I use all sorts of glass, but sadly I can't normally raid the local bottle bank for it!
When I first started, I worked with 'soft' Italian glass. It has been produced for nearly a thousand years and produces very stable colours. However, I was quickly attracted to working with borosilicate glass, the real 'new kid on the block.'
Borosilicate (which most people know under the trade name of 'Pyrex,' and often called 'Boro' for short) wasn't discovered until the end of the 1800's and commercial produced for laboratory and cookware until the start of the 1900's. For most of that time only clear glass was available. A few colours were added to the palette, but they had to be handmade by the artist before using. It wasn't until the start of 1980's that the first commercial boro colour factory began and an explosion of new and exciting colours became available.
Although there are now more factories and an ever expanding range of colours, it remains a pioneering field. Boro colours are completely different to 'normal' glass colours, having more depth and tone, often with chameleon-like ability to subtly shift their colour depending on the type of light they are exposed to. The high metal content produces very dense colours, and some wonderful metalic effects too. New experimental colours and techniques are still being developed, adding to the excitement of this amazing glass which is part science, part art. Almost everything I now make is with borosilicate.