Thanks, gals! Although the silk is quite a bit heavier than, for instance, a silk blouse, I think you're probably right about stabilizing the whole triangle. I hadn't thought as far as the (eventual!) quilting. I might do a few test squares to see what works best.

The fabric came from my cousin, who purchased it on a recent trip to Japan. She's an artist and art professor who works primarily in "found" items - turning things that other people would normally throw away into art. I once attended one of her shows, and afterward sent her an e-mail stating that, yes, she's still an artist and I'm still an accountant. Hence her challenge to me to use my quilting creativity and her "found" objects in a project. I'm going to a retreat this weekend, and figure the endless repetition of sewing triangles together will allow me to both get something accomplished and yak with my sister and other retreaters.

You really want to stabilize the silk!!!! If you are going to mix cotton and silk in the halfsq triangles I would surgest you stabilize both and not just only a strip at the seamallowance. Why?? Silk is a difficult fabric to work with when its not sabilized..and when you mix cotton/silk you want to make the "quality" of the 2 fabric as alike as you can. Also...when you are done with the quilttop and want to quilt it..the silk will give you a hard time if not stabilized!
It seems like a lot of work though, but I bet it will look gorgeous in the end!

I can't say I ever did this but my thoughts are that if you interface the whole silk triangle it will make it equal to the fairly stiff cotton as it is.
Karen

As a gift/challenge, I was given a bag full of half-square triangles of Japanese silk tie fabric. I have purchased a good quality fairly stiff cotton to use with it, but am looking for ideas on how to proceed. The finished blocks will be about 4 inches square. I plan to use a lightweight interfacing to help stabilize the longer bias edges, but can't decide which fabric to interface, i.e. silk, cotton or both, and whether to interface the whole triangle or just an inch or so along the edge. Any thoughts? Thanks!