Thank you for your responses/suggestions. I spoke with Xante technician who confirmed that only Glassine and Corn Silk are the only materials that will not melt on the fuser. Just an FYI, I was able to run my existing envelopes on a Xerox Qube printer and they ran OK. However, the production is significantly slower than the Illumina and the pressure on the rollers gave some minor wrinkling on some, but not all of the envelopes. I do believe that the digi-clear are twice the price of the current envelope I have in stock. It will be worth it to run on the Illumina. Again....Thanks.