Historical clue formulations

• Clear plastic — 2008-07-22
• Clear furniture material — 2007-10-14
• Classic DuPont brand — 2007-05-12
• Clear cover — 2004-06-20
• Transparent plastic — 2003-07-28
• See-through sheet — 2002-10-13
• Trademarked plastic — 2001-04-09
• DuPont brand — 1999-01-17
• Like some paint — 1997-09-12
• 1937 DuPont invention — 1997-02-09
• It's also called Plexiglas — 1996-12-27