Saturday, September 17, 2016

Ice 2.0

I've progressed from Clear Ice Ball 1.0 to version 2.0. I still end up with a slight ring around the equator. This is because water expands when it freezes, which pushes the mold apart a bit, resulting in the ring.

This is what the rig looks like fully assembled. The yellow stuff insulates the water a bit further (there is a thermos inside, as you will see shortly), to make the ice form almost entirely from the top.

This is what it looks like underneath the insulation layer. At the top, you can see a black mold. It has a flat end on the outside, but inside the mold is a sphere. It came with a hole in the top, to fill it. I added a hole on the bottom, and then I use the mold upside down, because it fits better that way. The thermos was available with a bunch of designs, including the Batman logo that I went with.

In the morning, I fill the thermos with water, and then insert the spherical mold, pushing it in until the equator of the mold is nearly level with the edge of the thermos (this helps hold the mold together tightly). I then drip water through the top-facing hole in the mold until the entire rig is full of water. Then it goes into the freezer, with the insulating cover, until the next morning. When I take it out, the water in the mold has fully frozen, but beneath that there is only a slight layer of ice, with the thermos mostly filled with cold, liquid water.

Due to the insulation, the ice forms directionally, from the top of the rig down. Ice has a much smaller capacity for dissolved air than water, so as ice forms, air is forced out. When ice cubes form in a normal ice tray, the outside edges of the ice freeze first, and thus the air that gets forced out as the rest of the cube forms ends up in the middle of the ice cube, which is why ice cubes are cloudy in the center. But because the ice in this rig forms directionally, the air that is released as the ice sphere forms ends up pushed out of the hole in the bottom of the mold, resulting in a very clear ice ball.

(The ice sphere appears even clearer in person than in these pics; when the camera phone looks for a point to focus on, it ends up on the frost on the outside of the sphere, which accentuates the imperfections.)

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