Umphumo wokukhetha kunye nokugqithisa ngexesha lokucwangciswa kwangaphambili, ukuwelda, ukuvavanywa, kunye nokunyangwa kobushushu kuya kubangela ukuba i-iron oxide, i-welding slag, igrisi, kunye nolunye ukungcola luqokelele phezu kombhobho (umbhobho we-carbon steel, umbhobho we-carbon copper, umbhobho wensimbi engenasici) , eya kunciphisa ukunyanzeliswa kwe-corrosion yombhobho wensimbi. Iintlobo ngeentlobo. I-Pickling yindlela yokususa umhlwa yekhemikhali: dilute ukususwa kwe-asidi ye-asidi ikakhulu isusa iioksidi zesinyithi kumphezulu wemibhobho yentsimbi engena-oksijini. Kwizinyithi ezinentsimbi, ibhekisa ikakhulu kwi-iron oxide, esebenza ngokwekhemikhali kunye nezi oxide zetsimbi kwaye izinyibilikise kwiasidi ukufezekisa injongo yokususa umhlwa. Ngaphambi kokukhethwa kunye nokususwa kwe-rust, igrisi eludongeni lombhobho wensimbi engenasici kufuneka isuswe kuqala, kuba ubukho begrisi buthintela ulwelo olukhethiweyo ukuba ludibane nodonga lombhobho wensimbi. Ichaphazela isiphumo sokususa umhlwa. Imibhobho engenaoyile (enjengemibhobho yentsimbi engatyiwa ngeoksijini) kufuneka ithotywe igrisi kuqala. Ukuvunwa kubhekiselele ekusebenziseni izisombululo zokukha ezifana ne-asidi yesulfuric ukuhlamba umaleko weoksidi kunye nothuli kwindawo yokusebenza. I-Phosphating yindlela yonyango yokucoca umphezulu.