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Old 10-07-2019, 11:20 AM
Desert Rat Desert Rat is offline
Join Date: Aug 2018
Location: 50-50 Wichita KS & Scottsdale AZ
Posts: 101
Default Zinc Chromate vs Zinc Phosphate?

For rattle can, do you guys prefer chromate or phosphate? Phosphate wasn't a thing when I went through A&P school approximately 1,000 years ago.
Terry Shortt
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Old 10-07-2019, 03:01 PM
tgmillso tgmillso is offline
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 728

The short answer is if you want the ultimate corrosion protection and don't care about a dose of hexavalent chromium and the subsequent cancer it causes, then zinc chromate is your weapon of choice. If you do care, then zinc phosphate is the next best option rattle can wise. If you dig through the archives there's plenty discussing both and some recommendations on quality zinc phosphate options.

Zinc phosphate (Wattyl/Valspar Superetch) and EkoPoxy
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Old 10-07-2019, 08:02 PM
Charles in SC Charles in SC is offline
Join Date: Aug 2006
Posts: 670

I am not sure about the chance of cancer is but I have used both. My take is the phosphate covers a little better but when you study some of the past success with chromate it is pretty impressive. I like using chromate but I try to stand upwind to prevent cancer.
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Old 10-07-2019, 10:26 PM
scsmith scsmith is offline
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,184

And it is not like the hexavalent chromium suddenly vanishes after you use it either -- it spreads out into the environment at large, and propogates a trail of death.

In terms of really toxic, nasty things to put into the environment, I would rank:

1) Plutonium

2) Dioxin

3) Hexavalent Chromium

4) DDT

....lots of other stuff.

This is why I've avoided using Alodine also.
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Last edited by scsmith : 10-07-2019 at 10:29 PM.
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Old 10-08-2019, 02:58 AM
mike newall's Avatar
mike newall mike newall is offline
Join Date: Jan 2005
Location: Yorkshire, England
Posts: 1,789

Avoid chromate at all costs, it is just not necessary. As a heavy metal, it builds within your system and is not excreted.

The protection from non chromated rattle can and spray primers with correct prep and de greasing is just fine. The base alclad is good enough - our priming just belts and braces it and gives peace of mind.

More protection is provided with ACF50 or Corrosion X after completion and painting.
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