E l l a p s e d t i m e Z i n c O x i d e Z n O F r e e f l o w i n g a i r 0 M o i s t u r e f r o m r a i n d e w H O F r e e f l o w i n g a i r 0 C O 4 8 h 6 m o n t h s 6 m o n t h s 2 y e a r s 0 4 8 h Z i n c H y d r o x i d e Z n O H 2 Z i n c C a r b o n a t e 2 7 n C O Z n O H 2 3 2 2 2 2 F u l l y d e v e l o p e d p a t i n a When should paint be applied Galv anized steel has three 3 stages of aging when o xides are present and painting can be executed at any stage providing that the proper surface prepar ation is applied Immediately after the galv anizing treatment When the galv anized steel is at 50 of its life span When the thickness of the galv anized sheet is 1mils At the frst sign of rust Galv anized steel goes through a process of o xidation or aging that is illustr ated with the help of what is called passiv ation cycle 28