Cloud point vs. High cloud point

Posted: March 27, 2007

Tony O’Lenick examines the difference between cloud point and high cloud point.

Both cloud point and high cloud point refer to the solubility phenomenon that results in haziness; however, the source of the haziness and the conditions under which it is observed are quite different--and both can effect cosmetic formulations.

Cloud point or titer point: Many materials, like esters, have a wide range of molecular weight species present (C₈-C₂₂). These different components often solidify at different temperatures. As a product is cooled, a cloudiness often will form as the least soluble material begins to crystallize. Cloud point is the temperature at which the cloudiness is first observed. The evaluation is conducted on the pure product.

As the temperature is lowered, the materials may become solid, the cloudiness may remain, or the insoluble material may drop to the bottom as a precipitate. Upon warming, the cloudiness will disappear. Awareness of this is important to the cosmetic formulator, since often in a given formula, the higher molecular weight material present in a raw material might well contribute to cosmetic properties like feel. If the lower clouding components of the raw material are removed by cold filtering, the benefit they confer will be lost.

To guard against this loss, the appearance specification for this type of material should specify different temperatures--one above the cloud point and one at the cloud point. Thus, it is not uncommon to have a specification for a material specify a clear liquid at 50^oC and a hazy liquid at 10^oC.