had been sooting

• past perfect progressive

  past perfect progressive

  Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.

  of soot.
  soot

  noun

  a black, carbonaceous substance produced during incomplete combustion of coal, wood, oil, etc., rising in fine particles and adhering to the sides of the chimney or pipe conveying the smoke: also conveyed in the atmosphere to other locations.

Related Words

• ash
• grit
• gunk
• residue
• sediment
• smoke