I use Steven Hill's Water Color Green as an accent ( it is runny). Works well in the middle of a bowl or tray. Here it is on the side of a toasting cup.
Check out Steven's pottery....many have the water color green accent.
Water Color Green ( cone 6 oxidation)
Custer Feldspar 45.5
Flint (silica) 16.1
Lithium Carb. 3.8
Frit 3124 4.7
Strontium Carb 7.1
Copper Carb 7.0