Two-bucket ice lanterns

Two-bucket techniques and their variations

Instructions for making ice lanterns have commonly described a process with two nested containers.  I have largely stopped making them this way because there are easier methods, but there are times when the two-bucket technique is useful.

Often, when making ice lanterns, variations of the techniques present advantages and disadvantages.  A neighbor who likes to make very large ice lanterns introduced me to this method, which uses a specific IKEA wastebasket, the "Fniss" translucent one.  It releases the finished lantern easily from the mold, and it resists cracking.  The inner "bucket" is a plastic yoghurt container mounted on two wooden supports.

Making a two-bucket ice lantern
in an IKEA wastebasket.  The inner
"bucket" is suspended from two wood
supports and has to be weighted down
to keep it from floating out of the water.
Any weight could be used, but here
an Arctic Ice Lantern has been set
on top of the water-filled mold.

With this technique, the opening in the ice lantern is created by the inner bucket, which keeps a channel open into the core of the ice lantern.  The bottom will tend not to freeze solidly if it is too well insulated by warm soil or by snow.  If a well-frozen bottom is needed, it helps to freeze the first inch of water before adding the rest.

Filling an IKEA wastebasket using
the two-bucket system for making
an ice luminary

Like many of the other techniques that I use, this one requires keeping track of how the freezing process is going, because the hollow in the lantern is produced by pouring out the un-frozen water in the core.  (This differs from a two-bucket method that nests two buckets of nearly the same size  and freezes the water solid between them.)

What freezes -- and what doesn't.  The Arctic Ice Lantern uses
the insulation provided by its indentation and the surface it rests
on to delay freezing of the base of the mold.  In contrast, the
two-bucket technique maintains an opening in the top of the
mold by protecting the center with a second container.

When the wall appears to be thick enough, the inner bucket is loosened by putting some hot water into it.  The water can then be poured out of the core, usually outdoors, because this is messy.  To release the ice lantern from the mold, it is usually necessary to run some hot water over the mold, which I do in a bathtub, or the mold can simply be left inverted in a warm area, and it will release in 5 to 10 minutes.  Setting it over bubble wrap cushions the dropping ice lantern against possible cracking, but usually this is not a problem. 

Very often, the top of the ice lantern freezes with lumps and unevenness.  This is due to expansion and contraction of the water before and during freezing.  Water becomes denser as it cools down to 4 degrees C (39.2 F), then begins to expand and be less dense when it nears the freezing point.  All of the water in the mold is cold and dense before it starts to freeze, but the ice that forms on the walls and top of the mold begins to expand and press on the water in the core.  Any weak spot in the ice forming over the open area of the mold can open a tiny channel for the water to leak through.  Where the water wells up, it freezes in irregular bumps and ridges.  Depending on the speed of freezing and the initial temperature and density of the water, the top may be very irregular or nearly smooth.  This process can be controlled to some extent by occasionally drilling or punching a hole in the surface to relieve the pressure.

Uneven freezing of the top of the
ice lantern made with the two-bucket
technique in an IKEA wastebasket.
The bottom didn't freeze solidly
enough to hold a candle, so the
light is coming up from the base.

The base of the mold tends to freeze slowly if it is sitting on snow or bare ground.  The net result is often an ice lantern that easily melts through the base and has an irregular top.  I made several of them before deciding that this form was better if used differently. 

This is one of the better two-bucket
lanterns made in the IKEA Fniss
wastebasket, but the top still
shows some irregularity

The flaws in this mold are managed by turning it upside down and using it as a base for globe ice lanterns.

When the irregular upper surface
is turned to make a base, and the
bottom becomes the top, the IKEA
Fniss wastebasket ice lantern serves
as a beautiful and effective support
for a large ice globe luminary.

Making two-bucket ice luminaries by closely nesting two buckets and letting the water between them freeze completely (with no liquid core to pour out) is another way to produce ice lanterns.  It allows for freezing decorative items in the wall, and it doesn't require monitoring the thickness of the developing ice, but it does require attention to positioning and stabilizing the inner bucket.

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