Last Updated: Sep 26, 2016 Views: 84
According to Michael Bray at Dale Chihuly's hotshop, the three companies that the Studio buys color rods from are Kugler (Friederich Farbglashutte GmbH), Zimmermann and Reichenbach. The colors and chemistry are slightly different for each company and there are advantages to each. That is why the Studio doesn't buy color from just one source.
Zimmerman is no longer in business and they ceased making new color rod; however, there is still a lot of stock out in the world. See: http://www.glasscolor.com/colors/zimmerman_statement.aspx
Chihuly's studio will get back to me regarding their batch material. I will contact you when I hear from them.