煙子 / 烟子

えんし

Soot black is a pigment relative of 墨色; period records count it as enshi, distinct from the sumi ink stick.

Tobunken's 彩色DB records 煙子/烟子 (lamp black / soot) counted by sheet in Nara-period documents.

Lamp-black pigment context only. It is documentary attestation, not a measured value for 墨色.