Differences in when you add vinegar?
  • Some people say to wet the fiber/yarn with a water/vinegar mixture. Some say to add it to the dye before pouring it on the fiber/yarn. Still others say to add it after you've added the water and dye together. What happens with each--is there a difference in the results? If so, what's the difference? :confused:
  • Once you understand the purpose of adding an acid to the dye-bath you'll be able to make the determination, or at least devise a simple test of your options.
    The dye class "acid" dyes is named such, not because the dye itself is acidic, it is because one uses an acid in the dye bath when using the dye. When you put an acid in the dye bath containing a protein fiber like wool or silk (and Nylon) the fiber takes on a positive charge (+). The dye molecule (and this is the confusing part) itself has a negative charge (-). Unlike charges attract each other. In the dye bath you have negatively charged molecules being attracted to the positively charged fiber. Therefore you have created an enviroment where more dye moves, and stays, on the fiber. The result is the fiber dyes darker, and the dye bath "exhusts" meaning, in an ideal environment, no dye is left in the dye bath after all is said and done.
    I always tell dyers to add fiber (wet or dry) to the dye bath, then acidify 5 or 10 minutes later.
  • Nice, clear answer! Thank you!

    So of course I have more for you.

    I've been dyeing wool lately with MX dyes. Dharma says to use quite a bit of salt before adding the vinegar. Does this affect the charge? Or is it some other mechanism.

    Also, is this why the colors that are mixtures are supposed to "shift" when you use MX dyes on wool?
    Thanks So Much
  • Hi,

    Some dye recipes call for the same weight of salt to be added as there is fiber in the bath. Salt forces the dye from the bath = water into the fibers. Technically the more salt the deeper the shade achieved.

    The shift of color that you refer to, can be caused by a mix when one of the colors has a greater affinity to the fiber type than the others. This is pronounced in Chocolate Brown MX for instance that can come out rose colored on silk.

    By far the best dye for wool in my opinion is acid dye.