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Flaky zinc plating

I WORK ON A ZINC PLATER AND SUPPLY ALL THE CHEMICALS AND TESTS FOR IT. OUR PROBLEM IS TRYING TO PLATE OVER NICKEL WITH ZINC. SOMETIMES WE GET A LOT OF FLAKING WHEN WE BEND THE WIRES. THE WIRES ARE COPPER CORE NICKEL ALLOY. WE USE A SULFURIC PICKLE AT 20% WITH A FLUORIDE ACTIVATOR. TESTS SHOW EVERYTHING TO BE IN SPEC AND CLEAN RINSES. OUR PLATING TANK IS WELL FILTERED AND CLEAN. WE DUMP CLEANERS EVERY TWO WEEKS. ON WIRES THAT ARE NOT NICKEL ALLOY, LOW CARBON STEEL WIRES, THERE'S NO FLAKING AT ALL. ANY IDEAS?

HOMER KEITH
plating shop - BURLINGTON, IOWA, USA
2004

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Nickel, like stainless steel, immediately forms a passive layer to which plating will not reliably adhere. You need to Wood's nickel strike this wire before you zinc plate it.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004

Some specifications need Dacrotization of hardware. There is confusion that it can be Zinc coated as per ISO 10683.
Please clarify whether both are same or different & why.

Thank you.

Swaminathan S
Head - Manufacture - Bangalore, Karnataka, India
August 11, 2010

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Hi, Swami. Dacrotize is a trade name for a zinc flake process. ISO 10683 is a specification for the application of zinc flake processes to fasteners.

So, not all zinc flake coatings are Dacrotizing, just as not all automobiles are Hondas.

I don't have a copy of ISO 10683, but I do suspect that Dacromet / Dacrotizing can be in compliance. But you cannot proceed without a copy of the specification and assuring yourself that you are fully in accord with all of its provisos, not just some of them. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 11, 2010