Pour agar into Petri dishes

Stack your Petri dishes

To help prevent condensation build-up, stack your Petri dishes in groups of 3 or 5 while pouring agar into them. Moisture might have built up during sterilization, making them slippery, so be careful while stacking them.

Slowly pour the agar

First, remove the aluminum foil and poly-fil from the flask.

Using your non-dominant hand, lift the top of the bottom dish and all the dishes on top, exposing the bottom-most dish's underside. Then, grab the flask with your dominant hand and slowly pour a thin agar layer. The layer should be about 1/8 inch (3 mm) thick.

Lifting dishes for pouring

Pouring agar

Work your way up the stack of Petri dishes slowly and under control, adding a thin layer of agar.

Pouring agar into the top dish

Cooling down

After pouring agar into all your dishes, give them an hour or two to solidify before moving on to the next step. It's common for condensation to appear on the top of the lids as they cool.

Stack petri dishes and allow them to solidify