Activating old Nickel plating for Replating

A. Hi Sam. Plating is still largely an empirical science. What works works, and what doesn't work doesn't work ... there isn't an answer to your question based on first principles, there is only experience. Anodic cleaning is certainly more effective than cathodic cleaning, but my own limited experience says that the shop technician's approach is correct and yours is "iffy".

I would suggest plating some coupons with both approaches and trying adhesion tests such as strong tape, filing, and bending the coupons around a small mandrel. If the Wood's strike proves better in your coupon tests, then it's better, and I would resist arguing for "good enough"

If you can find it in a local library, Electrodeposition [on on Amazon or on AbeBooks affil links] describes incredibly strong adhesion results for Wood's Nickel on stainless steel, and I would suspect similar results are possible for nickel on nickel -- but be sure to read the postings on this thread by Jeffrey Holmes suggesting that an iodine process is better for nickel on nickel.
Luck & Regards,

Hi again, Sam. You may well be right. Activating nickel is probably somewhat different than activating stainless steel, and it's possible that other approaches are as good as Wood's nickel or better.

Luck & Regards,


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

A. Try light and uniform sandblasting on the surface, then ultrasonic rinse in acetone ⇦this on eBay or Amazon [affil links] Warning! highly Flammable! for a few seconds to loosen dust. Water rinse may also work.

A. Rajiv, I suggest you to use the following process 1. Soak cleaning 3 minutes to eliminate possible oil and dust dirties on the surface; 2. Tap water rinse 2 minutes; 3. 30% HCl immersion for 1 minute to remove oxide on the surface; 4. tap water rinse 2 minutes. If this process does not work well, use 15%BV sulfuric acid + 20 g/L iodide 80 °F 3 minutes to replace step 3, which is more efficient to remove nickel oxide. Your adhesion problem mainly results from surface contamination and oxide. Good luck! Ling

A. The best way to activate "old" nickel deposits is a cathodic cyanide activation: 60 g/l sodium cyanide plus 60 g/l sodium hydroxide. In case you can not use cyanide, activate cathodically with hydroxide alone. Another possibility is activating with a 5 % sulfuric acid, also cathodically.

A. I think you can use Sara's recipe but I would use 50 g/l sodium hydroxide and 40 g/l orthophosphite 10 g/l sodium cyanide activate cathodic 2-3 min. And second step activate in a sulfuric acid 60 % until it starting gas-formation. But you must rinse between. Third step activate in a nickel strike. Good luck
Regards

A. If the nickel has been work hardened, then it is very difficult to activate or even dissolve. First make sure the surface is clean of all oil, grease, or other soil. I would use a stronger solution (e.g. 50% by volume) of hydrochloric acid for at least 2 minutes. Do not rinse with methanol, acetone, or deionized water. These will re-oxidize the surface. Alternatively you could use a Wood's Nickel solution to first etch then nickel strike the "old Nickel" surface. Is your wetting problem too much wetting, with flashing going everywhere, or too little wetting? If the wetting is excessive, selective plate (brush plate)nickel on the area that will be soldered. If adhesion is also a problem try brush copper plating on top of the "old nickel." and then solder on the copper.

It will not work if the "passivation" (read oxidation) is extreme. However, mild passivation may be reactivated in one pound per gallon sodium or potassium cyanide, perfectly clean D.I.water, stainless steel anodes, work cathodic at about 6 to 8 volts, absolutely no other cyanide soluble metals present. If any copper, zinc, or other is present as contaminant, then it plates onto the passive nickel and does not bond.

A. It will work most of the time and is the best strike for your purpose. You will find that some old oxidized and some polished nickel will take a lot stronger activation step.

A. Hi, Stan.

Actually I don't think I would summarize the thread exactly the same way:

A Wood's nickel strike, using nickel anodes and direct current (the workpiece being cathodic or negatively charged) is a very widely accepted approach to activating nickel for plating upon it. Some users do apply reverse current for a period of time first.

But if the nickel is "old" or "not fresh", some readers suggested that the nickel strike should be proceeded by etching in acid with lead (or much more expensive DSA) cathodes. Mr. Patel said that the current for this should be "direct", but I think this may be a semantic error, and I agree with Mr. Sundman's posting that the workpiece should be anodic for this step. If possible, please review the "Adhesion" chapter in Jack Dini's "Electrodeposition: The Materials Science of Coatings and Substrates" as it offers quantitative data from testing some different approaches to Wood's Nickel activation (although it actually tests nickel on stainless steel rather than nickel on nickel)

Regards,

A. Hi Joshua. We appended your inquiry to a rather similar thread as food for thought. Whether electrolytic nickel on nickel or electroless nickel on nickel, Wood's nickel strike is the standard answer. If you can comment with specifics regarding anything you've tried, and what results you got, the dialog can probably continue most productively. Thanks.

The issue is well covered by the "Adhesion" chapter in Jack Dini's "Electrodeposition".

Luck and Regards,

A. Hi Joshua,
Follow below steps for activating nickel alloy for better adhesion in electroless nickel plating.

1. Etch with ferric chloride ⇦this on eBay or Amazon [affil links] 280 - 290 g/l + HCl 38 ml/l for 90 seconds operating temperature RT.
2. Rinse with DM water
3. Wood's nickel strike--> NiCl26H2O 350 g/l + HCl 22 m/l for 110 Sec at 3.5 amps/dm2
4. DM Water rinse
5. Electroless nickel plate

A. Hi Ben. Have you tried a Wood's Nickel Strike or a Sulfamate Nickel Strike before the 2nd layer of Sulfamate Nickel?

Regards,

A. The cyanide or citric acid activation must be with current; the part is cathodic and it's only good for moderately oxidized nickel. Ted's advice of Nickel Chloride Strike is required for old tenacious heavily oxidized nickel.

A. I suggest that you activate the first nickel electroform by immersing it in the nickel plating bath and then make the part anodic for 30 to 60 seconds and then make the part cathodic without removing it from the bath. As long as your nickel anodes are working properly, this activation process will work.

"The Canning Handbook of Surface Finishing Technology"

on AbeBooks

or eBay or

Amazon

(affil links)

A. The Iodine based formula for nickel over nickel activation contains potassium iodide, sulfuric acid and iodine. I have used it, and it works every bit as well as the Wood's nickel strike. Maybe even better.

If you can find a copy of The Canning Handbook it is in there.

Here is the iodine activation formula -

Add to one gallon of water the following chemicals:

3 Fluid ounces of concentrated sulfuric acid slowly with stirring.

One third ounce of Potassium Iodide.

0.002 Ounce = 0.062 Grams of solid Iodine.

The Potassium Iodide is dissolved in a separate small amount of water and the solid iodine is added. When the iodine has dissolved the solution is added to the cold diluted sulfuric acid solutions and thoroughly mixed. In use, the iodine should be added periodically to maintain a straw color.

A. Hi Tom. Removing the chrome is necessary, but easy; a quick dip in muriatic acid will do it. But that isn't the big issue confronting you :-)
We appended your inquiry to a thread about activation/re-activation of nickel plating so you can read about the importance of it and a few different approaches you can try towards accomplishing it.

However, as general advice to you & others, I don't think that trying to re-nickel plate an instrument's chrome plated buttons should be your very first attempt at plating. There is so much to proper plating, so many variables to manage, that I think you should get some clean, highly plateable, brass coupons (as typically used in a Hull Cell) and demonstrate to yourself that you have workable chemistry, operating conditions, and technique for very basic nickel plating before trying to get good plating on a substrate which challenges people with decades of experience. Good luck.

Regards,

A. I've never heard of any of these nickel reactivation systems before. What we usually do is either use an electrocleaner with the polarity reversed, or you can also use a sodium bisulfite and sodium fluoride solution that is an immersion process. No electricity. You can also use both in series (electrolytic activation, steel acid, and then immersion process).