Lists of Color Additives for Batch
The picture attached was a handout used at Penland. You will probably need to download it and expand it a bit in whatever you look at photos in to read it. I had to shrink it big time to get it to fit here. I always thought it was Dudley's but he says it isn't.
The list below is from Penland too.
With any formulas like this it's best to just extract the coloring oxide percentages and try those in whatever batch you're working with. That's best done with the old trick phrase for percentages, target over total times 100. Target would be the coloring oxide you're working with divided by the total of all the batch ingredients. Then multiply what you get by 100 (or just move the decimal point two places).
Keep in mind which glasses want oxygen to show color and which don't.
Manganese wants oxygen to show purple - add a pinch of potassium bichromate to ensure it has enough - 3-5% potassium in the batch will radically improve the purple color. It's brownish without it.
many silver and all copper ruby glasses want reduction - best accomplished with black tin
phosphates have so much oxygen in them you can forget reducing colors in them.
Most of the coloring chemicals can be had from US pigments:
Penland Additive Formulas for 19 pounds of batch. (I think this may be wrong, seems like an awful lot of colorant for 20# of batch on some of these)
· Purple: 200g mang dioxide, 90g soda ash.
· Opal Purple: 70g mang dioxide, 15g cobalt carb, 450g bone ash, 95g soda ash.
· Violet: 150g mang dioxide, 5 10g cobalt carb, 65g soda ash.
· Opal Yellow: 110g cadmium sulfide, 20g sulfer, 650g zinc oxide, 70g. pot ash, 90g
· Yellow: 128g cadmium sulfide, 660g zinc oxide, 68g pot ash, 95g soda ash.
· Yellow Orange (for 18lbs): 40g selenium, 650g zinc oxide, 110g cadmium sulfide,
140g pot ash.
· Opal Green: 50g potassium dichromate, 20g black copper oxide, 450g bone ash,
85g soda ash.
· Opal Green 2: 25g potassium dichromate, 10g black copper oxide, 90g borax.
· Opal Jade: 40g black copper oxide, 20g potassium dichromate, 450gbone ash, 95g
· Turquoise: 200g copper carb, 55g potassium dichromate, 95g soda ash.
· Blue: 200g copper carb, 7g cobalt carb, 25g potassium dichromate, 90g soda ash.
· Med Dark Blue: 150g black copper oxide, 90g soda ash.
· Opal Dark Copper Blue: 240g black copper oxide, 405g bone ash, 90g soda ash.
· Lapis: 50g cobalt carb, 180g borax.
· Opal Lapis: 30g cobalt carb, 10g black copper carb, 450 bone ash, 85g soda ash.
· Opal Red: 128g cadmium sulfide, 64g powdered selenium, 600g zinc oxide, 68g pot
ash. 430g bone ash, 430g bone ash, 95g soda ash. To darken, add 72g selenium,
90g pot ash.
· Pink (18lbs): 40g selenium, 90g cadmium sulfide, 600g zinc oxide, 68g pot ash, 80g
· Black: 231 mang dioxide, 11g potassium dichromate, 32g cobalt carb, 118g black
Art is not a thing...it's a way.
Last edited by Dave Bross; 12-21-2016 at 02:26 PM.