I have a nice fence that is about 3 years old. The fence was watersealed and it gave it a "stained" look. The fence is starting to turn a black/grey color because the waterseal is fading. I want to bring back the stained look but don't know if I should sand the wood and then spray a waterseal or just spray the waterseal. Also what is the best waterseal to use? Thanks in advance.