Hello!
Maybe I can help you; my husband is also going to improve our painted house with serponit., it can be purchased at a company called Allt i Bruk AB, Arlöv. Our house was painted in the 1970s and back then it was bought from Ernströms, but they no longer market serponit. Allt i Bruk does not have all the colors, but white, which you and we are going to have, is available.