Historical clue formulations

• Dye used in some ballpoint ink — 2019-02-22
• Certain red dye — 2018-05-14
• Cosmetics dye — 2014-11-22
• Biology lab stain — 2011-12-04
• Red dye — 2008-10-28
• Red stain in a lab — 2007-07-28
• Dye chemical — 2005-02-08
• Biological stain — 2003-01-03
• Biology lab stain — 2000-01-05
• Rose-red dye — 1997-07-27
• Red dye — 1994-10-09
• Red dye — 1994-08-14
• Red dye — 1994-05-15
• Lab stain — 1993-12-05