The color appeared to be a deep rich walnut brown, almost black.
We were away the last two days visiting relatives for Thanksgiving. It is good to be back home, and I couldn't wait to see how much more color had been absorbed. After rinsing, though, it is a much lighter color, almost what I would describe as "chestnut". I hung the skeins on the patio to dry in today's brisk breeze. They should be dry by tomorrow.
I really was expecting a darker color, but I do like the color that I got. Since I am pleased with the color, and the dye vat is far from exhausted, I will also wind some sock yarn off the cones and use more of the same dye vat - it will be dye lot #27. I will not pre-mordant the sock yarn wool, to see if I achieve a different color. For dye lot #26 I used 1 quart (1/3 of total) of leftover alum mordant from previous (goldenrod) dye lot as a pre-mordant. Alum is supposed to "brighten" the color. Black walnut is not supposed to need a mordant for color-fastness. If I get serious about this, I will need to start being more precise about these recipes. Every book I have ever read on dyeing mentions record-keeping as very important in order to be able to achieve repeat colors.