During this cycle, as the molecules keep crosslinking, hardness, chemical, thermal and strength properties increase until they reach their optimum levels. Normally, these optimum levels are considerably higher when high temperatures are used for curing or postcuring. With fast compounds, heat should be used only after room-temp. Heating, however, should be mild and slow, or even avoided, if distorsion of uneven thicknesses or damage to heat-sensitive component may be caused by higher temperatures. Viscosity is a deciding factor for liquids and pastes, flowing or thixotropic consistency, for blending fine or coarse fillers in, filling thin cracks, etc.
High viscosity is better for build-up, patching for coarse aggregates, thick adhesives, etc.
For thick castings or whenever curing is conducted at higher temperatures. Indeed, often surface preparation is the longest and most expensive part of the project. This subject should be treated separately, but a mention here is useful. Sandblasting, for instance, should be the first choice for metal, concrete and most surfaces. Several treatments are available for metals, plastics, etc.