http://www.forrestrace.com/brass-glass-3/
what is the difference between a glass and brass guitar slide?
It depends on a few things. What gauge strings you’re playing, for one. If you’re playing with relatively light strings, then glass sounds best because it sustains well (if its thick), it’s very smooth on the strings (less sliding noise), and has less harmonics than Brass. However, when playing slide, you need to play with as heavy strings as you can tolerate so that you don’t bang into your frets and make a bunch of unwanted noise, and so you can achieve maximum sustain. So if you play with a heavier string gauge, brass is best because you get an awesome growl tone and real good sustain.
The thing to remember is that the weight of the slide is more important than what it’s made out of. The heavier the slide, the better the contact with the string, the clearer the tone, the longer the sustain. A thin lightweight slide, whether it’s made out of brass or glass, is going to give you poor sustain and mosquito-like tone.
I myself prefer the sound of brass, but I use porcelain because it will absorb moisture from my finger and is more comfortable. I also have a heavy Dunlop glass slide called the “215″ (or something that) that sounds great on an electric but horrible on an acoustic. So, it’s really just a matter of trial and error for you.
#341 Philip Glass – Brass Sextet (1962-1964) (Fragmento) – mov #1 (Hymn)