medium aging. Multi-piece corks have two or more pieces glued together. They are denser than single-piece corks, and are not good for prolonged aging. Agglomerated corks are made of cork dust and glue, and are dense, inexpensive, and not good for sealing wine for over a year. Technical corks are agglomerated corks with single pieces of cork on either end. Attributes Cork stoppers are moisture-resistant, are slow to deteriorate, they help wine age, and provide a waterproof seal. The stoppers are associated with a perception of high quality wine, especially as cheaper alternatives are common with lower-cost wine. Because of the cellular structure of cork, it is easily compressed upon insertion into a bottle and will expand to form a tight seal. The interior diameter of the neck of glass bottles tends to be inconsistent, making this ability to seal through variable contraction and expansion an important attribute. However, unavoidable natural flaws, channels, and cracks in the bark make the cork itself highly inconsistent. In a 2005 closure study, 45% of corks showed gas leakage during pressure testing both from the sides of the cork as well as through the cork body itself. A study conducted by PricewaterhouseCoopers and commissioned by the major cork manufacturer Amorim concluded that cork is the most environmentally responsible stopper, in a one-year life cycle analysis comparison with plastic stoppers and aluminum screw caps. Reuse Wine corks cannot be reused as wine corks due to bacterial concerns, but they can be recycled into many other useful objects such as corkboards, coasters, flooring and used for all kinds of craft projects. While many synthetic corks can be at home, natural corks can either be composted or recycled at specific stores. Companies partner with stores to accept used corks and recycle them into other products; ReCork is the largest of these companies in the United States. Corks can also be recycled through Cork Forest Conservation Alliance. Types Still wine Corks typically are in diameter. Lengths vary, usually based on length of time estimated to age the wine. Simple wines are commonly long, medium aging wines (the most popular size) are , and long aging or expensive wines are often long. Sparkling wine Sparkling wine corks are typically in diameter and in length. When pushed into the bottle, the corks are compressed to about 60–70 percent of their original diameters. The corks are held in place by wire