122 - Balas Color
Put crystal frit into a large crucible, [melt it] and throw it into water three times. Then tint it with prepared Piedmont manganese, so that it will become a nice clear purple, and add finely sifted potash. Put in enough of it so the glass becomes purple. Do this eight times, and know that the potash makes the glass turn yellowish, and somewhat reddish, but does not darken it, and always makes use of the manganese. The last time that you add the manganese, do not add any potash unless you coloured it too much, and so you will have the most beautiful Balas colour.