What is the ICEBOX?
The ICEBOX was invented by experienced winter mountaineers, who have built and
camped in a variety of snow shelters in Colorado’s mountainous backcountry. For
many years, they have used the basic concept of a concrete form to construct the
walls of rock-roofed snow caves. Transferring the idea to igloo construction,
they developed the igloo slip form that became the ICEBOX.
Unlike digging a standard snow cave, you will remain relatively dry as you build your igloo. The ICEBOX has been designed to produce a dome-shaped igloo every time. The flying buttresses of European cathedrals are constructed on this same principle — it is self-supporting in that the pressure pushing in is equalized by the pressure pushing down. It will not collapse or bulge outward as will a hemispheric-shaped igloo. While a standard snow cave will rarely last more than a weekend, you can expect to use your ICEBOX igloo in reasonable safety for most of the season.
“You can’t even make a snow ball
with this snow.”
For the last 10 years or so we have paid attention and tried to figure out what
underlying theory or technique fit the formula for packing all types of snow.
What we have come up with is a description of a packing technique that works in
all conditions.
Try this test: Squeeze some snow by holding your hands in the “prayer” position.
Squeezing gently, hold that pressure for four seconds and release evenly. The
amount of pressure needed is very little and you will feel it build up in your
hands. At some point, the snow will “lock up” and stop moving. This is where you
want to stop increasing the pressure.
Now apply more pressure. You will feel the snow move and “lock up” again. If you
hold at this point for four seconds and release evenly you will have a chunk of
snow in your hands. You can continue to increase the pressure and feel these
steps of “locking up” at various different pressures. Not being able to release
evenly is the problem with the higher pressures. With all the years of packing
snow and now using the ICEBOX for two years, we have come to recognize the
pressures required when packing. For another experiment, push on a bathroom
scale with your flat hand. You should approximate six to seven pounds of
pressure when packing. More than this and you run the risk of moving the ICEBOX
form, therefore causing fractures in the block you are building. Practice and
patience will help you perfect this technique.