I have stored steam pasteurized substrate (straw, cardboard, and wood chips) after both 15 and 30-minute rolling boil. The substrate was pasteurized in glass jars with button tops. Once the jars were removed, I waited about 5 minutes before tightening the tops. Once the buttons clicked, I kept them in a relatively sunlit area and used them up to a week to two weeks later. A few that I opened, but did not use all of the substrate, I placed into the microwave with the cap, for about a minute. Removed the bottle and again tightening the cap. Once the button clicked, again I placed it in a sunlit area and used the substrate again. Using this method, I did not have any contamination. Be careful using metal in microwaves. Sometimes you can get away with it, sometimes you cannot.