Complete Guide to Eliminating Bubbles in Coatings: Causes and Solutions

Bubbles generated during coating production or application not only compromise surface smoothness but also reduce adhesion and densification. Key causes include:

Surface Tension Imbalance

Surfactants (e.g., wetting agents) in coatings reduce surface tension. However, air entrapment during stirring or spraying forms stable foam encapsulated by liquid films.

Process Conditions

During high-temperature baking, coating viscosity drops, allowing bubbles to rise. Rapid solvent evaporation then solidifies the surface, trapping bubbles as pinholes. High-pressure spraying or roller coating exacerbates air entrainment.

Material Limitations

In high-solids or high-viscosity coatings, bubbles migrate slowly, and high elasticity further prevents rupture.

Chemi Tech Defoaming Solutions

Addressing these challenges requires synergistic defoamer properties and process adjustments:

Precise Surface Tension Control

Chemi Tech defoamers utilize fluorosilicone modifiers to achieve surface tension (≤22 mN/m) lower than coatings, enabling rapid bubble rupture without cratering.

Thermal Stability & Compatibility

For bake-cure coatings, defoamers withstand ≥150°C without decomposition. Chemi Tech’s polyether-siloxane copolymers ensure continuous defoaming while maintaining compatibility with epoxy/polyurethane systems.

Application Adaptability

For spray processes, Chemi Tech foam-suppressing defoamers (0.1%~0.3% dosage) inhibit bubble regeneration. For brush/roller applications, fast-defoaming agents shorten bubble duration.

Case Study

An industrial coating client resolved bubble-induced bumps during high-pressure spraying by:

Adding Chemi Tech defoamers during resin grinding for uniform dispersion;

Reducing spray pressure from 0.6MPa to 0.4MPa to minimize air entrapment;

Achieving 95% reduction in pinholes and surface roughness (Ra) ≤0.3μm.

Conclusion

Effective bubble elimination combines material science and process optimization. Chemi Tech defoamers deliver precise surface tension control tailored to diverse application scenarios, ensuring superior coating quality.