I don't dye but for those following this thread who do or are just getting into it, here's an angle to consider. I took a class with a well known, published quilter. Her husband is a "closet" dyer and he takes his work very seriously. He wasn't getting consistent results so he checked with the city water department. It seems that they change the chemicals in the water seasonally. There's a change for summer and again for winter. This affects the dye results. He has to adjust for the changes and he now knows when the changes occur so he can dye accordingly. Interesting!