You don't want to be using fritts. Fritts are basically ground glass and are heavy.
You want to be adding clay to your mix for suspension.
I add Albany slip-one teaspoon to about a tablespoon of red Iron Oxide.
Not precise-just spoon in, mix up and brush.
Some potters use a mortar and pestle to get a fine grind, but I can't be bothered.
Also try a bit of black iron oxide to taste.
Check out my gallery for brush work.
The fifth image is unfired iron.