Microcrystalline Wax — Frequently Asked Questions

Molecular shape. Paraffin is built from straight-chain alkanes that stack into large, regular plate crystals, giving a hard, glossy, brittle solid. Microcrystalline wax is built from branched isoparaffins and cyclic naphthenes of higher molecular weight, and those irregular shapes cannot pack into an ordered lattice. The very small crystals that result make the material flexible, tough and slightly tacky.

Laminating grades are softer, tackier and lower melting, and are used where adhesion and flexibility are the objective, as in laminating, coatings and adhesives. Hardening grades are higher melting and firmer, and are used to raise the melting point and toughness of a blend. The distinction is one of degree along a continuous range rather than two separate materials.

It stops larger candles cracking, improves adhesion to glass and mould walls so wet spots are reduced, retains fragrance and colour that would otherwise migrate to the surface, and raises the melting point. Its ability to bind far more oil than paraffin can hold is the key property, since it is oil and fragrance migration that causes most surface defects.

Typically a few percent up to around ten, depending on the effect wanted. Small additions improve adhesion and reduce cracking without much changing the melting point; larger additions make the blend noticeably softer, tackier and more flexible. Because it is considerably darker than refined paraffin in some grades, colour contribution should be checked on a trial batch.