Well i stained the back patio and it didnt come out very well. I basically taped off a Grid type pattern with 18" X 18" squares masked off with masking tape. Well the outside patio concrete is so rough and porous that the stain seeped under the tape ruining my well defined lines i wanted. UGH!!! My question is what can I mask off patterns with on rough concrete that will seal off the stain? Imagine some type of really thick gummy tape or something. Any ideas?