The light spots on the backside is dappled sunlight. It's actually a much more even distribution of color than it appears above.
Using my Candiotic Tables, I picked a color, weighed the dress/fabric, calculated how much dye I would need and mixed up the colors. Good practice!
Here's a detail shot to show the variation in the colors.
It's really quite subtle, but pleasing. I got this by scrumpling the dry dress up into a plastic bin, adding the dye solution, and then the soda solution about 10 minutes (or more) later. I was able to take advantage of the hot weather this summer and batched it on the driveway for a day. Worked great! The bin would not have fit in my dye kitchen microwave. So mental note : Dye dresses and clothing (larger pieces) in summer to take advantage of the heat. The dress came out very well--with complete coverage. Although in my mind, I was thinking they'd have more color separation. Upon reflection, I should have pre-soaked the dress in soda solution for the color separation effect as demonstrated in the color swatch samples.
Upon further reflection, when I've done the parfait dye method, I don't use so much dye. That way, some places on the fabric come out white, adding to the texture.