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  1. josefel

    Brown spots on powder coated brass substrate

    Here is a photohttp://files.engineering.com/getfile.aspx?folder=fe2b1594-762c-48bc-b47f-e3c9078832e6&file=brown_spots_on_brass.jpg
  2. josefel

    Brown spots on powder coated brass substrate

    They are brass doorknobs. The pretreatment is either vapor degreasing or ultra-sonic cleaning.
  3. josefel

    Brown spots on powder coated brass substrate

    We are having an issue where polyester powder coated brass samples are developing brown spots (almost certainly corrosion) after being powder coated and sitting for a while. The technicians claim they do not see this phenomenon during salt spray and humidity testing. Pinholes? Contamination? I...
  4. josefel

    micro cracks in polymer coating

    Compositepro, we are not synthesizing the polyester. It is a prepared powder coat from a reputable vendor. We are applying the polyester clear coat onto a metal substrate, curing it and then subjecting it to salt/fog testing. Then after ~24 hrs at rest at RT, the micro-cracking/crazing is...
  5. josefel

    micro cracks in polymer coating

    compositepro, wouldn't the polyester resin have to be under-cured to hydrolyze? If it were fully cured would it still be able to react with the water?
  6. josefel

    micro cracks in polymer coating

    Thanks for the responses. They were very helpful.
  7. josefel

    micro cracks in polymer coating

    The polymer is a spray on powder coat polyester. It is fine when it comes out of the salt/fog chamber, but after aging for ~24 hours at RT, micro cracks/crazing is observed. According to the Datapaq cure cycle profile it is being cured properly. Thoughts? Thanks.
  8. josefel

    micro cracks in polymer coating

    My first day on the job is today. I will find out for myself and then pass it along. I am unsure of the polymer, but the ambient conditions are just regular RT temperature and humidity as far as I know. Thanks for your response, cloa.
  9. josefel

    micro cracks in polymer coating

    Hello, we use a polymer coating on steel and although it comes out of the salt/fog chamber fine, after about 24 hours it shows micro cracks. Any ideas? Thanks in advance.

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