Asbestos!
Well, I could not help myshelf arguing on asbestos!
Did u all know that less than 10 years ago all of us were poluting our beloved earth using brake pads containing lots of asbestos?
Not to our knowledge though, but the ones who did the decision making, decided that asbestos is no good for brake pads just 10 years ago...
I use berrylium dioxide insulators in my aleph30 and these are the best ever tried(salvaged from an old UPS), but u can order also aluminium oxide insulators with comparable performance and more user friendly.
Moreover, BeO2 insulators are safe enough, provided u use plastic gloves and that u do not swallow or breaking them, as toxic is only their dust. For the ones who cannot access such materials mica are very, very good, too.
Sincerely,
Panos