Dub- cov tub ntxhais txiav cov ntaub qhwv, raws li lub npe qhia, muaj cov xim dub lossis tsaus nti - cov tub ntxhais muaj xim, sab hauv lossis ntawm qhov chaw. Qhov kev tsim no feem ntau cuam tshuam nrog cov khoom ntawm cov khoom siv lossis cov txheej txheem tsim khoom. Piv txwv li, qee qhov dub - cov tub ntxhais txiav tuaj yeem siv roj hmab lossis yas uas muaj cov khoom siv tshwj xeeb lossis cov khoom siv rov ua dua tshiab ua cov khoom siv hauv paus. Cov ntaub ntawv no tuaj yeem tig dub thaum ua haujlwm vim oxidation, carbonization, lossis ntxiv cov xim dub. Tsis tas li ntawd, qhov dub - tus qauv tsim tseem tuaj yeem yog qhov pom qhov txawv ntawm qhov pom, siv los txheeb xyuas cov ntaub qhwv ntawm qhov sib txawv thicknesses, hardnesses, los yog siv.
Hais txog kev ua tau zoo, dub- cov tub ntxhais txiav cov pads yuav muaj kev puas tsuaj zoo dua, kev cuam tshuam los yog kub tsis kam, nyob ntawm seb lawv cov khoom siv tshwj xeeb thiab cov txheej txheem tsim khoom. Txawm li cas los xij, nws tseem ceeb heev uas yuav tsum nco ntsoov tias tsis yog tag nrho cov dub - cov tub ntxhais txiav cov ntaub qhwv muaj cov txiaj ntsig zoo; lawv qhov kev ua tau zoo yuav tsum raug soj ntsuam ntawm ib rooj plaub-los ntawm- rooj plaub.