Nickel plating problem

[Newlands]

I'm trying to nickel plate a few brass bits -all smallish, this is 10mm sq x 64 long. Some have come out ok, but others not so much. They were all treated the same way - polished to 1000g with wet and dry, then buffed up with Solvol Autosol, 10-15 minutes in the ultrasonic cleaner, then cleaned again with brake cleaner. The electrolyte is Nickel Acetate. Each time some of them have come out like the one below, with a sort of crackle finish. This one is the third attempt - 0.3 amps and around 3v, using abenchtop power supply set to current limit. I put the initial failures down to too much current (around 2 amps at 12v) but reducing the current seems to make no difference.
Any experts here know what I'm doing wrong?

 

[voipio]

Cleanliness is one of the most important things to get right in plating. I've not done a lot of plating over the years, being more of an occasional dabbler, but one thing I've found is that even the tiniest amount of grease or oily residue remaining on the part to be plated, will result in a noticeable degradation in plating quality. The water purity used for rinsing, and making up plating solutions, also needs to be very high. Plating current density, and pH will also affect the plating quality.

 

[Misterg]

Did you interrupt the process at all (taking the parts out, or turning the current off)?

Is it a commercial solution, or homebrew?

 

[Agroshield]

There are six faces to the part shown. When it is in the bath, is the crinkle the top, bottom, etc.? Where is it in relation to the nickel electrode?

See here:

https://nickelinstitute.org/media/lxxh1zwr/2023-nickelplatinghandbooka5_printablepdf.pdf

 

[Dozzer]

Cleanliness, Cleanliness & Cleanliness.
Brake cleaner will only remove the oils, but any other dirt or contaminate will stick, and can leave a residue behind.
when we were doing any nickel plating or anodizing, it would be from the Ridaline or methyl tric bath, DI water rinse, then plating, only giving them a blow of with air gun, but wouldn't let them dry as it could leave staining. not sure you can get either of those cleaners any more as it was 40+ years ago.

 

[Screwdriver]

I think Solvol leaves a very thin wax layer and I wonder if ultrasonic would remove it. IPA would be a better bet depending on what sort of brake cleaner you're using. Wouldn't harm to try IPA in case the brake cleaner isn't taking off the Solvol residue.

 

[Newlands]

In answer to your helpful responses:
The nickel acetate solution was home-brewed - 1 litre of white vinegar plus a teaspoon of salt, plus 3 hours of electrolysis with nickel electrodes.
The crinkle finish is all over, every face. I did turn it round a few times, and used a little artist brush to get the bubbles off every few minutes. Total time in the plating solution was around 45 minutes, and yes, I did lift it out a couple of times to check it (but didn't touch it or dry it off).
I did wonder about the solved autos residue but assumed that brake cleaner would sort that out - maybe I'm wrong.
One thing I have seen recommended by some, but ignored by others, is a 2 minuted dip in hydrochloric acid plus rinse in distilled water before plating. Another thing to try I guess if you guys think that's worthwhile (brick cleaner from Wickes looks like its hydrochloric acid according to the data sheet).

Incidentally, I followed the procedure set out by Clough42 in one of his Youtube videos - he's normally pretty fastidious on this sort of thing, and he got good results when he plated some steel components.

 

[Dozzer]

If i remember from the dim & distant (please if there is a chemist correct me) using DI = de-ionized water helps with cleaning, as the water wants to reach a state of equilibrium so will happy steal ions from anything that comes into contact with it, this creates an attraction to any small particles. and will carry then away with the water, was told its the reason its used in all sorts of cleaning when no residue is important.

 

[Ross365]

I too am not sure about Solvol in this. What cleaner are you using in the ultrasonic? Many of the ultrasonic agents are caustic and will react with brass. Definitely don't like the idea of Brick Acid and brass.

 

[Newlands]

Here's two other parts I did this afternoon - 0.25 amps, roughly 3 volts for about 30 minutes. Exactly the same preparation as above, and a much nicer result for no apparent reason. (They are both for the guitar I'm building - the knurled one is for the pickup selector switch, and the other one is a support post for the back of the headstock, and doubles up as the fixing for the logo-emblem thing, hence the clear soft plastic bumper thing stuck in the recess at the top. And the thing in the first post above is the main part of the roller nut to hold the strings in place for those interested in such things)

Edit - "I too am not sure about Solvol in this. What cleaner are you using in the ultrasonic? Many of the ultrasonic agents are caustic and will react with brass. Definitely don't like the idea of Brick Acid and brass." I'm glad you mentioned the brick acid - one of the reasons I didn't use it was because I thought it might react with the zinc phase in the brass. As for the cleaner, just hot water with a couple of drops of fairy liquid.

 

[Misterg]

I did turn it round a few times, and used a little artist brush to get the bubbles off every few minutes

I tentatively suggest that this might be your issue. I've never done nickel, but recall from somewhere that you mustn't interrupt or otherwise disturb the plating while in progress.

I'm also dubious about whether residue from the polishing compound is being removed effectively, but not sure it would give you that 'mud cracking' effect.

 

[Newlands]

but recall from somewhere that you mustn't interrupt or otherwise disturb the plating while in progress

Many of the YT videos I've watched seem to think it's important to not let bubbles stick to the surface, and one even used a magnetic stirrer. I don't want to disagree with you because this is the first time I've tried this, so I know absolutely nothing, but I'm struggling to see how lifting the thing out of the bath for maybe 5 seconds is going to cause a problem. One of my thoughts was that in my earlier attempts I was leaving things in the bath for too long, hence giving it a check now and then. But I can easily resist that temptation if that's what's needed!!
The DI water is a good call, and I can easily pop to Halfords to get some. I also have some IPA to use instead of (or after) brake cleaner.
One other thing that I've read (in the pdf that @Agroshield linked to, and seen on YT) is that the nickel electrodes can be shrouded in a cotton bag to stop nickel fines entering the solution, and maybe that is part of the problem.
As always, thanks for the responses - really helpful and greatly appreciated.

 

[Seadog]

I didn't use it was because I thought it might react with the zinc phase in the brass. As for the cleaner, just hot water with a coupl

It will, you'll end up with a copper-coloured piece

 

[Kram]

The colour wouldnt matter if being plated.
Hot citric for a few minutes might be a better choice, but that too, will turn brass pink if left.

Quite impressed, apart from the crinkle the parts do look good.
Can I ask, what did you use for nickle electrodes? I might have to try it one day...