There are many factors in the paint formulation that have an effect on foaming and foam stabilization.
1: Surface tension The surface tension of the coating has a big influence on the defoamer, the surface tension of the defoamer must be lower than the surface tension of the coating, otherwise it can't have the effect of defoaming and foam suppression. Coating surface tension is a changeable factor, so the choice of defoamer should be constant surface tension, and then the surface tension factor into account.
2: The influence of other additives, most of the surfactants used in coatings and defoamers tend to be functionally incompatible relationship. Especially emulsifiers, wetting and dispersing agents, leveling agents, thickeners, etc. will have an impact on the effect of defoamers. Therefore, when various additives are used together, we must pay attention to the relationship between different additives and choose the best balance point.
3: Baking temperature Paint at room temperature into the high temperature baking, the beginning of the instant viscosity will drop, bubbles can be moved to the surface, however, due to the solvent evaporation, curing paint, surface viscosity increases, will make the bubble film more stable, stay on the surface will produce shrinkage holes and pinholes, so the baking temperature, the curing speed, the rate of solvent evaporation on the effect of defoamer also has an impact.
4: the solid content of the coating, viscosity, elasticity high solids thick film, high viscosity, high elasticity coatings are very difficult to defoam, in these coatings defoamer diffusion difficulties, micro-bubble bubble into a large bubble slow speed, foam to the surface of the ability to migrate to the surface of the decrease in the foam film viscoelasticity of the large unfavorable defoamer many factors. These coatings in the foam is quite difficult to eliminate, it is best to use defoamer and defoamer with the use.
5: Painting method and construction temperature There are many painting methods, such as brushing, roller coating, drenching, scraping, high-pressure airless spraying, screen printing and so on. The degree of foaming of the paint varies with different coating methods. Brushing, roller coating foam more than spraying and scraping, the most foam is the ink screen printing, and is not good to eliminate. Foaming is more frequent at higher temperatures than at lower temperatures, but it is better to eliminate foaming at higher temperatures than at lower temperatures.

Room termperature curing polysilazane, pls check IOTA 9150, IOTA 9150A. 
High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.