Q. Are there any specific gun settings or other issues for powder coating with silver metallic? Q.C.
A. Metallic powder coatings are typically denser than other powder materials. This can make it harder to fluidize and deliver the metal flake materials. In order to make it easier to fluidize, you should be sure that the air supply is properly dry.
PCI recommends that the air be a +38°F (+3.3°C) dew point or lower. Also, use a feed hopper, not a box feed system. A box system may work, but it is more challenging to control the distribution of the powder by particle size and pigmentation. In some cases, it can be helpful to have additional inlets into the plenum to add more air volume. Additional pressure alone may not provide good fluidization, where additional air volume (CFM) without additional pressure (PSI) can be helpful.
The spray gun should have a current limiter so that you can control the current draw. High current draw or rapid changes in current draw may cause differences in appearance as the gun-to-target distance varies. Limit the current to an optimum level, probably below 25 micro-amps. The electrode may get slightly heated and collect powder. It should be cooled and/or cleaned periodically. Use a reasonable flow rate and keep the gun back as far as practical. And make sure that you always have a very good earth ground.
Metal fabricators that laser-cut with oxygen take steps to prepare parts better for powder coating.
This alternative to TGIC-based polyester powder coatings offers similar performance and enhanced transfer efficiencies.
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