Powder Clinic: Pinholes Mentioned in July Issue

Q. Just read the article in most recent issue of PF about our problem and wanted to respond with what we found out.
#curing #masking


Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

Q. Just read the article in most recent issue of PF about our problem and wanted to respond with what we found out. We sent a sample panel to a powder manufacturer and they had their chemist look at it. Their response was that the micro pores did not go to the surface of the part and it was moisture in the powder in combination with the moisture in the oven air that was on the surface of the part too long before evaporating, causing imprints. We had our gas company test the moisture content of the supply gas. They said it was at the maximum level allowed. This then led us to verify the volume of exhaust gas being expelled by the fan. We did the drive calculations and found it was at the minimum recommended level. We increased the pulley ratios by 30 percent and the problem has almost disappeared. Thanks again for your help.

A. You make a couple of important points. Using your vendors to analyze a defect can be very helpful. They often have expertise and analytical equipment that can be used to evaluate problems. Also, looking at the depth of a defect helps to understand the source. For example, a pinhole that exists at the surface but does not penetrate to the substrate is most likely an airborne contaminant. Your process of detecting the source was great. I’m sure you're glad to have it resolved.


  • Masking for Surface Finishing

    Masking is employed in most any metal finishing operation where only a specifically defined area of the surface of a part must be exposed to a process. Conversely, masking may be employed on a surface where treatment is either not required or must be avoided. This article covers the many aspects of masking for metal finishing, including applications, methods and the various types of masking employed.

  • Understanding Infrared Curing

    Infrared cure is gaining increased attention from coaters as a result of shorter cure cycles and the possibility of smaller floor space requirements when compared to convection oven curing. 

  • The Powder Coating Process

    Powder coating is one of the most durable finishes that can be applied to industrial manufactured products, and offers excellent corrosion protection and is very safe because of its lack of volatile organic compounds.