Totally forgot......fire to 1000 c hold for 10-15 minutes no vac... ....this will lighten the shade ... I guess it burns off some of the sintered coloring ......If this doesn't work, try the cutback,,, and glaze higher... I've learned the more you fire fcz, the lighter it gets.......May not be true for all fcz, but true on Bruxzir....
If its real dark, your screwed..