I took her four glazes, and another four of my own and did my first "testing the waters" experiment. A firing with no extra cooling or holds, then five intervals of 100 deg F, starting at 2000 deg F. Slow in each of these intervals and a 1 hour hold at the bottom of the "window".
The results were not all that exciting, but it was a great learning experience for me. All of those glazes were near the bottom of their firing range for cone 6, one of those glazes was slightly below its bottom.
Once the glaze has frozen, things -- atoms and molecules -- don't move fast, so for all practical purposes, its useless to do designer cool and hold below the glass transition temperature for the "glass" which is the glaze. Glazes fired near the bottom of their firing range are fired only a tidge above their respective glass transition, and one doesn't see much change.
That said, the glaze that was underfired to the point of having the sandpaper - sandblasted - look of a not quite melted glaze in the initial calibration (no extra anything) quasi matured in several of the cool and hold firings. I write quasi matured as a close examination shows bits of glaze not firmly attached to body.
Here are pictures of the two glazes from this experiment that show color progressions. They are Cooper 394, and cooper 419. I made some small changes in these glazes. I added bentonite, and in cooper 419, I used albany slip in place of one of the clays he recommended.
More details on request.
There are 6 firing protocols. These tests were all fired to a hard cone 6 on a cone 6 B-mix variant in oxidation.
The first block of glazes shows the results of the 6 firings of cooper 394. The second block of glazes shows the results of the same 6 firings of the glaze, cooper 419.