Whitening, Whitish

During the coating process and just after the coating, the surface of the coating is milky white, resulting in a cloud-like phenomenon of whitening and loss of light, which mostly occurs when volatile coatings are applied. Mechanical properties decline.

Reason:

(1) The air humidity in the construction site is too high.

(2) The boiling point of the organic solvent used is low and volatilization is too fast.

(3) The temperature of the coated object is lower than room temperature.

(4) Solvents and diluents contain water, or compressed air brings water.

(5) The selection and ratio of solvent and diluent are inappropriate, and the real solvent volatilizes too fast during the drying process, causing the resin to precipitate in the coating and turn white.

The first three reasons cause the moisture in the air to condense on the coated surface and penetrate into the coating to cause whitening.

Prevention:

(1) The ambient temperature of the coating site is preferably (15-25) ℃, and the relative humidity is not higher than 70%.

(2) Choose an organic solvent with a higher boiling point and a lower volatilization rate, such as adding a moisture-proof agent.

(3) Before painting, heat the object to be coated to make it slightly higher than the ambient temperature.

(4) Prevent moisture from being brought in by solvents and compressed air.

(5) Prevent resin from precipitation during film formation.