As a first approximation we chose to focus on gloss, the aspect of appearance that is at once of commercial importance and is a factor that is largely dependent on surface morphology through a surface roughness variable. The dependence of surface roughness on pigment particle size distribution and degree of flocculation was investigated. Despite the obvious complexity of the weathering process we found similarities in the dependence of high gloss on the presence of many small well dispersed pigment particles as was seen in earlier studies of unweathered surfaces. The dependence of surface roughness on PVC however varied significantly with the degree of weathering. Below are figures from the simulation.
Figure shows coating with a high degree of flocculation.
Graphic of simulation shows weathered surface with air shown above in gray and a thin layer of paint below. Note surface roughness has decreased and thus surface will have glossier appearance. Spheres depict titanium dioxide pigment particles that are randomly placed according to the Matern cluster process a simple type of Neymann-Scott point process. We proposed the construction of computer graphic images of surfaces depicting these relationships that could be used to visualize the trade-offs of various formulation strategies. These images could play a potentially important role in producing coatings with the most desirable gloss characteristics, given the constraints of cost and ease of manufacture.