Glycol Distearate — Frequently Asked Questions

The pearl is crystalline, not a pigment. Heated into a surfactant base the glycol distearate dissolves; as the batch cools it comes out of solution as very thin plate-like crystals suspended through the product. Those plates reflect and refract light, and because the flow of the liquid aligns them, the result is the shifting luminous sheen associated with premium shampoos and washes.

Almost always the cooling rate. Large, well-formed, well-aligned plate crystals give a bright pearl, and they need slow cooling under gentle agitation to grow. Cooling the batch quickly, or stirring it vigorously while it sets, produces many small disordered crystals that scatter light diffusely, giving flat white opacity instead of lustre. Where cooling cannot be controlled, a pre-dispersed pearlising concentrate removes the problem.

Glycol distearate carries two stearic acid chains esterified to the ethylene glycol, while glycol stearate carries one. The di-ester is less soluble in a surfactant system, so it crystallises more readily and produces a stronger, brighter pearl. The mono-ester is more soluble and contributes more opacity and emolliency than pearl. Many commercial pearlising agents are blends of both.

One to three percent covers most shampoo and body wash applications, with the lower end giving a subtle sheen and the upper end a pronounced pearl with noticeable opacity. Above about three percent there is little additional visual gain and viscosity and cold stability can suffer. Pre-dispersed concentrates are dosed according to their active content, which is typically well below the neat material.