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Small blisters on a new product only on the edge after annealing a nickel plated product [The Netherlands] 

November 13, 2006

I have a interesting question for you all after reading lots of articles on finishing.com,

We are a company which is plating for 50 years as a s small part of our total process. We use electolytical nickel plating.

For a new product we have a blistering problem. But only on te edges.

As pre treatment we use:

1. Hot degreaser (1 hour)
2. Rinsing
3. Sulphuric acid etching (5 min)
4. Rinsing
5. Hot degreaser (15 min)
6. Rinsing
7. Degreaser (20 min)
8. Rinsing
9. Electrolytical slphuric acid etching (35%) 45 seconds
10. Rinsing
11. Hydrochloric acid (4 min)
12. (it is possible tot use a nickelstrike)
13. Electrolytical nickel plating 16V 300 A/h 900 A

We renewed all rinsing baths, made a new Nickel bath to be sure that there are no metal contaminations inside. We tried anodical degrasing all without success. We lengtened our etching time. We think it is not a pre-treatment problem anymore.

It's a round part of steel which from the inside to the outside has a layer thickness of 5 - 8 - 15 and on the oudside like a coin 30 mu.

We tried starting with a low current to prevent burning the piece. We also had our product during 5 hours in a degreaser.

We tried a moisturizer to get a better spreading of the nickel layer. Not much effect. We use barrels.

It is probably a hydrogen entrapment but how is that possible and why only on the outside and what can we do to prevent this and what is cause.

Thanks in Advance.

Chris van Oene
Plating company - Amsterdam, The Netherlands

Come back and give more information. What kind of steel? Leaded? Nickel bearing? What kind of nickel plating solution, metal concentration, temperature, pH, what kind of anodes, etc This sounds easy, just get us some more information.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

Hi Chris van Oene,
All the efforts on ensuring good rinsing prior to plating is appreciated. This adresses a major issue. But then what after plating. How about the deposits after Nickel plating. What is the type of plating.
The problem clearly indicates that some acids or chemical substrates are left on the edges which are more prone to this defect after plating. Post rinsing and drying is also very critical.
Good Luck

Sanjeeva
Supply Chain - Bangalore, India