varnish
杶 centers on a tree or wood product used for varnish, likely referring to a specific tree whose sap or resin is used as a coating.
杶 combines 木 (tree) with 屯, which likely contributes the sound. The character probably names a tree species used for varnish.
A tree 木 with a squat, solid right side 屯 like a can of varnish: the tree provides the varnish.
For チュン, imagine a tree being varnished in a single, smooth motion that makes a soft 'chun' sound as the brush glides over the wood.
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