You're right, but so am I. The same month that Silver Lake came out, I was at her home. I had tried it out and took some of my test beads up with me because I loved how it silvered up and became mirror-like in a reduction flame. We talked a bit about it (and a whole lot of other stuff) and she told me that she make it into a blend so that what happened with Raku wouldn't happen again with this (her finding a nifty something and folks buying it elsewhere). Yes, it is a blend - there are little bits of blue frit in there. The label says it's a blend and it's listed in the blends in her PDF document that he had available on her website with all of her frits on it.
Hey Val....
Snapshot of the pdf document she had
Close-up of the label
Picture of the original frit I had
And also, to some extent, all of the Zimmerman whites did the same thing - at least the three I tested did.