I have a customer that wants a smooth finish with no "orange peel". I am using a gloss white over a zinc epoxy primer on 1/4" thick aluminum.  I am fighting this effect and would like to know what I can try to eliminate it. I know that too much powder will cause it but I seem to get it no matter what thickness I apply. Does temperature or cure time have an effect on this? What can I try.....

Also, someone told me that a zinc primer should not be used on aluminum because "aluminum is sacraficial to zinc" and a "chemical reaction occurs between the zinc in the primer and the aluminum". Any truth to that?

Sorry Newbie .....

  I answered another question you had but totally missed this one until today.  Let me see if I can help:

  Zinc rich primers are used for corrosion resistance.  They are typically used over steel products and not aluminum because aluminum does not posses the same poor corrosion resistance.  If you eliminate the primer, the coating thickness will decrease as should the orange peel.

   As far as a chemical reaction (or interaction), there's not one that occurs to the best of my knowledge.  Maybe someone out there is reading the boards that is much smarter than me can elaborate.