Adding Powder to Existing Paint Line

Question:

I am a high production liquid spray painter who is interested in powder coating. I would like to add powder booths to my existing liquid production line, which consists of a five-stage washer, dry-off oven, two back-to-back water-wash spray booths and a bake oven. My questions are can you add a powder booth to a liquid paint line and will my air makeup screw-up the airflow in the powder booth and cause drifting? I plan on installing a manual spray-to-waste powder booth if this means anything. A.F.

Answer:

Yes, you can add a powder booth to your liquid system with some precautions. First, check your pretreatment system performance to verify you have a water-break-free surface on your parts. Second, you should verify that your parts are completely dry after the dry-off oven and are below 100F where you plan to install the powder booth. Third, you should verify that you have sufficient time and temperature in your cure oven to cure a powder coating (typically 15-20 min at 325-350F metal temperature).

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Only proceed with the project if the answers to all three of these questions are positive or if you can improve your system to achieve these goals. If you do proceed, then position your powder booth before your liquid booths to ensure that liquid coated parts do not drip into the powder booth. Be sure to duct your air makeup system away from the powder booth openings and size the outlets to reduce the air velocity to less than 50 fpm. This will eliminate any powder drifting problems. Selecting a spray-to-waste powder booth will ensure that solvent fumes from your liquid spray operation will not contribute to reclaim problems. Lastly, check your cure oven for a high velocity flash-off zone at its entrance. If this zone exists, then lower the velocity or turn it off to prevent blowing the powder from the part before it has a chance to cure.

If you follow this procedure, you will have little problem adding a powder coating booth to your liquid operation. In fact, it is done all the time. I hope that other liquid spray operations read this answer and follow your lead. They (and you for that matter) will enjoy the elimination of hazardous waste disposal, the reduction of air makeup, lower energy costs, lower coating material costs and reduced maintenance costs.

Revisiting a Question

I answered a question about using electrocoating and powder coating to eliminate rusting on the inside of railings made from pipe. My thought was to use the electrocoating to cover the inside of the pipe and provide a good primer for the outside that would be covered with powder. Well, I received two challenges to my answer that informed me that electrocoating would not have the “throw” power to coat the entire inside of the railing. One response stated that possibly dip coating (non electrocoating) would work. Thanks for the input.