Yesterday, I dyed just about 4 1/2 ounces of wool with elderberries. I had about 1 pound of berries with which to make the dye bath. I mordanted the wool with alum and cream of tarter.
I added about a tablespoon of vinegar to the dyebath. I read that adding vinegar to the elderberry dyebath will strengthen the red/purple color, and adding salt to the bath will turn it more toward the blue hues. I was going for the red/purple. I knew that the final color would be much lighter than the bath color, and I didn't want the blue hue to end up more of a pale slate-blue/gray on the fiber.
I almost-simmered the mordanted wool in the dyebath for an hour and then took it off the heat and let it sit in the bath overnight. This morning I rinsed the wool and it's now hanging to dry:
On the left is almost 1/2 ounce of wool from my Christmas fleece that I combed up during demonstrations last weekend at The Crooked River Fiber Fling. On the right is 4 ounces of superwash Bluefaced Leicester.