When the Chopstix is fired to a smooth finish, it should look like a regular iridized sheet, but with markings on the surface. The stringers melt into the surface. The glittery texture disappears.
The sparkle that you describe comes from the texture of the glass, and the refracted light going through the clear stringers one way and through the sheet glass another. When the texture disappears (as in a full fuse) what remains is the interesting irid pattern. This is kind of subtle in the cold, textured sheet, because the texture of the glass catches the light, and the irid finish can be difficult to see well on a clear sheet. The main thing that the Chopstix (stringer) does for the fused sheet is to break up the irid coating in interesting ways. The thickness of the coating provides the color, and it is applied in a mist to the hot glass. The surface texture of the stringers on the blocks the mist in such a way that the irid coating deposits in a less regular way across the glass, and after fusing, you may see color variations and lines showing where the stringer was located as it disturbed the path of the mist.
I am sorry it did not turn out the way you expected. Firing it face down may cause the irid to look more glittery, but the stringers themselves may become less visible, as they did when you fired face up. It's worth trying, though! And you might try firing it layered onto different colors, just to see if that causes any pleasing variations.
Mary Kay Nitchie
Bullseye Glass Co.
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