my cat loves doing freeze precip's.  once he separates the nap off into a jar it goes straight into the bottom of freezer (saran wrap sealed). 8 or so hours later he takes a knife to scrape the insides of the jar to knock loose crystals that don't come loose with stirring.  then it is quickly poured through a coffee filter in a funnel. the nap is put back into the original jar to swish around again to be poured through the filter again to get the remaining spice. after he's satisfied with his collection he sets the filter on a couple folded up paper towels to soak up excess nap. and then knocks the spice into a flat glass dish and scrape the paper with a knife. then he chops up and spreads out the spice in the dish to help the nap evap from it. once it quits smelling of nap and smells of spice he usually waits one more hour before gathering it up for storage.