I had the opportunity to handle some silk batting at a show a couple of years ago. OMG! I would love to use it! As many have said, cost is an issue. I believe in natural fibers to the extent possible. I use W&N 100% (athough it probably isn't) cotton for all of my quilts. Natural fibers breath. Summer/winter, doesn't matter. I was researching parade uniforms at one point and the ladies in the group thought I was nuts for suggesting wool for summer parades. They are so sad they went with polyester pants later on. They are HOT! One of these days I'll get to use the silk.