Answer:1) whiteness: although whiteness can not determine whether HPMC is good, and if it is added in the production process of whitener, will affect its quality. However, good products are mostly white.
2) Fineness: HPMC fineness generally has 80 mesh and 100 mesh, 120 purpose is less, the finer the fineness is generally better.
3) transmittance: the hydroxypropyl methyl cellulose (HPMC) into the water, the formation of transparent colloid, see its transmittance, the greater the transmittance, the better, that less insoluble matter inside.
4) Proportion: the larger the proportion is better. It's usually because it's high in hydroxypropyl,
High hydroxypropyl content, water retention is better.