Hydrogenated Castor Oil (Castor Wax) — Frequently Asked Questions

Because it retains free hydroxyl groups, which almost no other wax has. Those hydroxyls hydrogen-bond to one another and to polar surfaces, building a three-dimensional network through the liquid that a purely hydrocarbon wax cannot form. The result is that a small addition gels an oil, holds pigment in suspension and stops a liquid system separating on standing.

Around 85 to 88 degrees Celsius, the highest of the common vegetable-derived waxes. That makes it the most effective hardener available to a formulator working with soft vegetable waxes, since a small addition raises the melting point and firmness of a blend appreciably. The oil phase must be heated above that point to dissolve it fully.

Castor oil is a viscous liquid; hydrogenating it saturates the double bond in its ricinoleic acid chains while leaving the hydroxyl group at carbon 12 intact, converting the liquid into a hard, brittle white wax. The hydroxyl groups that give both materials their unusual behaviour survive the process, which is why the wax retains the polarity that makes it such an effective structurant.

Yes. Micronised castor wax has a much finer particle size and a far larger surface area, so it disperses and builds structure more efficiently at lower addition, and it is used where the wax is added to a cold system rather than melted in. Standard flake and powder grades are used where the formulation is heated above the melting point anyway.