HPMC, on the other hand, is Hydroxypropyl Methylcellulose. It is produced by alkali treatment of refined cotton and further etherified using epichlorohydrin and chloromethane as etherifying agents, resulting in a nonionic mixed ether of cellulose. The degree of substitution is typically between 1.2 and 2.0, and its properties vary based on the ratio of methoxy and hydroxypropoxy groups.

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No information on the dusting potential of the additive was made available. The analysis (by sieving) of one batch of the additive8 showed that 100% of the additive had particles smaller than 420 μm.

Topical preparations:

Cellulose is the most frequent polysaccharide in nature consisting of (some hundreds up to ten thousands) β-glycosidic linked glucose molecules. It is the main constituent of plant cell walls and vegetable fibre. It occurs mostly associated with hemicelluloses and lignin. It is therefore a common component of plant-based feed for all food producing and companion animals. However, these animals are not capable to digest cellulose enzymatically due to the lack of cellulases. The monomer element of cellulose, glucose, will not be released from cellulose. But gastrointestinal microbes can split cellulose, the main degradation products are short-chain fatty acids. In a simplified view, monogastric animals cannot digest cellulose, small amounts are microbially degraded in the large intestine. Minor amounts of cellulose may be absorbed as such by paracellular transport (passing through the intercellular space) or by transcytosis (transcellular transport of macromolecules captured in vesicles). On the other side, animals with large fermentation chambers in the intestine, such as ruminants, horses and rabbits, utilise large amounts of cellulose as energy source. In summary, cellulose is a natural part of feed and plays a physiological role in nutrition of animals (see Section 3.2.1).

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.