Hi, This is a bit of a vague question but looking for a bit of advice. Our house built in about 1983 has stone mullion window surrounds. We purchased the house in 2012 and all was decorated. Some of the mullions do cause problems internally with bubbling, cracking, white powdery looking areas (and in the winter they are running with water). We are about to rub down and redecorate in a couple of rooms and I came across your website when checking out breathable paints. I think it was ordinary masonry paint used before but I was wondering if there was a better product. Most masonry paint seems to be for exterior use rather than interior? Perhaps they just need redoing every couple of years anyway?