My husband hung the green waterproof type drywall in the new bathroom. After finishing the seams, I painted it twice with Kilz just for added protection from humidity and moisture of the bath. I painted it with 2 coats of the semi-gloss paint. After several days he wiped it trying

I have a building with a dark brown stain and want to change it to dark sage green color with cream on the eves. My questions are: How do I know if the original stain is oil? Do I need to use a solid stain to cover the dark brown?