Nickel plating - can anyone offer advice on why it won't stick ?

[mikepilk]

I decided to try something new - nickel plating on brass wristwatch cases.  First I tried it on a scrap case and got good results.

So I bought a cheapish Cyma wristwatch with a scratched case, and felt confident of getting good results - but the plating won't stick 

I removed the existing plating electrolytically with a stripping solution (sulphuric acid based). It did the job nicely but left a matt surface. 

So out with the Dremel and polishing pads until I got a lovely shiny case ready for plating. My first attempt confirmed what I'd read, that the finish you get is what you've prepared  - plating doesn't hide anything.

I ultrasonically cleaned the case, then finished in isopropanol to remove any residue. 

Before plating, I dipped the case in to a pickling solution, then rinsed in distilled water. 

I thought the plating would be easy after all the preparation - but nothing is sticking, just flaking off. 

I tried cleaning again in the ultrasonic with Elma WF Pro - which removed the bits of of nickel, then IPA, pickle, distilled water. 
But same results, the plating isn't sticking. 

I don't know what else I can do to prepare the case, I've been as meticulous as I can. 

Could it be that my plating solution is somehow contaminated ?

 

Edited August 12, 2021 by mikepilk
type

[oldhippy]

I found this for you.

 The most likely cause though is that there is a loss of electrical current or electrical contact during the plating process. This would lead to the nickel deposit becoming "passive" and any consequent nickel deposition would not be fully adherent.

[AndyHull]

You might have to copper plate the item before you nickel plate it.

[nickelsilver]

I am no expert but I do nickel plate brass a couple times a year. Procedure is essentially the same as yours, except I've never pickled the brass as part of the process. For something shaped like your case I'll make a 3 point holder so the electrcal contact is evenly spread, and I've found using copper is noticeably better than brass as a holder (but brass does work). If there's a heavy buildup of plating on the holder I'll sand it off or make a new one.

 

The solution I use uses about 2 volts. When you rinse after cleaning the water should come off in a sheet and not want to bead up. You can look up "water break test for plating" to learn more.

Plating can be a hair-pulling-out process, even professional platers run into problems sometimes that should be basic.

Edited August 13, 2021 by nickelsilver

[mikepilk]

I should have checked that the water doesn't bead before plating. I've since read that you should rinse well after pickling to remove all acid residue, I just dipped in distilled water, so maybe not clean enough. 

I like you idea of a 3 point holder - I just had a piece of copper wire through the stem hole, so maybe not great contact. I'll try with copper wire across the inside of the case. 

I run at 0.2 amps, which is about 2.5V

I'll also try heating the solution. I was doing it at room temp, rather than the recommended 30-50C.

Hassle is I've got to start from scratch, stripping the nickel and polishing again 
As it's a snap on back, I've got to be careful not to erode the thin ridge the back clips on to. I made that mistake on my first attempt - ruined the case of a Cyma cal 414 I'd just bought, by using the wrong acid in electrolytically removing the nickel plate. Arrgghh  , and it's so hard to find cases for vintage movements !  

 

[mikepilk]

I decided to do some tests to determine what sort of cleaning I need to do prior to plating.

I took a new strip of brass, hand polished it with Brasso, then cleaned (hand rubbed) with naphtha, isopropanol, distilled water.

The result when sprayed with distilled water :

Nowhere near good enough. Hmmm

EDIT :  then I discovered my atomiser spray wasn't clean enough !

When I run a stream of water over, it doesn't bead any more. 

I'll be trying this before plating, but not so easy to do on a watch case.

 

Edited August 14, 2021 by mikepilk

[JohnR725]

On 8/12/2021 at 7:40 AM, mikepilk said:

but nothing is sticking, just flaking off.

where did your  solution come from? In other words does it have a name something we can look up?

 

[mikepilk]

58 minutes ago, JohnR725 said:

where did your  solution come from? In other words does it have a name something we can look up?

 

I made it myself, clear vinegar and use nickel plates as both anode and cathode. Pass a current until you have a nice green solution.

I did add a bit of sodium laureth sulphate to act as a surfactant - it reduces the size of the bubbles on what you are plating, giving a better finish.

I'll try it on the above bit of brass to make sure there's nothing wrong with the solution.

It's all new to me, I'm learning as I go. As @nickelsilver says 'even professional platers run into problems sometimes'

It's interesting playing around with it - just got to be careful as the acids are quite strong.

[JohnR725]

1 hour ago, mikepilk said:

It's all new to me, I'm learning as I go. As @nickelsilver says 'even professional platers run into problems sometimes'

the reason I asked who made the solution was? Usually not always but a company making a product would tell you how to use it. in other words plating isn't always a simple as have a solution throw something in and have a plate perfectly.  

[canthus]

Just wondering if adding the surfactant (ie adding other elements) to the plating solution is having an unbalancing effect.  I believe the distance between the anode and cathode can also have an effect in how quick/thick/stable the plating coats are applied.

[mikepilk]

4 hours ago, canthus said:

Just wondering if adding the surfactant (ie adding other elements) to the plating solution is having an unbalancing effect.  I believe the distance between the anode and cathode can also have an effect in how quick/thick/stable the plating coats are applied.

I'll try the solution on the piece of brass strip to make sure it plates OK.

I'm not sure what the ideal distance is, I'll do some research. I just know that if it's too close you get less even coverage.