Leaf hops are usually added either to the boiling wort in the kettle, or for dry-hopping, to the barrel or keg. For maximum bittering, additions need to be made one hour before the end of the boil. For late-hopped character, additions are usually made about 10-15 minutes prior to the end of the boil. Dry-hopping additions are usually made in the keg and the hops remain in the product for several days or, in some cases, even until the product is consumed. The main advantage in using leaf hops is in the perception of using a completely natural ingredient. The shortcomings are handling, storage, variability and a small level of physical contamination have to be borne in the mind with this product.