I have used Warm and Natural batting with no problem. What I do put a piece of batting between fabric in the microwave and set the timer for 3 minutes. I can tell right away if the batting will be a problem. The satin finish won't cause a problem and neither has the poly thread I have used without thinking. I make my bowls for family use and they know never over 3 min. Also it depends on the wattage of the microwave. 3 min at high wattage is much hotter then 3 min at low wattage. This is why I don't give or sale them. I always test the batting before using. I've had the same brand batting get burned in less then 2 min in one spot. A flaw or random thing in the batting may cause it to burn.