What To Do When Rain, Mud, and Blood Make A Mess Of Your Halloween Costume

As part of my flea-market mermaid costume, I wore an old silk nightgown, then spent a rainy evening treading all over the bottom hem. I have already given the nightie a wash with mild laundry soap in cold water, which took care of most of the dirt, but it’s pretty ground in along the seam. Think it can be removed?