What are the types of paint defoamers?

From the leveling of latex paint to the durability of industrial coatings, foam not only affects the quality of the coating, but may also cause a decrease in storage stability. As the core additive to solve this problem, the selection and use of coating defoamers directly affect the effect of the product. This article will deeply analyze the classification, applicable scenarios and scientific dosage of coating defoamers to help you easily cope with the foam challenge.

Types of coating defoamers

• Organic silicone defoamers: This type of coating defoamer is based on hydrophobic siloxane as the core ingredient, and the defoaming performance is enhanced by adding particles such as white carbon black. It has low surface tension and can quickly penetrate into the surface of the bubble film to achieve rapid bubble breaking. It is suitable for water-based and oil-based systems, especially in occasions where rapid defoaming is required (such as automotive coatings and industrial anti-corrosion paints).
• 
  
• Polyether defoamers: This type of coating defoamer is mainly based on polyoxyethylene-polyoxypropylene block copolymers, which have both defoaming and anti-foaming capabilities. It has strong chemical stability, high temperature resistance, non-toxic and non-corrosive, and is particularly suitable for water-based coatings with high environmental requirements (such as architectural latex paint and children's toy paint). In addition, polyether defoamers have little effect on the gloss of the coating and can avoid recoating obstacles.
• 
  
• Mineral oil defoamer: This type of paint defoamer is composed of mineral oil, hydrophobic particles and emulsifiers, which physically destroys the stability of the foam film. Its advantages are high cost-effectiveness and long-term defoaming, especially suitable for processes such as scraping and spraying. However, it should be noted that mineral oil defoamers may affect the transparency of the coating and should be used with caution in varnish systems.
• 
  
• Non-silicone defoamer: This type of paint defoamer does not contain silicone resin, which can avoid shrinkage problems and performs well in solvent-based systems (such as automotive repair paint). In addition, this type of defoamer has no negative impact on the adhesion of the coating and is suitable for multi-layer coating processes.

Dosage of paint defoamer

• High viscosity latex paint: recommended dosage is 0.3%-1.0%. High viscosity system is prone to stable foam, so the dosage of defoamer needs to be increased. It is recommended to add it twice: add anti-foaming defoamer in the grinding stage and add defoaming defoamer in the paint stage to reduce the dosage and improve the effect.
• 
  
• Low viscosity water-based paint: recommended dosage is 0.01%-0.3%. Foam in low viscosity system is easy to eliminate, but excessive amount should be avoided to cause shrinkage.
• 
  
• Special process paint: such as elastic pattern paint/real stone paint, it is recommended to use organic silicon defoamer with strong alkali resistance, dosage is 0.5%-1.0%; for transparent varnish, non-silicon polymer defoamer is preferred, and the dosage does not exceed 0.3% to avoid decreased transparency; for high temperature curing paint, high temperature resistant polyether defoamer should be used, dosage is 0.2%-0.5%.

Usage of paint defoamer

We need to divide the total amount of paint defoamer into two parts, add 50% in the grinding stage and the remaining 50% in the painting stage. For example, adding silicone defoamer in the grinding stage can reduce the amount and improve the diffusion effect. Secondly, the paint defoamer needs to be added slowly under high-speed stirring to ensure uniform dispersion. If the defoamer is separated into layers, it needs to be fully stirred to an emulsion state before use.