▁t ape ▁works ▁by ▁changing ▁color ▁after ▁expos ure ▁to ▁temper atures ▁commonly ▁used ▁in ▁ster il ization ▁processes , ▁typically ▁ 1 2 1 ° C ▁in ▁a ▁steam ▁aut oc lave . ▁ ▁Small ▁stri ps ▁of ▁the ▁t ape ▁are ▁applied ▁to ▁the ▁items ▁before ▁they ▁are ▁placed ▁into ▁the ▁aut oc lave . ▁The ▁t ape ▁is ▁similar ▁to ▁mask ing ▁t ape ▁but ▁slightly ▁more ▁ad hes ive , ▁to ▁allow ▁it ▁to ▁ad here ▁under ▁the ▁hot , ▁mo ist ▁conditions ▁of ▁the ▁aut oc lave . ▁One ▁such ▁t ape ▁has ▁diagonal ▁mark ings ▁containing ▁an ▁in k ▁which ▁changes ▁colour ▁( us ually ▁be ige ▁to ▁black ) ▁upon ▁he ating . ▁▁ ▁It ▁is ▁important ▁to ▁note ▁that ▁the ▁presence ▁of ▁aut oc lave ▁t ape ▁that ▁has ▁changed ▁color ▁on ▁an ▁item ▁does ▁not ▁ensure ▁that ▁the ▁product ▁is ▁ster ile , ▁as ▁the ▁t ape ▁will ▁change ▁color ▁upon ▁expos ure ▁only . ▁For ▁steam ▁ster il ization ▁to ▁occur , ▁the ▁entire ▁item ▁must ▁completely ▁reach ▁and ▁maintain ▁ 1 2 1 ° C ▁for ▁ 1 5 – 2 0 ▁minutes ▁with ▁proper ▁steam ▁expos ure ▁to ▁ensure ▁ster il ization . ▁ ▁The ▁color - ch anging ▁indicator ▁of ▁t ape ▁is ▁usually ▁lead ▁carbon ate ▁based , ▁which ▁decom poses ▁to ▁lead ( II ) ▁ox ide . ▁To ▁protect ▁users ▁from ▁lead ▁-- ▁and ▁because ▁this ▁decomposition ▁can ▁occur ▁at ▁many ▁moder ate ▁temper atures ▁-- ▁manufact