These shingles in Santa Cruz are about ten years old. This happens to be the west-facing side of the house that gets very little sun whatsoever. Although the shingles were filthy black before we began, they were the best shaped shingles on the whole house due to insignificant sun. Nonetheless.. we then cleaned with a cold water technique only and then of course began to apply Biowash Natural Deck Oil. This happens to be Cedar-Tone. GOOCH!!