Here from Dulux themselves:
ICI Paints has avoided using the term "microporous" to describe its products, regarding it as a somewhat misleading sales gimmick, because nearly all paints and stains offer some protection against rainwater, and all paints and stains will to a greater or lesser extent allow moisture vapour to pass through them in either direction.
ICI Paints has avoided using the term "microporous" to describe its products, regarding it as a somewhat misleading sales gimmick, because nearly all paints and stains offer some protection against rainwater, and all paints and stains will to a greater or lesser extent allow moisture vapour to pass through them in either direction.