Ingredients

Ingredient Amount
Barium Carbonate 5.10
Dolomite 5.10
Whiting 8.17
Gerstley Borate 5.10
Custer Feldspar 51.02
Flint 25.51
Add Amount
Copper Carbonate 2.04
Cobalt Carbonate 0.26
Tin Oxide 1.02
Zinc Oxide 2.55

Instructions

I took this recipe from Blaine's book.  I don't think I asked.  Sorry Blaine.

The test tile is B-Mix fired in reduction.
This is, of course, a copper red, which means that if it's not fired in reduction, it will not be red (or grape in this case). Reduce early for nice color.