what kind of brush should I use to stain a very porous log? It has many groves, pits and uneven places on it. I used a regular paint brush and i had to go over and over , back and forth up and down to get it completely coated. The stain is a lighter stain than what is on so I want to cover completely. Oh I am a new log cabin owner, the cabin is 40+ years old and in good shape. Thanks Bruce