Glycerine — Frequently Asked Questions

Because it is recovered, not manufactured for its own sake. Every triglyceride split by transesterification releases glycerine as a co-product, so world supply tracks biodiesel and soap output rather than glycerine demand. The expansion of biodiesel flooded the market with crude glycerine, and refining capacity rather than raw availability became the constraint on high-purity grades.

Matter organic non-glycerol, the organic impurities in crude and technical glycerine including soaps, methyl esters, free fatty acids and methanol residues. It is the single most informative impurity measure for crude glycerine because it determines how much refining is needed and whether the material is usable in a given process. It appears on every crude glycerine specification.

Because it carries three hydroxyl groups on a small molecule, making it trifunctional. In alkyd manufacture it reacts with polybasic acids and drying oils to form the branched polyester backbone, and the third hydroxyl is what permits branching and subsequent crosslinking, which is what allows the coating to form a film rather than remaining a viscous liquid.

Crude at roughly 80 percent, technical grade, and refined at 99.5 percent or better meeting USP and EP monographs. The grade determines both price and application: crude is a feedstock for refining or for energy, technical serves many industrial uses, and refined is required for pharmaceutical, food and cosmetic work.