In ancient Chinese both characters for k’uai tzu (quick ones) were written with the bamboo radical, suggesting the material with which chopsticks were initially made.
Senajā ķīniešu valodā abos hieroglifos, ar kuriem apzīmēja kuaidzi (’ žiglie ’), ir atslēga ar nozīmi ’ bambuss ’, kas vedina domāt, ka irbuļi sākotnēji tika gatavoti no šī materiāla.