Wood's Nickel variations for plating on steel

A. Different companies have reasons why they prefer one formula over others. Speed of deposition is actually controlled more by the HCl concentration than the nickel. The higher the percentage of HCl, the slower it plates. They all plate painfully slow, but you only plate to a showing of color. Since you mention bandage, you are talking about brush plating. I do not think that they use Woods nickel for a nickel strike. In the long run, it is cheaper to use the chemicals from a significant vendor than to reinvent the wheel yourself. The will probably give you a copy of their plating procedures if you ask nice. They would like to sell you things like anodes and covers also.

A. A Wood's nickel strike is commonly used for stainless steel and other alloys which self-passivate upon rinsing after acid activation. It would certainly be helpful for steels having a tendency to flash rust, and a Ni layer will add to the corrosion resistance of your hardware.

Your 3rd Wood's nickel formula is commonly used, with the (8 to) 12 vol% HCl based upon the use of 36 wt% HCl (specific gravity 1.18). With a less concentrated HCl source, adjust the volume accordingly. E.g,, 10-14 vol.% for HCl (30 wt%). Use at ambient (indoor) temperature.

Note: These concentrations are suitable for stainless steel; a lower HCl level might work for steel. Avoid assumptions, keep records. and learn from your results.

Read the excellent Wikipedia on Hydrochloric acid ⇨
and note concentrations and the high vapor pressure. Hence, it is highly advisable to cover the tank with a plastic lid when not in use -- first remove the cathode bar (copper) & the anodes (with rinsing). It is also advisable (and perhaps legally required) to use secondary containment, so your tank should be within a larger tank or cut-off plastic drum.

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Titanium baskets ⇨
containing nickel pellets ($$$) are used as anodes in mass production. For your application, an inert graphite anode is more appropriate. Graphite pieces can be bought on eBay. Graphite is quite brittle, so use care in drilling through-holes for clamping (to a copper anode bar) or blind holes for threading. Or simply, purchase graphite electrodes (with or w/o threaded holes) from a 'Chemicals & Perishables' supplier at the link below.

For plating, 30 Amps/ sq. ft for 6 minutes is ample. A brief initial period with the power off, or with the current reversed (workpiece anodic) for stainless, is normally used for cleaning/surface activation. Do only as necessary for good adhesion; it causes undesirable iron build-up in the bath.

Platers like annealed copper wire (soft, conductive) for hanging parts. Copper dissolves in acids, so you may wish to pre-plate some lengths of wire: Lift the cathode bar, attach the wires, turn the power on and put the cathode back upon the tank (go in 'hot'). Re-use the wires as practical.

A. Sorry, Mark, but alloy plating like that won't work, and this is why ...

If you look at the electrochemical series you will see that copper is far, far, more noble than zinc (well over a volt difference -- enough to power children's "lemon batteries" and "potato clocks"). So your deposit will contain essentially no zinc even if you have 1000x as much zinc in your anodes and solutions as copper. Alloys can only be deposited when you have a complexor/chelator that very effectively ties up the noble metal (cyanide is most often used for brass plating).

Hopefully you know that cyanide is very dangerous, creates a gas chamber if accidentally acidified, and is utterly inappropriate for home or non-professional use.

Good luck with the Wood's Nickel.

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

A. Mark - send it to an electroplater.