I love hand sewing binding and discovered how well silk thread does with it. I am a big Aurifil thread fan. I use it for piecing, applique, and some machine quilting. But, I have found that silk thread doesn't fray at all and doesn't twist like cotton threads do. I got the silk thread from Joann Fabrics. They don't have a huge color selection, but the thread melts into the quilt.
Take care,
Cathy