Well, for all inquiring minds who want to know: I got some low fire ceramic overglaze and tested it on some coil stock. It just disappeared, obviously too low fire BUT! There was an interesting side effect.
At first I thought the glaze worked, since I saw some colors.... but then I realized it was only where there was no glaze painted. I did some further experiments and found that by manipulating the speed and power, I could get different colors (dark grey, blue, green, faded red).
It doesn't look great, but might be of some use to someone for a project. It might enhance an artsy photo or drawing. Take a look at the pix.
cheers, dee