Black Agar

Step 1

Begin by boiling water.

Step 2

In an autoclave-safe glass container, add 5g of agar-agar, 7.5 g of light malt extract, and around 1 g of activated charcoal.

Step 3

Carefully measure 250ml of the boiling water and pour it into the glass container to combine with the dry ingredients.

Step 4

Place a filtered lid on the mixture, then shake or swirl the mixture until the dry ingredients begin dissolving.

Step 5

Use foil to cover the lid. This prevents moisture from entering that agar mixture.

Step 6

Prepare your and securely place the mixture inside a pressure cooker or autoclave. Seal the lid and cook until the pressure cooker reaches 15-PSI.

Step 7

Cook the agar for 45-minutes after the pressure cooker reaches 15-PSI.

Step 8

Once the time elapses, turn off the heat and allow the pressure cooker to return to zero PSI before cracking the lid open. When ready, remove the agar and place it in your work area.

Step 9

The agar is ready to pour once it reaches a temp between 116-122°F (46-50°C).

Step 10

Now, you are ready to pour your mixture into petri dishes. You must follow the sterilization protocol for the next part. It is a good idea to prep while the agar mixture is cooking.