Zyra's front page //// Fun with Science //// Freezer Fun (Also see Microwave Tomfoolery) //// Liquid Nitrogen Fun //// Site Index

Ice Easter Egg
an Easter Egg with a difference - it's made out of ICE!

Frozen hollow shell, with people mystified about how it was made.

The hollow shell suggests this must be some sort of odd easter-egg, and with it being almost the size of a football, there's something unusual about it. The surprise is that it's made out of ice. A shocking mystery. How could this be done? Some sort of cryogenic conjuring?

I'll explain next how you can make an ice easter egg (not just how to make a NICE easter egg, but how to make an easter egg out of ICE). If you want to spray cake decoration chocolate on it, that's up to you. The tricky bit is how to get a hollow shell of ice.

This is done by consideration of the following:Mystical Significance was Rumoured

1. You can fill a balloon up with air. Easy.

2. More adventurously, you can fill a balloon up with water.

3. If you freeze water in the deep freezer, it turns to solid ice.

4. Now the interesting bit: If you fill a balloon with water and put it in the deep freezer, it will not all go solid straight away. What happens is the outer part gets cold first (like the ice on the surface of a frozen-over lake), and then only later does the inside freeze.

So, you fill a balloon up with water, and put it in the deep freezer, and leave it for a while. How long depends on how powerful your freezer is, but experiment will show what's about right. A few hours, most likely.

You can see when the shell is the right thickness (about half an inch, or up to an inch), because you can see bubbles inside the liquid water which can move about, but of course they don't go through the solid ice shell.

5. Now get rid of the balloon by cutting it off, and then melt a small hole with a warm screwdriver or a drill, and drain out all of the liquid water. (twist it, don't hammer it)

6. The hollow ice shell can go back in the freezer for deployment later. This will also help to dry it.

For people not in the know, there is a distinct mystification about how the item could possibly have been made! Although everyone is aware that water freezes to make ice, it is the hollow nature of the inside that is baffling. Did you carve it? Did you melt it? Did you use liquid nitrogen? Did you freeze-dry it? Etc. You don't need to tell them; it's much more fun to listen to the wild speculations. Also, a good maxim of conjuring is to dispose of the evidence after the trick. Fortunately for this trick you have thermodynamics on your side, which will soon dispose of the evidence for you as the whole thing will melt away.

The mystery is compounded by the fact that the hollow ice shell is complete, and does not have any weld marks (well, apart from where you've bunged up the little hole that you made to drain the water out). Most notably it does not have those circumference marks which a typical chocolate easter egg has.

The completed hollow ice shell has a tendency to remind people of "crystal skulls", those much fabled mysterious artifacts. However, it is much more expensive to make a crystal skull as it requires the skilled use of 19th Century jewellery equipment.

Other points about "Hollow Ice Easter Eggs":

* Yes, it will melt. You can expect that.

* If you're wondering how long to freeze it, it's best to err on the side of caution and freeze it for too long rather than not long enough. At worst it will then be a thick shell, which is in any event better than the whole thing breaking apart and making a mess.

* There is a tendency for there to be a flat bit at the bottom where the balloon has rested on a surface. You can pretend that is a deliberate feature of the design, or, if you are concerned about the flat bit, you could rest the balloon on a cushion in the freezer. The cushion will recover from freezing. (Wrap the cushion in a plastic bag until it warms up, to avoid damp). The cushion technique also suffers from the problem that it insulates the item you are trying to freeze, and that can be a problem. Another solutions is to freeze the balloon resting inside a round-bottomed vessel such as a plastic bowl or a metal colander. Avoid glass.

* Further refinements to the trick may include spraying chocolate, candlewax, or something else on the inside of the hollow ice shell. This is best done when the shell is cold and dry.

* Food colour can be added to the water, making the completed shell a translucent coloured material, resulting in it looking like some weird alien egg/lampshade. This, plus the addition of some unusual smell, such as WD40, disinfectant, or almond essence, can make it seem even more unearthly.

* Other rubber/plastic inflatable items can be used, producing a range of weird results (eg. motor inner tube, something for the weekend, rubber glove, plastic lemonade bottle, beach ball, inflatable alien, hot water bottle, etc). However, remember that with most items it's a one-shot trick and the rubber item in question will be sacrificed to achieve the result. Larger items will require longer in the freezer. I would guess the motor inner tube is probably the next step to progress to after the balloon full of water, as you can use one that has a puncture with a temporary repair, and the rubber can be recycled as stretchy string (useful bungee cord) after the ice structure has been completed. Plus, the result of the freezing a car inner tube full of water would be toroid of ice, and if left for the correct time, a hollow toroid of ice!

* If you'd prefer to get a quality chocolate easter egg without all this messing about, there are some nice ones available at Thorntons