Metal finishing Q&As since 1989

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Problems powdercoating over gold passivate

We have been experiencing problems with powdercoating over mild steel that has been gold passivated for outdoor furniture. The powder coat has been bubbling up and generally looks pretty ugly. I understand that this isn't an unheard of process, can anyone enlighten me as to the problems involved? Problems may stem from the pre baking (or lack of) prior to powdercoating, the thickness of both the passivate and the powdercoat and also the temperature of the oven during powdercoating? Any feedback would be great!

Nigel Upchurch
Furniture designer - Auckland, New Zealand
2005

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2005

Nigel Please investigate and verify the following ..

1) The passivate is yellow chromate.Is there a water lacquer dip thereafter.
2) Is there an inorganic sealant after chromate


There will be a layer that causes peel off of the powder coat from the zinc chromated layer.

Can we assume the parts are not more than say 48 hours old after Chromating. ? This factor is important.

Hope this helps.

Regards

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016

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2005

Thanks Asif,

It is yellow chromate, They have only been rinsed down following the passivate and there has been no sealant applied after.
Powder coating would have taking place in under 48 hours after passivating.

Nigel Upchurch
- Auckland, New Zealand