Loss of gloss
Cause
General loss of gloss caused by moisture or gases coming in contact with the wet or semi-set film during drying. This is particularly noticeable on exterior surfaces such as window sills when the work has been completed late in the afternoon or early evening, when the ambient temperature falls, and dew comes in contact with the surface. Internally, in areas such as kitchens or bathrooms when there is an increase in humidity, i.e. steam before the coating dries.
Also see: Chalking.
Remedy