I've been working on and off for over a year trying to develop a green version of the Waterfall Brown glaze. It's a glaze developed by John Hesselberth and Ron Roy, and featured in their book - Mastering Cone 6 Glazes.
If you mix your own glazes and need help, or if you want to start doing so, I can't imagine a better book to get you started.
About my green tests, I've come up with so many versions of green, my studio is full of samples. I have a small piece of pegboard hanging right above my glaze mixing area, where all the samples are stored.
Since I'm mostly trying to develop a green for use in my hand made tiles, I'll tell you a little about the test tiles I make.
I made a small jig that allows me to cut a half dozen rectangular tiles at once. This allows me to roll out a slab and cut six tiles in seconds. I also use a small circular cookie cutter for making small circular tiles. Sometimes, I even make small "tubes" of tile, similar to the cardboard center on a roll of paper towels, only much smaller. I make them roughly the size of a finger, which allows me to test dips in the glaze sample. This is really helpful for learning if a glaze drips during it's final glaze fire. See, I figure if I'm going to the trouble of mixing a 100 gram batch of a glaze, I might as well dip it on a few tiles, rather than just one. So I generally test a glaze on 3 different bisqued clay.
I tend to not add a lot of texture tiles I make for furniture, but still, I want to see how the glaze behaves over texture. So I'll occasionally stamp something in the clay, just to experiment a bit.
The tiles above show a green that's way too light, but the crystal pattern is strong and well formed, which is, besides the color, something I'm trying to achieve.
In the next two tests, I tweaked the colorants slightly, and while there are still some great patterns within these tiles, the color is off. It's much too light for what I'm hoping to achieve.
I'm getting closer to what I want with these two, but I still have to play with the colorants. I envision a hunter green glaze, and these are still a bit too bright. They're very nice, if you like teal versions.
Switching to copper carbonate made the tiles much more pleasing, and put me on a better path for getting the color I want.
It's a simple test, but it takes 3 days.