▁and ▁gave ▁the ▁assembly ▁some ▁cor ros ion ▁resistance . ▁ ▁Elect ro de pos ited ▁co pper ▁ad her es ▁quite ▁firm ly ▁to ▁the ▁st ain less ▁steel ▁so ▁that ▁it ▁does ▁not ▁det ach ▁during ▁ref ining . ▁The ▁vertical ▁edges ▁of ▁the ▁st ain less ▁steel ▁pl ates ▁are ▁covered ▁with ▁tight - f itting ▁polym er ▁edge ▁stri ps ▁to ▁prevent ▁co pper ▁depos iting ▁around ▁the ▁edge ▁of ▁the ▁c ath ode ▁plate ▁and ▁so ▁make ▁it ▁easier ▁to ▁strip ▁the ▁c ath ode ▁co pper ▁from ▁them . ▁The ▁bottom ▁of ▁the ▁c ath ode ▁pl ates ▁were ▁mask ed ▁with ▁a ▁thin ▁film ▁of ▁w ax , ▁again ▁to ▁prevent ▁the ▁co pper ▁depos iting ▁around ▁the ▁bottom ▁edge . ▁W ax ▁was ▁used ▁rather ▁than ▁an ▁edge ▁strip ▁to ▁avoid ▁having ▁a ▁led ge ▁that ▁would ▁collect ▁falling ▁an ode ▁sl imes ▁and ▁cont amin ate ▁the ▁c ath ode ▁co pper . ▁ ▁W ax ▁was ▁also ▁used ▁on ▁the ▁vertical ▁edges ▁to ▁prolong ▁the ▁life ▁of ▁the ▁vertical ▁edge ▁strip . ▁ ▁The ▁original ▁c ath ode ▁stri pping ▁machine ▁was ▁based ▁on ▁that ▁used ▁at ▁the ▁H ik osh ima ▁plant ▁of ▁the ▁M its ui ▁M ining ▁and ▁Sm el ting ▁Company ▁of ▁Japan . ▁However , ▁considerable ▁development ▁work ▁was ▁necessary ▁to ▁modify ▁the ▁design ▁to ▁handle ▁the ▁co pper ▁c ath odes , ▁which ▁were ▁heav ier ▁than ▁those ▁at ▁H ik osh ima , ▁and ▁to ▁process