One of the things I am trying to do is tack fuse onto irid surfaces, and I have experienced inconsistent results. I like to make smaller "bubbles" prefused generally with clear but sometimes with colors in various sizes, from 3/4 to 1-1/4 inch in diameter. Sometimes, after going through the tack fuse schedule, the bubbles just pop off, leaving an indentation, while other times they stick. For this latest piece, I used a conservative schedule (maybe too conservative for what I'm doing, but this schedule suggested by Susan Green -- thanks! --saved the day on another piece, and I like to stick to what works), going up at 50/hr until 1000 degrees and then 100/hr to 1300, holding for 10 minutes. However, on a previous piece, I took it up to 1325 and held for 15, also with inconsistent results. Is there something about the irid surface that makes tack fusing more difficult? Is there a way to make the non-irid glass bits stick to the irid, yet keep the texture I want? I would hate to have to resort to glue, as my husband suggested! Thanks for any help?