Summary for black finish rust resistance Discussion
black finish rust resistance depends on the service conditions and the performance target, according to Khozem Vahaanwala. Carrie asked how zinc plating (black), black oxide, and paint compare for salt spray resistance, cost, and rust protection, since her parts are currently primed and painted and she wants to switch to dipping. Khozem said the right choice depends on the product’s environment and noted that paint can last roughly 200 to 1000 hours in neutral salt spray, black oxide about 45 to 250 hours with or without a topcoat, and black zinc plating with trivalent chromate and topcoat about 300 to 400 hours. He also pointed out that cost varies with coating material, thickness, and application method. His practical advice was to define the required salt spray hours, hardness, and handling resistance first, then choose the finish that meets those needs.
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
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