it's been a long time since i used this method. i think a standard residential window pane using tempered glass would be about right. too heavy and you could have the glass make an imprint on the grooves at the high spots. you are better off doing it twice than getting glass that is too thick.
a 12" x 12" window pane has sufficient weight to work.
as far as shattering the glass......make sure the glass is not cold to begin with......run it over increasingly warm water and then thoroughly dry it.
a 12" x 12" window pane has sufficient weight to work.
as far as shattering the glass......make sure the glass is not cold to begin with......run it over increasingly warm water and then thoroughly dry it.