Chuck,

  Congratulations on your new powder coating venture.  Hopefully I can shed some light for you:

   The pretreatment of the steel should not be a major problem.  We can debate zinc phosphates versus iron phosphates versus non-phosphates but the correct answer depends mostly on 2 things:  how dirty is your part to start and are there any specific results you must meet, i.e. salt spray.  Your standard cleaner/coater iron phosphate solutions should clean and provide an adequate etch to the steel.  For a higher quality part, you may want to rinse with RO  (reverse osmosis) or DI (deionized) water.

  Your copper is where it may be a tad trickier.  Copper itself tends to have chemical resistance (to a degree) built into it and sometimes doesn’t really react with standard pretreatment chemicals.  The chemicals will degrease and clean the part, but may not etch it quite as well as they would steel.  Once again, it goes back to the exact results and longevity you are looking for.

    As with all of our students, my advise to EVERYONE is to have a GOOD chemical supplier.  They can save you thousands of dollars by recommending the correct chemical for your job.  They should be local and knowledgeable.  They will look at your raw parts, discuss with you the end results both you and the end user expect, examine your capabilities of cleaning the part from a machinery standpoint, and will come up with a solution that works best for you.

  If anyone is having trouble finding a top-notch chemical supplier in your area, shoot me a private e-mail to joey@powderx.com with your city and state and some basic information and I’ll be glad to see if someone in our network can serve you.

Joey