We have a potential customer presently coating stainless steel with a three-coat finish system, epoxy zinc/epoxy/urethane. I am wondering about the validity of using an epoxy zinc over stainless steel. Is there a possibility of a compatibility issue? Is this a common practice? The items being painted are valves and could have both carbon and stainless steel components. P.L.
At first glance, I wouldn’t worry about compatibility as much as overkill with the three-coat finish system you described. It is not a common practice to apply a zinc/epoxy primer over stainless steel.
On the other hand, if the products, valves in this case, could have both stainless steel and carbon steel components and will be subjected to extremely corrosive exposure conditions, the epoxy zinc primer would provide corrosion protection to the carbon steel. You will have to sort out all the details with your potential customer, keeping in mind that the customer is always right. Perhaps, you can show him he will be paying for something he really doesn’t need. In which case, the customer will be happy and you will be a hero.