Powder Coating Q&A: Wasted Powder

Q. Our material cost has been going up, though we have shopped and found lower cost powder materials. We measure usage, and it seems we are using more powder to coat our parts than we did a year ago. Our film build seems to be around the same, but we are wasting a lot more powder. We have checked our earth ground, and it is fine. We have tried a few different gun settings, but have not made much improvement. How can our powder use and cost go up while our purchase cost is going down?

A. The cost per pound is not the critical factor in judging a powder. Applied cost per square foot is what really matters. A few things could be a factor in your recent increase in material cost. First, check out your equipment. Is it in good working condition? Are you charging correctly? Clean the spray guns, check all the wear parts, check voltage and make sure the guns are working correctly. Check your gun set-up. Have the positions been changed? Is the voltage and micro-amperage still where it used to be? If you do not know where it used to be, you have some work to do on standard operating procedure. Has the line speed been raised? A faster line may reduce transfer efficiency. Finally, check out your cheaper powder. If the specific gravity (SG) is higher than your old powder, that could easily be your problem. A higher SG could indicate more filler and less resin. That means your new, cheaper powder is actually more expensive because it will not cover as much area as the old powder.

Originally published in the December 2015 issue.