ZF -801A , a new kind of quick drying silica sol for precise casting, mainly made of silica sol and combined with several organic polymers and macromolecule material, is specially used in fine casting for precoat to fabricate shell. It is characterized by the following advantages:
1.The drying time is apparently shortened. Generally, after about 2 hours the next layer can be done. The drying speed has gone up 50% in original condition and the production capacity is improved.
2.The silica sol, in which the organic polymers and special additives are added, improves phragmoid toughness and the coating performance. The craze crack and flash of the coating size are reduced. As a result the quality of the cast is improved.
3.The shell-mold that is easily broken has a high wet strength and low retained strength.
4.The silica sol has a longer service time as the polymers are alkaliproof and not moldy.
Notice: In the course of churning up and using the coating prepared by the quick drying silica sol, proper amount of distilled water should be added into it every 2-3days to keep its viscosity. When it is not used, seal it to keep the moisture and avoid the gelation.

Technical index：
Appearance：milky liquid
Solid content(%)≥：30
SiO2 content%≥：25
Na2O content %：0.2～0.4
Viscosity（25℃）mPa.s：≤15
Density（25℃）g/cm3：1.18～1.22
PH Value（stock solution ）：9～10.5
Shelf period：(normal temperature)six months
Packing：30KG plastic barrel