unbleached cloth; unbleached colour (color)
unbleached; undyed
「生成」 has another reading with different meanings.
生成の布で鞄を作った。
I made a bag out of unbleached fabric.
この生成の色合いが好きだ。
I like this natural unbleached tone.
生成のシャツは染めずに着てもおしゃれだ。
An unbleached shirt looks stylish even without dyeing.