Coarse is generally 1/4 inch or better.
Most Perlite is dusty crap with very little coarse particulate. I rinse my Perlite if it is inferior, and keep only the stuff over 1/16 of an inch....

Josh

FWIW, large bags of course perlite are usually available at hydroponic stores.

Ed, that used to be the case at the local hydro shop....they were carrying Sunshine #4 Coarse Perlite - 4 cu. ft. bags for $20 - and zero waste. The stuff was clean and beautiful. Then, the owner started buying the cheaper stuff, and that was the end of that. I made the mistake of getting the new product, not knowing that it would be half-dust. Same price, half the product....

Josh

I found a hydro place selling perlite the size of small marbles. Are those usable for anything? Anybody had any luck breaking up perlite into smaller chunks?

ox

good for orchid mix

dave

I see the BB size reference quite often on GW. Does it mean 4.57 mm (0.18 inches)?