Beautiful! I've cleaned these. Check the embroidery - it will probably bleed. I love Synthrapol - I use the Jacquard version. It holds loose dye in the water. I would do a cold water sink soak with synthrapol. After that, I would likely do Dawn blue dishwash liquid, with a dash more synthrapol. I would use synthrapol in every soak load until the dress is clean. And, then in the clean water rinse, throw some color catchers in. This is a very, very thin cotton, and will be weakened when wet. Also, the heavier points will likely be everywhere the embroidery is. In the last soak, while the water is still in the sink, shimmy a towel or sheet underneath so that you can lift the dress evenly. You can then blot it to dry, lay out in the bathtub, just to get enough water out of it to possibly put over a drying rack without straining the thin cotton. I was terrified on my first one, but have been emboldened by experience and mistakes. I buy Synthrapol by the gallon and highly recommend it for anything that you are unsure about dye bleed. I think the very thin cotton may be just as much of a challenge - be sure not to use your nails to rub out spots, especially when wet.
