@Jules, I tried using that Krylon easy tack spray you once recommended to me for re-stickying the Silhouette mat. Sprayed on two sheets of regular paper and used to mask. Seems to work, prevents the smoke discoloration, although there is still charring on very fine features from the power setting I need to burn through the whole stack.
I bet one could even use this for a quick and dirty mask on wood, since you can adjust the tackiness by spraying both parts.