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letter 41952

Dacromet coating questions

Dip-spin Coating Services pointer 

(2006)

Q. I have been receiving of late a lot of enquiries regarding Dacromet coating on fasteners, Please let me know how is Dacromet coating done and what is the significance of salt spray resistance in respect to hours.

Kapil aggarwal
- New Delhi, INDIA


(2006)

A. Dacromet is a trademark of Metal Coatings International, and it describes a zinc-rich dip-spin coating. It is a way of applying a sacrificial coating of zinc. My understanding is that it offers greater corrosion resistance than zinc electroplating (probably because it's thicker).

Salt spray testing is not a meaningful way to predict the life of zinc-based coatings though. The protection they afford in the real world comes from the formation of stable and insoluble zinc carbonate corrosion products that develop over time with exposure to the carbon dioxide in the open air.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2006)

A. Dacromet coatings (include Geomet coatings) is known by many professional people in China. Also it will develop rapidly in the field of metal anti-corrosion.

Willam [last name deleted for privacy by Editor]
- Guangzhou, China


October 12, 2009

Dear Sir,

Recently I saw a term "zinc flake coating". Is it the same as Dacromet coating?

Thanks.

Bryan

Bryan [last name deleted for privacy by Editor]
- Munich, Germany


October 12, 2009

Hi, Bryan. Probably. Dacromet is one brand name of what people might call "zinc flake coating". But please remember that you must never specify a coating that loosely nor quote to do a coating that is so loosely defined. A colloquialism like this might be used in a technical article, in context, where the meaning will not be misconstrued, but specifications must be carefully detailed. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


August 16, 2011

Q. What are the contents of Dacromet coating layer?
And what is plus overcoat?

Ani Wadghule
tech student - Maharashtra, India

August 18, 2011

A. Hi, Ani.

Dacromet is a proprietary product containing zinc flakes, aluminum powder, metal oxides, and binders. Metal Coating International will tell you that much, and maybe a little more of what you want to know, but not everything about it, because it will be trade secret. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 16, 2012

Q. My company has produced some parts with good appearance, but we need surface like stainless steel after Dacromet. Is it possible?

Masoud Nosraty
- Mashad, Iran



December 19, 2016

Q. I hear Dacromet will no longer be available after 2016. Is this true, and what is the acceptable replacement?

Betsy Simmons
fastener distribution - Rochester, New York USA


December 2016

A. Hi Betsy. I think you need to contact NOF Metal Coatings (formerly Metal Coatings International) for the straight scoop rather than relying on rumor, but my guess is that perhaps they have decided to move exclusively to their Geomet line which is, per my understanding, very similar but chromium-free.

There are several other suppliers of zinc-rich dip-spin coatings, including The Magni Group, Doerken, Sermagard, and Zintek -- but whether they are an "acceptable replacement" will depend on what the spec says. Good luck.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


Poor Dacromet Adhesion

August 20, 2017

Q. Hello,
I had a project about anti-corrosion coating for metal base parts in 2015 and got trouble with surface adhesion. Would you tell me what's going wrong? In addition I blast my parts and baked well according to standards.

mack clarity
- hamburg/germany


August 2017

A. Hi Mack. There are a lot of things that could have gone wrong, from operational errors to unreasonable expectations. As a starting point can you please quantify what you mean by "got trouble with surface adhesion" and what the base metal was?

If you phone a doctor and tell her you have a fever, it might mean infection, but that single symptom doesn't say enough; similarly, although poor adhesion often means insufficient cleaning, that's not always the case. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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