Ua ntej tshaj plaws, hauv kev xaiv ntawm cov ntaub ntawv raw, huv si degreased paj rwb yog siv. Cov paj rwb dauv yog hais txog cov paj rwb uas tau siv tshuaj kho kom tshem tawm cov rog. Nws yog qhov yooj yim dua rau nqus kua dua li cov paj rwb zoo tib yam. Nws yog cov khoom siv huv thiab tseem siv los ua nitric acid. Nws yog ua los ntawm cov paj rwb nyoos tom qab tshem tawm cov lus sib dhos, ua kom zoo dua, ua kom tsis huv, ntxuav, ntxuav thiab ziab. Cov paj rwb dauv qhuav muaj hydrophilicity zoo vim tias nws tsis muaj roj nyob rau saum npoo. Nws tuaj yeem siv cov tshuaj tua kab tsis zoo paj rwb kom ntog hauv 75% cawv. Cov paj rwb tsis zoo yuav tsum tsis muaj ntxhiab, tsis qab, tsis muaj xim, nrog cov dej zoo nqus, mos thiab xov paj dawb, dawb thiab elastic, yooj yim rau stratify, tsis muaj teeb meem impurities xws li acid thiab alkali, thiab nws cov khoom zoo yuav tsum ua tau raws cov qauv kev tsim los ntawm Ministry of Kev Noj Qab Haus Huv. Cov txheej txheem kev tsim ntawm skimmed paj rwb thaiv lub cev yog kom xaiv cov khoom zoo zoo ntawm cov paj rwb skimmed, txhaj cov tshuaj hnyav tshwj xeeb rau hauv nws, rhaub nws hauv dej npau npau, tom qab ntawd txias nws rau kev ntxuav, thiab thaum kawg muab tso rau hauv qhov chaw huv kom qhuav thiab ua kom tsis huv, yog li xyuas nws zoo ua ntej tawm ntawm lub Hoobkas.
