In presenting the arguments for high standards in recording we saw that sound recordings, unlike written records, contain no superfluous matter but that every detail is a source of information. In a book, a spot of fungus on a page will generally not hinder the reader and at worst may reduce the volumes commercial value, but the slightest damage to a sound recording immediately results in a loss of information. Its physical vulnerability dictates the precautions which we need to take if we are to ensure the preservation of acoustic source material.