FORGEover the surface, rather than dumping it all in one
spot, and mix. You’ll find that the surface of the liquid
freezes very quickly, but you need to mix this into the
liquid. It will bubble quite violently – which is a good
reason not to add more in one go! – this is the dry ice
sublimating. Once the bubbling has died down and
there aren’t any hard spots in the liquid, add another
spoonful and repeat. Quite quickly, you will find that
the liquid starts to thicken as it begins to freeze. You
don’t need to freeze the liquid completely, just until
it’s frozen enough that you won’t end up with large
crystals as it finishes off in the freezer. Continue to
add dry ice to your mixture until the liquid is almost,
but not quite, too stiff to stir. You should ensure that
the mix is smooth at this stage, as any lumps in there
could indicate still-frozen chunks of dry ice and you
want to eliminate them at this stage. Transfer to a tub
and put it in the freezer to finish hardening up.
It might be tempting here to dive in and start eating
your ice cream – do not. Despite ensuring that it’s
smooth, it might still have some bits of dry ice in that
haven’t sublimated yet. You need to wait long enough
that all the dry ice has converted into gas. Since your
freezer is about -18 degrees C and dry ice sublimates
at -78, your freezer should easily be hot enough for
this to happen. There’s no clear-cut way of knowing
when it’s happened, and the consequences of eating
dry ice can be severe, so prudence is recommended.
Leaving it overnight should be enough time to ensure
that this has happened, but leave it longer if you’re
not confident all the dry ice has gone. Don’t put the
lid on all the way around as you need a gap to let any
carbon dioxide escape.
Your ice cream is now ready to eat!LIQUID NITROGEN
Liquid nitrogen is, in many ways, a better option than
dry ice. It’s much colder (around -196°C) and as it’s
in liquid form, it mixes better. However, it’s much
harder to get hold of. If you can get hold of some
that’s food-safe, and you know how to handle it
safely, it makes a great ice cream.Below
If you’ve got some
dry ice left, you can
drop a few pellets in
water to create fog
for spooky effects