In this video you will learn about the reactive properties of some Bullseye glass. This is something I first came across while making simple cabochons from scrap, and again later when using fine silver as an inclusion. The silver reacted with some glass and resulted in a black discolouration.
In future work I intend to take advantage of this reaction to create some specific cabochons I have in mind.
While this reactive nature of some glass can be unexpected and annoying, I really think it is a property that can be used in your designs.