Gabrosa M 300
Gabrosa M 300, Methyl hydroxyethyl cellulose, Cellulose ether, Gabrosa® M 300 is a non-ionic, water soluble cellulose ether intended as a water retaining and consistency improving additive to cement based mortars.
https://www.nouryon.com/product/gabrosa-m-300-methyl-hydroxyethyl-cellulose/