Does someone know a good website discussing various aspects of glass and caps? Let's say the difference between level 1 and level 2 glass, or class A and class B glass, and the difference between Teflon and silicone caps?

Thanks a lot in advance.

Try this web site. www.cmcissues.com/toc.htm and then follow with Packagin.

This might be a good place for your search
Hope this helps!
Ananda

Thanks a lot for the web link. However, it is fee based. Is there any free alternative?

Thank you very much for your help!