You quilters are awesome with your responses. I knew I could find the answers I needed here.

I've seen silk batting, it's recommended specifically for silk quilts. :) Was thinking what a gorgeous quilt that would make!

I love silk, but never made a quilt with it, only garments. It can be a bit slippery to sew and likes to ravel, so bigger seam allowances than for cotton would be best I think. And yes I definitely do hand-wash silk. If it's upholstery fabrics I'd probably want to test for washfastness first, the colors might bleed.