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Electroless plating: autocatalytic plating vs. immersion plating

Q. How can we apply plating metals without using external current..... but using vinegar ⇦in bulk on eBay or Amazon [affil links] & magnesium sulphate solution for slow plating and Copper sulphate for fast plating?

Thank You!

Gina L. [last name deleted for privacy by Editor]
school - Los Baños, Laguna, Philippines
2003

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Hello, Gina. The term 'electroless plating' isn't actually quite correct (around here) because that phrase is actually reserved for 'autocatalytic plating', as opposed to the 'immersion plating' that you wish to do.

In autocatalytic plating, the plating solution is heavily loaded with metal and with powerful reducing agents that will reduce the dissolved metal to solid metal in the presence of a catalyst. An electroless nickel solution, for example has nickel and hypophosphite in it; when the hypophosphite touches steel or solid nickel, it reduces the nickel ions dissolved in the solution to solid nickel metal on the part.

Copper sulphate will "immersion plate" onto clean steel, no problem. Copper dissolved into a solution of vinegar and magnesium sulphate ought to very slowly immersion plate onto steel, but you have to get the copper into solution first, of course. So electroplate some scrap items as described in our FAQs until there is at least a faint blue color to the solution, then detach the battery and immerse a very small steel item into the solution to see if you can get an immersion copper deposit.

Yes, copper sulphate has far more copper dissolved in it, as indicated by its dark blue color, and will plate out onto steel much faster. Good luck!

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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How can you explain the reaction happened in plating a penny and iron nail in a vinegar & Magnesium sulphate solution?.... And also what reaction occurred in the plating of iron nail in Copper sulphate solution?... These two experiments were performed without using external current.

Gina L. [last name deleted for privacy by Editor]
student - Los Baños, Laguna, Philippines
2003

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Hi again,

Copper is a more "noble" metal than iron, that is, iron is a more "active" metal than copper. When there are copper ions in solution and there is an iron surface exposed to them, the copper will "steal" the electrons from the iron. The result of this is that iron goes from metallic form to positively charged ions, and copper goes from positively charged ions to metallic form.

Regards,

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

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1. What are the roles of vinegar and magnesium in plating nail in vinegar and magnesium sulphate solution?
2. what are the half reaction involved for the plating of iron (nail)?

Mary Jane T. [last name deleted for privacy by Editor]
student - Los Baños, Laguna, Philippines
2003

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Hi, Mary Jane. I guess you are Gina's lab partner.

1. vinegar is an acid and allows copper and iron to dissolve into the solution. If there were no acid, the copper and iron would precipitate out at the bottom of the jar as copper hydroxide and iron hydroxide. The magnesium sulphate doesn't do much, just makes the water saltier and more conductive with Mg++ and SO4-- ions, perhaps allowing electrical charges to flow through the solution quicker and thereby for the immersion plating reaction to proceed a bit faster.

2. The half reaction is Fe⁰ + Cu⁺⁺ = Fe⁺⁺ + Cu⁰

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 12, 2011

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dear sir

We want to coat copper on coins, nails by electroless method. We need the correct procedure for it. Can you help us?

Kumar Sasi
researcher - Chennai
August 10, 2011

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August 10, 2011

Hi, Kumar. You took the time to at least read this one page, and you are quite sure that you want to do autocatalytic plating rather than immersion plating?

Regards,

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