Si Collection, Middle Volume
Radical: Fire (huǒ)
Tai
Kangxi strokes: 9
Page 668, Entry 28
Pronounced tai.
According to the Explaining Graphs and Analyzing Characters (Shuowen), gray soot is coal soot.
In the Collected Rhymes (Jiyun), sometimes written in a variant form (tai).
Also, according to the Collected Rhymes (Jiyun), pronounced tai.
According to the Jade Chapters (Yupian), soot is smoke and dust.