A good casting tip I got off Orchid a few years ago that stands
repeating, is, after you have poured off the water from your buckets
of casting slurry, roll up four newspapers and poke them halfway into
the wet slurry. They will evaporate the water off much faster than
you would believe, leaving you with almost dry plaster for disposal.
You can use the papers for the next bucket. (This tip does not work
if you leave the buckets out in the rain).
(Aren't I good, searchable subject heading)