Garnet Color in Lead Glass.
Make a mixture of 20 pounds of crystal frit with 16 pounds of lead calx. Sift these materials together carefully. Put them in a crucible with 3 ounces of Piedmont manganese, and ½ ounce of zaffer, both prepared [chapters 12, 13].
At this point, mix all the material in the pot. See that you do not expose them to too much heat, as usual. Leave them alone in the pot for 12 hours, and then empty all this glass into water. Remove any metallic lead that condensed out in the glass, as well as any in the pot. Then reheat the glass, and leave it to clarify for 10 hours.
Stir it and verify that the colour is good. To that end, you may need to charge or uncharge it with colour as is appropriate for the work, using the observations for working Iead glass [in chapter 641. Then you will have the most beautiful glass of a very attractive garnet colour.