Measure 37 g of pre-mixed LB-agar powder per L molten agar you'd like to make. The precise mass you measure out will be based on the number of plates you'd like to pour.

Transfer the LB-agar powder you've measured out into an appropriately sized bottle for autoclaving. We make 400 mL of agar in 1 L bottles and 200 mL of agar in 500 mL bottles. The extra empty volume is necessary to prevent your molten agar from boiling over in the autoclave

Cover the opening of the bottle with its cap or aluminum foil (but do not make an air-tight seal!) and tape the bottle with autoclave tape. The autoclave tape will darken during the autoclave process if your sample has spent at least 10 min at 121 ℃. Use lab tape to label the bottle with your initials, the date, and the bottle contents. This will clear up any confusion later if your forget your bottle in the autoclave.

Prepare your antibiotics. Prior to adding your antibiotic to the molten gel mix, you should create a 1000x stock solution.

Partially submerge your molten gel-mix in the 60 ℃ water bath.

Light the flame at the plate pouring station and dilute your antibiotic into your ~60 ℃ molten gel mix using sterile technique.

Swirl the agar bottle to ensure even distribution of the antibiotic throughout the agar.

Open one plate at a time next to the flame and begin pouring. Measure your desired amount of agar with a pipette for the first plate to get a good idea of what that volume looks like in your particular plate.