I use Duncan EZ strokes for my green decorations. Copper can definitely
be problematic in slip and, for me, doesn't get that green.
I use Hacienda Jade (looks turquoise before firing but fires a nice deep
green), Grass Green, and Ivy Green. All stay green, without taking on
the brown tones of chrome, up to ^10 and are similar greens. I also use
Irish Green as an accent color.
