Old debate. To test out what would happen, I cut out a square of my silk, rinsed it in warm water with a smidge of Soak, let it dry, and compared it to my original fabric.
Definitely some changes there. The washed square looks like it shrunk just a little bit lengthwise. It also shows more texture than the unwashed silk.
This wasn’t enough to stop me from washing the rest, since I know I’ll be dancing and sweating in this. I figured having been in water once would make it less vulnerable to water spots if I needed to spot clean.
This turned out to be a very good plan, since I spilled a whole bunch of water from the iron on the skirt when pressing the french seams. No discernible damage from that. Woo!