Hāʻawi ke kaʻina hana pretreatment i kahi silane ʻona ʻole ʻona hou i hoʻopihapiha ʻia, ʻo ia ka hana hoʻomalu hoʻomalu kūlohelohe kiʻekiʻe i ka ʻoihana. ʻO ka mānoanoa o ka uhi o ka papa he 50 ~ 80 μm, he laumania ia, heʻuʻuku ke kūʻē ʻana o ke kolamu hāpai, a kūpaʻa ka hāpai ʻana.