Antifoam
Foam is generated when air enters a liquid containing a surfactant under the action of an external force, and the surfactant is oriented at the air-liquid interface. The hydrophobic group is oriented toward the air of the bubble, and the hydrophilic group is oriented toward the water, producing a large number of bubbles. There are several reasons for generating bubbles in coatings.
1: Air will be entrained into the paint due to mechanical mixing during paint production;
2: Air brought in during coating process, such as brush coating, roller coating, high pressure airless spraying, etc.
3: Two-component coatings, when mixing before construction, the air mixed in by stirring.
4: The pore of the painted object is more, due to the infiltration of the paint air is driven out to form air bubbles, such as in the porous wood and cement wall paint construction.
5: Air bubbles produced by chemical reaction, such as the reaction of polyisocyanate in two-component PU paint with trace water will produce carbon dioxide.
Foam is unstable by nature, and its breaking goes through three processes namely redistribution of bubbles, thinning of film thickness and rupture of film. But a more stable foam system, to go through these three processes to achieve natural defoaming needs a long time, all the production of most of the use of defoamers. It is generally believed that the defoamer makes the foam liquid membrane local surface tension decrease and defoaming. Because of the low surface tension of the defoamer itself, it always penetrates into the foam system in the form of particles to make the surface tension of the foam film decrease locally. As the liquid with low surface tension always flows to the liquid with high surface tension, the film wall gradually becomes thin, and is strongly pulled by the surrounding film layer with high surface tension, resulting in stress imbalance and finally leading to bubble rupture.
At present, there are three major types of general antifoam agents: mineral oil antifoam agents, silicone antifoam agents, and silicone-free polymer antifoam agents.

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