Metal finishing Q&As since 1989

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Electrostatic Spray of Thermoplastic Powders

I would like to know if anyone out there is using vinyl or thermoplastic powder to electrospray on to wire goods. We currently use polyester powder to coat wire products but have problems with edge coverage. I am wondering if thermoplastics would do a better job on edge coverage. Thanks Chris

Chris Ballew
- Newport, TN
2000

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Dear Chris:

Although thermoplastics do generally provide some advantage over thermoset powders, film thickness always plays a major role with coating sharp edges. Depending upon the products used, most thermosets will require 20-25 mils for total encapsulation while many thermoplastics may get the job done around 12-15 mils. This assumes the metal edges are NOT free of burrs. If the metal is de-burred, then these figures can be reduced by 25% or more.

For applications where thermoset products are desired, a dual coat process can be used successfully at films around 8-10 mils, provided the metal edges are free of burrs. The first coat is formulated for extremely low flow to cover the edges - however, it is generally not acceptable for appearance. The second coat is then applied for appearance requirements.

I hope this helps some.

Sincerely,

Matt Matheney
- Houston, Texas
2000