Ngwa:

1.it bụ tumadi eji maka nhazi nke inorganic ihe, dị ka iko, ceramics, mica, silica, kaolin, talc, wdg na-eme ka SiC na organic okwu (dị ka plastik, roba, roba mmanụ, nrapado) ndakọrịta na waterproof. arụmọrụ, welie n'ibu Njirimara nke ngwaahịa.
2. nwere ike ichebe oghere oghere na iko ọgwụgwọ ihe nkiri (mkpuchi mgbochi anya anya, mkpuchi mgbochi mgbochi, ihe nkiri na-egosipụta).Enwere ike ichekwa akụkụ anya ma ọ bụ ngwa nkenke na ngwa nwere akpịrịkpa na okpokolo igwe.
3. nwere ike igbochi acid corrosion, ifriizi-thaw, weathering mbibi nke omenala relics (karịsịa maka n'èzí omenala relics).