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-----sulfuric acid anodized luminaires turning yellow
2004
I work for a large electrical industry in India, One of our luminaire product [Halogen Flood Light] constructed from PDC Al. The internal Al fitment [99.7% pure] for the same is Sulfuric Anodized [Type II]. The sealing used is 5 - 10% nitric + boric acid dip. We are facing a problem of the internal Al fitting turning yellow on exposure to light [around 400 °C]. Any idea to overcome this problem of yellowing.
Regards,
Nilesh n. OturkarR&D Executive - Paint Technology - Mumbai, Mahrashtra, India
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The problem with the anodized coating turning yellow when exposed to light relates to the failure of the seal and the components of the seal that you are using.
David B. Hunt- Naperville, Illinois, US
2004
That strikes me as a strange sealing bath, Nilesh. Usually you would be using steam, boiling hot water, or a nickel acetate seal for that kind of application (in my experience).
Ted Mooney, P.E.
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