Which characteristic distinguishes coalescence curing?

Coalescence curing is characterized by the ability of certain coatings to form a continuous film through the merger of dispersed polymer particles without the necessity for additional catalysts. This process primarily involves the softening of the polymer particles as the coating is applied, leading to the particles fusing together upon evaporation of the solvent. The key aspect here is that the curing can occur at ambient temperatures under regular conditions, which means no external catalysts are needed to initiate or enhance the curing process.

In contrast, the other characteristics listed do not accurately describe coalescence curing. While some curing processes may require heat or rely on the evaporation of solvents, these aspects are not exclusive to coalescence. Moreover, longer cure times are not a defining feature of coalescence curing, as this type of curing may actually result in faster film formation under the right conditions. Thus, the main distinguishing feature is indeed the ability to cure without the use of additional catalysts.