Boiling up a bunch of purple cabbage is not the most fragrant way to spend time, but I was eager to see if I would get something red or purple.
What I started to do for all of my tests was to put four wool yarn samples that I had pretreated with alum into the "juice" along with a sample of yarn without any mordant. After simmering for about a half hour I took all the samples out, poured a smaller amount into a pot and added tin to the "juice" and added one sample of prealumed wool and one sample with nothing to create two different samples. I then went through the same procedure with the copper and the iron.
My first sample with the alum produced basically no color, a surprise considering the purple juice that was in the pot. Next I added tin which made a really pretty light slate blue, I was hopeful to get something, purple but only got a really light tan green with copper and barely a green gray with the iron. Again a bit disappointed, but again some nice color when looked at on their own.
The photo is not doing justice to the beautiful color obtained.