Plastic container or bowl that your apple can fit inside
Clear nail varnish or PVA glue (optional).
What to do
Peel the apple. An adult should help younger experimenters.
Using the teaspoon, carve out the features of your mummy's head (and we mean an Egyptian mummy, not your mum!) in the apple.
Mix about 1 part bicarbonate of soda to 5 parts salt so you have enough to completely bury (see the next step) your carved apple. Now totally immerse your apple head in salt and bicarbonate of soda.
This is easiest if you pour in some of the salt and bicarbonate into the container, place you head on top and then pour in the rest around the head.
Leave your head alone in the mixture for several weeks.
You can then remove the apple head from its salty tomb. You should have a wonderfully dry, wrinkled apple mummy skull.
If you are feeling macabre you can decorate it with button eyes and some human hair clippings.
You can also varnish your mummy head or coat it with PVA glue which will help it last for a long time. Apply the varnish in a well ventilated area.
What's happening?
The salt around the apple is an example of a desiccant - it absorbs the moisture in its surroundings, in this case the apple.
Bacteria and mould thrive in moist environments, and drying out the apple prevents bacteria from causing the apple to rot.
Adding a coat of varnish helps prevent any moisture from getting inside the apple, and you can keep your shrunken head for archaeologists to find in the future.
Applications
Salt was one of the ingredients that ancient Egyptians used to make mummies. To mummify a body, Egyptians would remove the brain and all the internal organs after a person had died.
A mixture of natural salts called natron was then stuffed inside and around the body. Natron salts were native to the area, and not unlike today's bicarbonate of soda.
After days of drying with the desiccant natron, the body was wrapped up with linen soaked in resin. The resin hardened and acted in the same way as nail varnish by stopping moisture getting inside.
Other easily available desiccants are silica gel packets (the ones labelled ‘do not eat') and uncooked rice. Why not try the shrunken head experiment using other desiccants to see which is the most effective?
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