Cov qauv txheej txheem: cov raj-puab, cov khoom loj, tsis muaj kev sib chwv, muaj cov khoom siv du, stains, tus kheej-nplaum ntaub qhwv yuav tsum yog tus kheej- Cov plaub hau nplaum, elasticity, tsis-staining plaub hau, daim tawv nqaij, ris tsho hnav ris tsho.
Cov tau txais daim ntawv thov: siv rau kev hnav khaub ncaws hnav lossis ceg tawv los muab cov quab yuam khi ua si lub luag haujlwm ntawm kev qhwv thiab kev txhim kho.