Trim a quarter inch from the end and immerse in tepid water. Let drain for another 5 minutes. Store covered in a Cambro food storage box and place in the cooler immediately after draining. Water absorbed by the leaves will quickly turn the temperature of the cooler. This will cause the leaves to go into shock and become strong and crisp with a high water content. Place leaf lettuce in a Cambro food storage box to prevent the product from becoming limp from dehydration or yellow from ethylene gas.