Karetot 20: Un/Intentional Lighting and Extinguishing Charcoal on Shabbat

Today we examine the prohibitions against lighting a fire and extinguishing a fire on Shabbat: are these actions punishable by karet if they are done unintentionally?  The Gemara quotes a baraita where the rabbis discuss one who might bring two sin offerings because one put out upper coals and kindled the lower coals.  Was only one of these intentional?  Was this a blacksmith who needed the lower coals to be kindled and so he put out the upper coals knowing that this would set the lower coals on fire?  Is he liable or exempt from both sins?

Steinsaltz teaches us that charcoal was often used to fuel very high temperatures.  Charcoal is made by heating wood until it is completely carbonized - carbon and inorganic ash remains.  Bricks are put on the charcoal to raise temperatures even higher by depriving the charcoal from oxygen.  The blacksmith in this case example would have wanted to use the large pieces of wood at the top and not the smaller pieces of charcoal at the bottom.