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Gold Plating Metal

I have a query about gold plating metal, I live in Indonesia and produce jewelry, mainly metal. We are gold plating and sometimes the gold doesn't come out evenly or looks slightly greenish. What are the correct proportions to mix the gold, and how to know what amount of gold to use to get an even finish.

Thanks.

Roma Fairbrother
Otazu - Batu Belig, Bali, Indonesia
2001

Roma,

We have been gold plating for over 50 years and the fault you mention is usually related to passivity of the undercoat or bad current distribution (too much work in the gold tank). You could use an activator between nickel and gold or you may only need better rinsing or an alkaline dip. We ensure that our nickel dragout is always quite acid (pH 2-4) and we rinse twice then through an alkaline cleaner and counterflow rinse before the gold. Another trick is to use a high current strike as the work enters the gold solution for only 1-3 seconds as the gold solution itself (hot alkaline solutions) are good activators. If you are using an acid gold you may need an alkaline/cyanide strike before the acid gold.

Hope this helps.

Bob Lynch
plating company - Sydney, Australia
2001