1,  There are many kinds of cellulose on the market at present, there are domestic and imported, the production of dry mixed powder materials are more commonly used MC, HPMC, CMC. From the viscosity,there are low viscosity, medium viscosity, high viscosity, different viscosity of cellulose has different uses. CMC, sodium carboxymethyl starch (CMS) with “carboxymethyl” character, the price is cheaper, used in the inner wall of low-grade putty powder, has a certain thickening and water retention effect, can increase the leveling, but can not be applied in waterproof putty. Because the cellulose will react with cement, ash calcium powder. Cellulose MC, carboxyc-methyl cellulose (HPMC) chemical stability, mildew proof, water retention effect is the best, and is not affected by the change of PH value, viscosity from 50 thousand 200 thousand can be used. But in the production it is not the higher the better with viscosity , viscosity and bond strength is inversely proportional, the higher the viscosity, the smaller the strength, is generally between 50 thousand viscosity, the production of putty powder is more suitable, mainly increase the leveling, workability, can reduce the amount of cement. Another effect is that cement mortar has a solidification period, during the solidification period need to be maintained, water supply to keep wet. Due to the water retention effect of cellulose, the moisture required for cement mortar solidification is guaranteed from the water retention of cellulose, so the effect of solidification can be achieved without maintainence . The quality of dry cellulose, mainly viscosity, can be test the rotary viscometer, can also be compared in a simple way, the same viscosity of cellulose each take 1 gram, add 100 grams of water, put in a disposable, at the same time into the room which dissolution rate is faster, good transparency, good thickening effect. The better the transparency, the less impurities.