesium 12-hydroxystearate, used as lubricants and stabilisers in plastics.
- Cosmetics, where it adds structure to sticks, creams and oil gels.
- Gelling agents that turn oils into solid or semi-solid forms.
- Esters and estolides used in lubricants, inks and coatings.
- Rheology additives for paints and sealants.
What to check before you buy
Commercial 12-HSA is not pure. It also contains stearic acid, palmitic acid and some unsplit material, and the share of each varies by plant. That affects grease yield and performance.
Ask for a full certificate of analysis with acid value, hydroxyl value, iodine value, melting point, colour and moisture. Compare it with your own lab results on a sample. Our guide on writing a specification for HCO or 12-HSA covers the limits to set.
How 12-HSA differs from HCO
Buyers sometimes treat HCO and 12-HSA as the same thing. They are not. HCO is a triglyceride, so it still carries glycerine in the molecule. 12-HSA is the free fatty acid, with the glycerine removed during splitting.
That difference matters in use. A grease maker can make soap from either, but 12-HSA reacts faster and releases no glycerine or water from glycerine into the kettle. Many grease plants therefore prefer 12-HSA, while some use HCO to save a processing step.
Because 12-HSA is made from HCO, its quality depends on the HCO feedstock. A plant that makes both on one site controls the whole chain. A plant that buys HCO in depends on someone else's hydrogenation. Ask which applies before you approve a supplier, and read what HCO is used for for the feedstock side.
Next step
We find 12-HSA plants, check their documents, have lots tested and supervise loading. If 12-HSA is on your list, book a free sourcing review.