What would I add to the teal coloring to get a good deep teal color?
Lots of Teal! Remember that the color will deepen as it sits, so if you can mix the color the night before you need it or at least a few hours, you'll know where it's going to go. Good luck!
Start light and go from there. The teal butterflies cake (in my pix) was done using ONE drop of teal in a very small amount of gelatin solution and it got darker. The general rule of thumb is to stop two shades lighter than where you want your actual color. Hope that helps some!