Powder coatings curing process in the Oven
First,the solid particles are melted,then they combine together ,and finally they form a uniform film or coating over the surface .
Maintaining low viscosity of the coating for an adequate time is very significant to have a smooth and even surface. Having decreased during the curing process, viscosity tends to increase as soon as the reaction (gelling )begins. Thus ,reactivity and heat temperature have a significant role in creating a level surface.
Therefore,the more reactivity of the coating ,the faster occurrence of gelling and increase of viscosity , consequently,the outer surface of the coating would be more undulant (orange peeled). Furthermore ,faster curing leads to faster decrease of melted viscosity.
Particle size distribution of the coating is also effective in state and levelness of the surface . So that ,compared to larger particles,smaller particles combine with others in a shorter time. Elimination of larger particles may lead to having a finer and glossier surface with the a thinner film.