It is a 2 part polymer that can be either spead out on top of the water or incorporated into the soil before the pond fills, and it is used to seal leaking ponds. Send teehjaeh57 a private message about it and how it works. That's where I got mine.
I'll look into that more. I didn't realize there's a 16 page discussion about it on the forum when I asked what it is. I was figuring on trucking in clay when the time comes, but this Soilfloc might be a better option.
