Making the Ice which does not Melt
2003 Bill Beaty
During World War II a "mad inventor" by the name of Geoffrey Pyke invented
an interesting substance. It was part ice, part air, and part sawdust.
It was light and strong (as strong as concrete), and it was a fairly good
thermal insulator. In other words, it was super-strong ice which melted
only verrrrrrry slooooooowly. Blocks of it would survive an entire
summer. It could be sprayed into molds with supercooling nozzles where it
hardened in minutes.
Pykrete was a secret weapon. The British intended to build
gigantic aircraft carriers of the stuff. Just make your hull thick
and any torpedo damage will have no effect. If your ship is made of
super-ice rather than steel, you could build mile-long floating islands.
For a permanent ship, add some hoses used as refrigeration coils to keep
melting at all. Unfortunately the war ended before any major use was
made, and today such a large slow target so far from populated areas just
crys out for a small nuke bomb. Only one small test-ship was ever built.
I always wanted to make some Pykrete to play with. Unfortunately there's
a problem. It takes forever to melt, but it takes just as long to freeze!
Mr. Pyke apparently intended to make Pykrete by injecting the water slurry
through cryo-nozzles which would supercool the mixture. The liquid would
be far below 0C, and when sprayed into molds it would harden immediately.
Making a block of Pykerete is not a simple proposition! I never had the
ambition or the weeks of freezing time to mess with the idea.
However, when discussing this on
The Straight Dope and Metafilter forums I
noticed a neat trick. (I haven't tested it, so I don't know if it will
work.) Don't supercool anything. Instead take a cue from nature: big
piles of snow. Big piles of snow melt very slowly. Compressed snow
is a thermal insulator: like styrofoam made of ice. If you wanted to
make some artifical "compressed snow" by freezing some water-foam, it
would take forever to harden. The outer layers would insulate the
still-liquid interior of your ice block, and freezing would halt.
So instead, just make some snow and then pound it down into a compressed
block. It's part water, part air. Styrofoam made of ice. THAT'S IT!
The same thing should apply to Pykrete. Just add wood dust.
Make a piston and
cylinder out of a pipe and a hunk of aluminum. Make
some snow (or finely shaved ice), and
mix it thoroughly with the correct amount of very fine sawdust (supposedly 14%.) Put it in
the pipe and use the piston to hammer it down to form a solid block.
Instant Pykrete! You could even try some simple supercooling: take your
Pykrete block down below 0C degrees in the freezer, then soak it with
icewater to glue the snow together and fill in some of the air gaps.
Practical joke: while it's snowing, blow some wood flour continuously onto
the growing snow layer. (Hmmm, does wheat flour work? Easier to find
As the layer piles
up, it will form Pykrete. That pile of "snow" might still be in your yard
Impractical non-joke: mix snow and sawdust during below-0 conditions and
dump it into the ocean. Repeat. Repeat. A huge floating snow-pile
builds up. The weight of overlying layers
compresses it into a solid.
This is how glaciers are born, but glaciers can shatter, and glaciers can
melt in warm weather.
After you've made a few hundred million tons of the stuff, climb on board
and declare your floating island to have national sovereignty. What
will you name it? Habakkukia?
How about "Pykistan!"