Skim through

What it does: viscosity controlling, emulsion stabilizing 

The science

Hydroxyethyl cellulose is a polysaccharide derivative with gel thickening, emulsifying, bubble-forming, water-retaining and stabilizing properties. It is used as a key ingredient in many hair products due to its non-ionic and water-soluble nature. 

It's derived from cellulose, the major component of the cell wall of green plants. It is compatible with most co-ingredients and gives a very good slip to the formulas. 

Benefits for your hair

Promotes thickness of product

As a thickening agent, hydroxyethyl cellulose not only helps to improve the feel of a product but also ensures that the product spreads evenly and smoothly across the hair.

Promotes smoothness

This ingredient helps to make hair smooth and soft without being flaky.

TLDR 

Hydroxyethyl cellulose helps to thicken products and increase the smoothness of hair. It lends good slip to a formula and has good stabilizing properties.