Step 2: Surface clean and autoclave your glass petri dishes
I like to wrap my petri dishes (with lid) in aluminum foil, and also to pre-sterilize my Erlenmeyers just for storage purposes. This covering allows you to maintain a sterile environment within the wrapping when you take it out of the pressure cooker, but won't prevent the steam from entering and sterilizing your equipment. REMEMBER, you NEVER want to autoclave a container with a screw top lid on it. Remove the screw top lid from your slant tube and wrap it separately in foil. The mouths of Erlenmeyers and the slant tube can be covered in foil. Autoclave these safely as per previous instruction (pressure can be 'quick-released' to speed up the process, ONLY if you are using 100% borosillicate glass materials), but be patient. This is a preparation stage and can be done well in advance of actually making solid culture medium plates, if desired.