Cooking was initially a two-step process. Sealed cans were cooked in a hot water bath until the lid started to expand outward. The cans were removed and a small hole was punched in the lid to release the steam. The hole was immediately filled with lead solder. The second cooking was completed in large pressure cookers called retorts. The retort cooked the fish at 115 degrees Celsius (240 degrees Fahrenheit) for 1.5 hours. After the vacuum sealer was introduced the product was cooked fully in retorts in a single step.