I have textured walls that I would like to paint sections of. In the past, the darker color would run under the depressions in the wall under the blue painters tape. I have heard that I can apply a clear substance before along the painters tape to fill in depressions before painting. What do I use?
You could carefully rub some clear paintable caulk along the edge of the tape to seal it from bleed through. Another option is to use <a href="http://www.painters-toys.com/frogtape.html" target="_blank">Frog Tape</a>. The edge of Frog Tape swells a little to block bleed through. This works on smooth or semi-rough surfaces, haven't tried it on rough textures yet.