Well, this shed at Southwold was very recently refurbished and tarred. But, black as tar can look when it's new, it's not a good idea to have it like that on a model. It just looks too black and too clean. Even on a recent tarring, there can be a hint of silvery wood behind the black and in order to get that effect I bought the micro pot of silver grey mentioned in the post above and painted the shed with that first, then, when that had dried, I used some back gouache from the palette, softened up with water and went over the silver, taking a little of the black off with a cotton wool bud. Seems to have worked quite well.
I also represented the roofing felt with scale width strips of 1000 grit wet'n'dry paper. Unfortunately the clear general glue I used in the absence of proper Evo-Stik as used to be in a tube before they changed the formula, refused to really work on the paper and is still lifting, so I may yet have to mask the roof from stray glue and poke something stickier between sheets. However, the basic impression is good and I am satisfied with it.
All the shed needs now is it's door fitting with hinges and lock and painting faded blue and a window frame and glazing fitted.
I'm still trying to work out how to represent netting so that I can produce lobster/crab pots as I need a fair few of those.
I might have a bash at a rusty old winch next.