Comparison of Dye Strength

The dye I have now is over two years old. Some of the colors don't have the kick they used to, particularly the yellow. When I get new batches of dye in I will conduct tests to determine how strong the dye mix needs to be to get vivid colors. My approach to this will be to have a series of small bottles with dye mixed at various strengths. I will keep a record of each shirt I make showing the pattern, like spiral for example, and what strength of the different colors are used.