Historical clue formulations

• Burnt chimney stuff — 2026-09-20
• Flue symptom? — 2025-01-15
• Santa's coat? — 2023-02-18
• Emissions concern — 2021-11-05
• Chimney buildup — 2021-11-01
• Pipe buildup — 2021-08-26
• Santa's coat? — 2021-01-12
• Chimney coating — 2020-11-17
• It appears in stacks — 2020-08-15
• Annoyance for Santa — 2020-03-01
• Stain on Santa — 2019-11-15
• Flue buildup — 2019-07-16
• Flue problem — 2019-04-06
• Chimney buildup — 2017-10-23
• Chimney sweep's target — 2016-11-09
• Shade of black — 2016-07-28
• Fossil fuel residue — 2016-03-13
• Some air pollution — 2015-12-31
• Fire proof? — 2014-12-14
• Diesel discharge — 2014-01-25
• Flue problem — 2013-12-14
• Chimney sweep's target — 2013-07-09
• Shade of black — 2013-06-30
• Shade of black — 2013-02-28
• Chimney black — 2013-01-14
• Santa's bootblack? — 2012-12-23
• Chimney sweep coating — 2012-10-29
• Sweep spots? — 2012-10-06
• It's found in stacks — 2012-04-24
• Lampblack — 2010-12-26
• Blackener of Santa's boots — 2010-09-21
• Chimney grime — 2010-03-08
• Film about a furnace — 2009-12-05
• Burning evidence — 2009-10-09
• Lampblack — 2009-02-10
• Blackener of Santa's suit — 2008-12-03
• Chimney buildup — 2008-09-29
• Symbol of blackness — 2008-09-13
• Stack buildup — 2008-08-09
• Some particulates — 2008-05-15
• Symbol of blackness — 2008-03-16
• Symbol of blackness — 2007-06-14
• Target of a sweep — 2007-05-18
• Chimney sweep's target — 2007-05-07
• Dirty coat — 2006-10-22
• Lampblack, essentially — 2006-07-19
• Shade of black — 2006-05-20
• Sweep's schmutz — 2005-09-13
• Epitome of blackness — 2005-08-04
• Pipe residue — 2005-03-20