Paint swelling refers to the substantial increase in the viscosity of the paint on storage. Finally, it becomes a thick paste, even a colloidal block. Swelling is extremely detrimental to paint construction and affects quality. Swelling can take several forms:
(1) Liverization
Paints with high acid value and salt-based pigments undergo saponification reaction during storage to form a hard gel, just like pig liver, hence the name liverification. Once liver changes occur, it is not easy to recover. But when the hepatic changes are mild, a small amount of corresponding diluent can be added to dilute it for use. However, this kind of paint can only be used as a primer, if it is used to cover the surface, it will lose its gloss.
(2) Gelling
If the paint is heated, stored for a long time or the paint is over-polymerized, its base material will form a gelatinous mass together with the pigment particles. When the base material of the lacquer is gelled, generally the same kind of thinner can be added, stirred vigorously, and the gelation will be transformed into a uniform liquid again. For example, when tung oil is gelled, 3% glycerin can be added and heated in a short period of time to restore the original state.
(3) fake thick
Mainly occurs in paints with high pigment content. Its outer surface seems to be dull, but it can be restored as long as it is stirred vigorously with a wooden stick. False thickness, also known as thixotropy, generally can not be regarded as paint morbidity.
