smear, rub, wipe, anoint
搽 centers on applying a substance by hand: smearing, rubbing, wiping, or anointing something onto a surface.
搽 combines 扌 (hand) with 茶 (tea), likely as a phono-semantic compound where 茶 contributes the sound and the hand radical indicates an action of applying or rubbing.
A hand 扌 using tea 茶 leaves to smear or rub a surface, as if anointing it with a tea mixture.
For タ, imagine rubbing a tar-like substance with your hand: tar -> タ, and you smear it on.
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