Fast-forward a month or two: While in Argentina, I met Laura who was quite familiar with this stuff. My new friend gave me a lesson in how to use the powder. (Though she uses it in an entirely different application -- making edible figures for cake decorating.) The process includes sprinkling it over a bowl of very hot water and to make a fantastic gel. Our beautiful bookcloth finished the covers for the journals we put together at her kitchen table.
Lately I have bought little 1/4 yard cuts of fabric and which each produce enough bookcloth for 3 books. The process requires a smooth shiny surface (a sheet of glass or smooth countertop), a piece of backing paper larger than the fabric and, for my purposes, a piece of cotton print fabric 9" by 15" or so, and the pre-mixed gel. The gel is smeared onto the paper to moisten it. The paper is set aside. Then the cloth is laid face-down on the smooth surface and coated with more gel. It's then covered with the paper (wet sides facing) and smoothed with a roller. Left overnight, the paper has dried, the fabric is "paperbacked", and the unveiling is just very enjoyable. It lifts off with a satisfying ripping sound, revealing a lovely workable structure, ideal for wrapping the cardboard for book covers.
See Sage Reynold's instructive video for my original source for this technique._
I am delighted with the results I get. It makes such great cover material - perfectly smooth and lovely to work with.