|Bodice is a bit darker than the skirt!|
(1) Not enough dye for the fabric, or too much fabric in the pot.
(2) Too much acid, too early?
After mulling my choices for dye, I settled on the Procion dye, which works best on plant fibers such as cotton or linen, but will work on silk if you add vinegar to the dye bath. I thought that would be fine, because I would dye the lace and silk separately, and I didn't want to get two different dyes and risk having them clash. Unfortunately, I forgot that the lace was cotton on a nylon mesh. The nylon needs the acid, too. Oops.
After several different dye/chemical/temperature combinations, I found a really nice color that dyed both the cotton and the nylon. Heating the dye bath and adding vinegar (fixative for nylon) about 15 minutes after adding the fabric, then adding soda ash (fixative for cotton) gave me a perfect color. If I didn't add the vinegar, then the mesh didn't take the dye.
Using Rit would have dyed the cotton and the nylon about the same color, but I know from experience that it would fade quickly. And continue to fade. And maybe fade directly onto my skin. And maybe ruin your washing machine (true story). I don't like to use Rit.
I still haven't figured out what caused the irregular color on the lace, though. Maybe I had too much fabric for the size of my pot? It was a lot of fabric, and the cotton has an irregular surface.
The silk took the dye perfectly. I loved looking at this while I was sewing the dress and just wished that my main fabric had come out this nicely. Ignore my shadow in the bottom of the picture -- it's really all the same beautiful color all over.
My interest in dying fabric hasn't faded...especially if the fabric is silk. I will be more judicious about what fabrics or combinations of fabrics I use in the future, but I'm still fascinated with the process of creating the perfect shade for my projects.