Any metal casters out there? Question on Sand.

[colu41]

So I recently decided to purchase a small amount of petrobond sand to try casting. And Ive finally come around to build a decent frame? If that's what it's called. Anyways, this sand since I've got it has never really been as "packy" as I've seen online, from videos and whatnot. It does pack when squeezed tightly in my fist, other wise it seems to have more of the consistently of beach sand.

So I tried it out with an official casting this time. It turned out better than I thought it would, but still from day one I thought there was a problem with the sand I received. 

Once it's touched it almost turns to dust, and breaks. Instead of what I've seen, act kind of like a sandy playdough.

Any tips? No pics or videos right now but. If it comes down to it I will get something up.