Cov khoom siv khib nyiab pov tseg, feem ntau yog hais txog kev sau los ntawm ntau qhov chaw ntawm lub zej zog, qhov sib txawv, tsis muaj teeb meem, qias tuaj ntawm cov khoom siv qoob loo pov tseg. Nyob rau hauv cov khib nyiab, muaj cov chaw ua lag luam thiab cov chaw ua qoob thiab cov khoom seem ntawm cov khoom siv yas, cov hnab yas, cov tshuaj cement, cov tshuaj tua kab, cov ntses cov tsiaj, khoom ua si, khoom noj khoom haus txhua hnub thiab cov khoom yas, xws li kev coj noj coj ua thiab kev twv txiaj, muaj qee yam ntawm cov ntaub ntawv muab tub lim thiab cov yas yas siv yas yas. Cov khoom tsim dua tshiab ntawm cov khoom siv no, ntxhov ntxhuav thiab khib nyiab pov tseg ntau dua.
Cov tshuaj cog qoob loo, feem ntau yog cov tuam txhab lag luam thiab cov chaw lag luam me me thiab nruab nrab, tiam sis puas yog cov khoom txawb ntawm kev muag khoom, los yog ncaj qha mus sib xyaw rau cov khoom, raws li ob yam khoom siv, yuav tsum yog kev xaiv qhov kev faib tawm, nruj tshem tawm ntawm impurities thiab roj , tuaj yeem siv cov ntaub ntawv coj los siv ua qee yam ntawm cov khoom siv sib xyaw.
Cov ntaub ntawv coj los ua ke dua, qhov zoo ntawm qhov feem ntau qis dua cov khoom siv dawb huv.
