Quote Originally Posted by zLynk View Post
Brass doesn't react with copper, so it could be used for the top. There would be no need to plate it, except to appeal aesthetically. Brass tarnishes quite readily, so a top made out of the material would start turning brown in no time; that's the reason for a nickel plating.

Aluminum is cheaper and softer than brass. Tooling costs for cutting the material are cheaper, since the bits last longer. Anodizing is cheaper than plating.

It's all about the money, bud.
The problem is, the GTX is double plated. The smart thing to do was stay away from the aluminum but, seeing that's what they used, they should have stayed away from the zinc/cobalt plating and just tripled up on the nickel thickness. Zinc is an anode metal and even though it's mixed with cobalt, I suspect that's what's starting the whole corrosion process. All it would take is a bad blend (ie. heavier on zinc side) to get it started. I defended the stock GTX top for quite a while, that was until knowledgeable users started getting this problem.