Q. We have problems with getting an adherent gold deposit on stainless steel. We have tried different cycles of alkaline degreasing and electrocleaning with little or no success. What is the secret to preventing peeling? —S.G.
A. The secret to success is good activation of the stainless steel substrate before the gold-plating step. Alkaline degreasing and electrocleaning usually are not adequate. Electrocleaning can cause you more harm than good if you cleaned the parts anodically; anodic electrocleaning passivates the stainless steel.
The best cycle to use for your parts is:
- Degrease using an alkaline degreaser.
- Clean the part cathodically in an alkaline cleaner.
- Treat cathodically in a 250 mL hydrochloric acid/1 L water solution.
- Use a current density of 20 asf for 3 minutes.
- Strike in a Woods’ nickel bath for 2–3 minutes.
- Gold plate.
Good rinsing between each step is very important. Also keep in mind that if the nickel can cause dermatitis for a significant number of people, so in cases where the part will come into regular contact with skin (as with jewelry), a barrier layer on top of the nickel will be necessary.blog comments powered by Disqus