I have a dented pot I bought intentionally for dying in. It was discounted because of the damage, which damage also makes it easy to spot that this is not one of my cooking pots, and my "spoon" is an old stick so I don't worry about the toxicity levels of my dye ingredients. Natural dyes can be just as toxic as chemical dyes. So even though I tend to go for natural dyes I still don't want my experiments mixing with my food.
The vinegar and sumac are both acidic enough to act as the only mordant necessary. Or so I thought. I was attempting to dye cotton this time too, but cotton clearly needs more mordanting. Coming out of they dye pot the cotton lost more than half its color in the first rinse, although the resulting pastel is not unpleasant.