Wissmach Irid

[Jerrwel]

I've been using Wissmach 90 for the last year or so and perhaps have an insight others might find of interest. Or this might just be a 'well duh!' comment. The published information about their irids is that irid initially fired down is brilliant color, fired up is reduced color, and capped disappears. What I have found in firing irid down and refiring is that the color remains virtually unchanged when refired irid up and the color still disappears if capped. My process temp was 1485F (higher than I normally fire) and the irid was a little rough to the touch.