Definition and Description of Aesthetic Surface Changes

Dirt Pick-up

The term dirt pick-up describes the soiling caused by foreign material other than microbiological organ­isms that is deposited on or embedded into a sealant surface. The soiling is generally caused by the accumulation of airborne particulates on the sealant surface.

Microbial Growth

The term refers to the accumulation and colonization of microorganisms on a sealant surface.

Surface Cracking/Crazing

The term refers to cracks formed on a sealant surface as a result of environmental ageing. Surface crazing is only observed with organic sealants.


The term refers to the whitening of some organic sealant surfaces with weathering. The whitening is caused by the degradation and erosion of organic polymer, which leads to increased roughness or porosity of the sealant surface. The early stages of chalking are marked by a loss of surface gloss and color. Some sealant formulations weather so badly that all organic material leaches from the surface, leaving behind nothing but the inorganic fillers, typically calcium carbonates, hence the term.