(A) Benzoin easily decomposes under heating and causes yellowing of the coating film. Too much benzoin will cause discoloration of light-colored powder coatings.

(B) As the thickness of the coating film increases, especially when it exceeds 120 μ, even if a large amount of benzoin is added, usually pinholes (thick film pinholes) appear on the surface of the coating film. Such thick film pinholes need to be added with other types of defoamers and benzoin to eliminate them.

(C) Benzoin cannot completely eliminate pinholes in some low temperature curing powder coatings:
In order to reduce the curing temperature, a curing accelerator is usually added to the polyester / TGIC system or polyester / epoxy mixed powder coating system, which causes the melt viscosity of the system to increase rapidly during heating and curing, so that a large amount of gas is wrapped in the coating. The layer cannot be completely released, resulting in pinholes. Practice shows that benzoin cannot completely solve this problem, and it also needs to be combined with other defoamers to solve it.