It does not have to be dry. Don't use a blender as it can bruise the trics, and you can also end up with to much veg in the hash. THC not being water soluble means that it will sink to the bottom and not dissolve. In chemistry, I guess you can call the THC a precipitate, as it falls to the bottom.
Instead of using a blender you just want to agitate it enough to snap off the trics. And yea, invest in some bubble bags man.