Pressure cooker prep

Wash Petri dishes (optional)

If your Petri dishes have previously been used or have sat out in the open for long periods, wash them before beginning this process. You will sterilize the dishes later, but cleaning them beforehand to remove any possible residue or grime will help.

Using warm and soapy water, thoroughly wash the Petri dishes until all residue (if any) is removed. Then, use distilled water to rinse, ensuring you remove all of the soap.

Washing petri dishes

Wrapping other tools

While the primary goal is to sterilize your agar, you must also ensure that the other tools you will use later are sterile. You can achieve this by wrapping your other tools in aluminum foil and adding them to the pressure cooker.

Petri dishes and aluminum foil

Stacking and Wrapping your Petri dishes

For this guide, your Petri dishes are the only other items to sterilize. Stack your clean Petri dishes in groups of 3s or 5s and securely wrap them with Aluminum foil.

The foil prevents water from getting on and in your dishes and is an essential barrier against contamination.

Aluminum foil wrapped petri dishes and flask

Reusable Petri dishes

Before pressure-cooking your dishes, make sure they are reusable borosilicate glass dishes.