I see a lot of "2 parts this to 1.5 parts that" but generally on these forums are you guys talking weight or volume? I have my base materials ready but do not want to screw up my first mix, perlite is very light, so by weight it is 3-4 times more volume than the sand or fireclay of the same weight.

 

Thanks in advance.

Volume.  Kind of like mixing a drink.

I second that  ("Unless otherwise specified")

ok, cheers