I did an experiment today trying to press some dried powder. All I can say is that you all must live in the desert! I dried the powder on the dashboard of a car. It was completely dry. I tried to make a couple of pucks amd they were brittle and crumbly. Now, without drying the powder, I'm able to press it just fine with only the moisture in the atmosphere. That's with it being bone-dry here. We haven't had rain in a couple months (normally a daily occurance around here). Grass that normally grows 1" per day, that grass hasn't grown in months. The ponds are 4' below normal. That's how dry it is here and I've been able to press pucks just fine.
I took this batch, crumbled it with my hands, gave it a squirt of 70/30, swirrled it around, and put it on the workbench so it can equaliže with the atmospheric pressure. When it dries, I'll press it it.