I wanted the shingles on the dollhouse to look like slate instead of wood, since that was a common material to use for roofing at the turn of the century. The wooden shingles that came with the kit had a nice shape already.
Slate shingles don't have to be squared off. In fact, if you look at old Victorian homes, the slate would often be chipped away using a mallet prior to roofing, producing fish-scale or octagon shaped shingles.
I started with two packs of Grey Shingle dye for 2000 wooden shingles, which I mixed in a ration of 3 cups for the two packages.
The instructions for dying the shingles seemed overly complicated, involving a netting to hold the shingles inside an upside-down jug and repeatedly pouring the dye over them. Why in the world you would want to do it that way, I have no idea, unless it just doesn't make enough with one pack to cover 1000 shingles, even in batches. We used a simple process instead that worked very well.
We mixed the dye in a small tupperware type container that was fairly shallow, and then we simply put a couple handfuls of shingle into the dye mix at a time. Using latex gloves, we would swish the shingles around to make sure they were thoroughly coated and then let them soak for a couple minutes per batch. We moved each soaked batch into a planting tray (the kind left over after you buy flowers from the hardware store).
I did follow the dye packed instructions to rake through the shingles over the next few days as they dried. The shingles dried about 40% lighter than what they look like wet, and still looked distinctly wood-like since the dye picked out the wood grains. I did have enough dye left over to run the shingles through a second time, but I knew it still wouldn't achieve the slate-like look I wanted.
Fortunately, there is a spray paint called Chalkboard which gives a slate like matte finish when sprayed on. I applied two light coats, which was enough to hide the wood grain. The dye was still worth doing, because all of the shingle edges were dark, and I didn't have to worry about spraying them as a result.