Watts nickel analysis

A. I'm a little confused. Watts bath is not normally used as a strike. Instead, a low pH high chloride bath known as Woods strike is very common or alternatively a sulfamate acidic bath. Both are used to preplate difficult metals. Please explain more what type of substrates you normally strike with this bath and why are you concerned about sulphate conc.

A. John,

I'm asking right now myself how could you plate with an pH of 9-10? Wasn't it a really rough deposit which you get?
Anyway, here is a procedure to determine the Chloride and sulphate content as Nickel sulphate and Nickel chloride. Depending the amount of chloride and sulfuric acid in your tank you might should choose which (diluted) acid will be necessary:

Determination of Nickel metal:

2 ml electrolyte sample into 300 ml Erlenmeyer flask
dilute with 100 ml DI-Water
then add 10 ml ammonia ⇦ this on eBay or Amazon [affil links] 25% and 1-2 Spatulas murexide [affil links] Indicator (=>1 g Murexide mixed with 100 g NaCl)
Titrate with 0.1 M EDTA-Solution until color changes from golden yellow to violet.

Calculation:
Usage of EDTA-Solution in ml x 2.936 = content of Nickel metal in g/l.

Determination of Nickel chloride:
2 ml electrolyte sample into 300 ml Erlenmeyer flask
dilute with 100 ml DI-Water
Then add 3 ml 10% potassium chromate solution(=> 10 g potassium chromate dissolved in 100 ml DI-Water)
Titrate with 0.1N silver nitrate solution from yellow to an onion reddish brown color.

Calculation:
Usage of silver nitrate x 5.945 = content of Nickel chloride in g/l

Calculation of nickel sulphate:
content of Nickel metal in g/l = "A"
content of Nickel chloride in g/l x 0,247 = "B"

(A-B) x 4.786 = g/l Nickel sulphate (NiSO4 x 7H2O)
(A-B) x 4.477 = g/l Nickel sulphate (NiSO4 x 6H2O)

Depending which salt you are using you should choose the factor.

Best regards from the alps and cows

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Ed. note: Thanks so much, Dominik!

A. Like Guillermo, I too am totally confused. I have always believed a nickel strike is a chloride based system with hydrochloric acid (aka Woods Nickel). It operates at a low pH. I have never heard of a Watts strike that operates in the alkali range, although there is a sulphamate strike, but I have no experience of that. It sounds to me like the nickel strike is totally out of balance and needs remaking with nickel chloride (240 g/l) and hydrochloric acid (sg 1.11; 120 ml/l). Perhaps someone can enlighten me on the Watts strike system?

A. I'm a little confused, too. At a pH of 9-10, almost all of the nickel metal should precipitate out as hydroxide! I'd lower the pH with sulfuric, too.

To check chloride, titrate with a standard silver nitrate solution to the dichromate endpoint. To determine sulphate (although I truly don't think it would be a problem with a Watts bath) you can precipitate the sulphate with excess of barium chloride solution and determine it gravimetrically.

A. Do you have a lab or any lab equipment? Are you a chemist or a lab tech or any plating solution analysis experience?
Most chemical suppliers will be happy to give you a test procedure for the chemical that they sell you. If you are buying proprietary plating bath chemicals, that company will give you an analyses method sheet and an operations sheet for the optimum level for each. Many will even have a sales or tech services person show you how to do it.
I imagine that you could even download it from the internet. There are many many plating analyses books on the market, most using low tech methods. High tech methods equipment would cost over $100,000 for state of the art equipment.
If you use the low tech methods, you will save a huge amount of learning curve time and possibly avoid results that are "off" if you have a qualified person show you how to do it.

A. Standard analytical procedures are available in most good electroplating books. Try The Canning Handbook [on eBay, Amazon, AbeBooks affil links].

A. Nickel Bath Analysis
Determination of Nickel metal:
1-take 2 ml electrolyte sample into 250 ml conical flask
2-dilute with 100 ml DI-Water
3- add 10 ml ammonia 33% and 1-2 Spatulas Murexide Indicator (=1 g Murexide mixed with 100 g NaCl)
4-Titrate with 0.1 M EDTA-Solution until color changes from golden yellow to violet.
Calculation:
Usage of EDTA-Solution in ml x 2.936 = content of Nickel metal in g/l.

Determination of Nickel chloride:
1-take 2 ml electrolyte sample into 250 ml conical flask
2-dilute with 100 ml DI-Water
3- add 3 ml 10% potassium chromate solution(=10 g potassium chromate dissolved in 100 ml DI-Water)
4-Titrate with 0.1 N silver nitrate solution from yellow to an onion reddish brown color.

Calculation:
Usage of silver nitrate x 5.945 = content of Nickel chloride in g/l

Calculation of nickel sulphate:
content of Nickel metal in g/l = "A"
content of Nickel chloride in g/l x 0.247 = "B"
(A-B) x 4.786 = g/l Nickel sulphate (NiSO4 x 7H2O)
(A-B) x 4.477 = g/l Nickel sulphate (NiSO4 x 6H2O)
Depending which salt you are using you should choose the factor.
Determination of Boric Acid:
1-Take 1ml electrolyte sample into 250 ml conical flask
2-add it to 25 mls of "Indicator B".
3- titrate the aliquot against 0.1N NaOH

Calculation:
mls NaOH x 6.184 = Content of [H3BO3]g/l

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Ed. note: Thanks very much, Sherif!