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Which black finish is better for rust resistance?

2005

Hello,

I am a mechanical engineer. We have some parts usually be painted as black (prime first and then paint). It cost a lot works. Now we try to dip them. But I don't know the differences between Zinc plating (Black), Black Oxide and paint. Does anyone could tell me the SSH of those? And the advantages and disadvantages between them? Which method is the best for rusting resistance?

Any information are highly appreciated.

Best Regards,

Carrie
- Canada

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2005

Carrie.

It is important to know what sort of service conditions the product will face before choosing a finish , or changing an existing finishing practice.

- Paint . depending on type can last from 200 to 1000 Hours in a neutral salt spray test.

- Black Oxide. This can go for anything from 45 to 250 hours without/with a topcoat in a salt spray test.

- Black Plating. If its zinc with a trivalent chromate and topcoat this can go as far as 300 to 400 hours in a salt spray test.

Costs depend on the type of coating material chosen, thickness and method of application.

If you were to come back and say " I need a Black finish that will last so and so hours in a salt spray test, will have x hardness. or withstand y mechanical handling, someone might give you an accurate recco.

Regards

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

A. Hello Carrie,

E-Coat is a single coat primer that can double up a ready painted finish, and isn't as expensive as other paint processes. Any other metallic coat will be much costlier.
The good news is that it is popularly available as black. Look below your car seat and look at the sliders, they are probably E-Coat.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2005