I have one more thought on the 122 cotton interfacing talked about in October.  I used this interfacing on a collection of recycled ties that I had bought and used in a small quilt.  There was a mix of weights of silk and I used the interfacing on all of them.  It performed well on the light-weight fabrics, but made the heavier silk ties stiffer than I like.  In this case, a mix of interfacings might have been better - using my lightest interfacing (which I had little of at the time) on the heavier ties.