In ceramic tile back adhesive and waterproofing coating, cement is modified by a high dosage of polymers. When the coating is cured, the polymers gradually forms a continuous film on a micro level, which intertwines the hydration products of cement. Then a soft and solid coating is formed on a macro level. These kinds of products mostly consist of emulsion and solid powder, and foams can be easily formed when being mixed and stirred. Therefore，it is important to choose a liquid or powdery defoamer with excellent compatibility. Polycarboxylic superplasticizer with high water-reducing rate and suspension-stable cellulose ether can be added to improve the workability and maintain the necessary fluidity and viscosity.