1. Khaws rau hauv qhov chaw txias, cua txias. Khaws kom deb ntawm qhov hluav taws kub thiab cua sov. Nws yuav tsum tau muab cais los ntawm oxidants, acids thiab alkalis, thiab tsis txhob sib xyaw cia.
2. Muaj cov khoom sib xws thiab cov khoom siv hluav taws xob ntau. Qhov chaw cia khoom yuav tsum tau nruab nrog cov ntaub ntawv tsim nyog kom muaj qhov to.