Prior to the coating the surface that is being coated requires some pretreatment.knowing the amount and source of impurities help the elimination of them  .which contains oil and grease cused by machines trasportant or even workers skin.
According to the standard a complete pretreatment includes following steps:
-primary degreation
-secondory degreation
-rinsing with hot  water
-rinsing with cold water
-activation
-phosphating
-secondory rinsing with hot water
-secondory rinsing with cold water
-passivation
-rinsing with cold water
-rinsing with deionized water
The number of the steps that are required for the pretreatment depends on the type of impurities the use of item and also the required stability in salt spray test.at least four of the above steps are required.