The design and construction of digital speech processing systems to serve as an aid to the hard-to-hearing

A removable plastic film is attached to the mold die whenever the mold dies needs to be cleaned. Using such a film, the problems with cleaning the mold dies are avoided because whenever the mold dies need cleaning, the film may simply be placed over the mold and simply peeled off to remove all contaminants from the mold. The contaminants stick to the peeled off film and so are removed from the mold.