I'm very disappointed with the coverage 2 coats of fence treatment so far on my very long very old fence, especially since I spent most of my garden budget paying someone to do it-he tried but it just disappeared. The rainwater is beading up well so something is there, but the colour is too pale. Now I have to try another coat myself, I wondered if those rollable ones are any good for coverage- any tips please anyone? Should I try to mix some black in to get the dark brown I want?