Even this blot turned out to work just fine. I thought it was a failure; that there wasn’t enough alcohol in the wash and the colors were too harshly separated. But when I added a layer of veining over it everything came together.
I’ve also been finding that if I don’t plan anything out but just work freehand and do everything on the fly then, the pieces turn out much more interesting. This is true for both the paint wash layer and the veining.