Thank you so much for the input, everyone! I’ve never worked with silk before, and didn’t even know you could wash it before sewing with it. I had already made the dress, thinking that (similar to cotton) I would just be able to iron out the fold lines later. I did try a little bit more heat with steam. That seemed to help a little, but didn’t completely get rid of them. And then, I tried to squirt a little bit of steam onto the fold lines (in an attempt to duplicate steam ironing, ha!). That only resulted in some particles from the iron squirting onto the dress. These lines were stubborn.
Btw, Lizabeth, the piece was folded pretty small, so I couldn’t try to strategically place the pattern pieces to avoid the fold lines.
In the end, the fold lines remained, but although I could totally see them, my husband said he couldn’t tell. And when my daughter wore it, it was hardly noticeable. Especially after she wrinkled it all up. 🙂
Here’s the dress if you want to see what I’m talking about: http://www.flickr.com/photos/60650466@N03/7284735052/in/photostream (I was originally planning to make the o+s bubble dress, but changed my mind at the last minute.)