Tshwj tsis yog tsis muaj lwm yam, cov fiberglass tws strand cov khoom yuav tsum muab cia rau hauv qhov chaw qhuav, txias thiab noo noo thiab noo noo. Qhov zoo tshaj plaws siv nyob rau hauv 12 lub hlis tom qab hnub ntau lawm. Fiberglass tws strand yuav tsum nyob twj ywm hauv lawv lub ntim thawj kom txog thaum siv ua ntej siv. Cov fiberglass tws strand cov khoom lag luam yog tsim nyog rau kev xa los ntawm txoj kev ntawm nkoj, tsheb ciav hlau, lossis tsheb thauj khoom.