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Burnishing & corrosion-proofing zinc diecastings in one step

February 27, 2012

Q. I am wondering if there is such a sealer that can be used DURING the vibratory burnishing step. Currently, we are a captive die caster and for functional (non-decorative) die castings, we vibratory burnish and then we apply a rather traditional yellow chromate for some moderate corrosion protection. The chromate is primarily there to prevent white rust before our final customer installs the product (after which the corrosion protection isn't necessary.

We would like to delete the chromate step, especially the old barrel line we use to apply it. So if we determine that we cannot delete the sealer entirely, is there a way to apply corrosion protection in the barrel burnishing?

Jim Sweney
- Indianapolis, Indiana, USA

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Q. I am trying to come up with a formulation for copper burnishing. So far I have 12% citric 5% glycolic acid 5% soap 5% corrosion inhibitor. Running this at a 1 to 120 for 5 min the copper is still not as bright as it should be. I was thinking of adding some phosphoric acid. Any ideas would be helpful. Thanks Chip

Chip Sayre
- Staunton, Virginia, USA
April 24, 2012