Bendy Bones
Fascinating Food / Body Beautiful

Tie chicken bones in knots using simple household ingredients

Age range 7-14


• Two large glass jars
• Some small, long, thin chicken bones (Instructions for cleaning them thoroughly are below.)
• An old saucepan
• Washing soda (sodium carbonate)
• Rubber gloves
• Bleach
• Vinegar




• Wash the bones and pick off as much meat as you can, then put them in an old saucepan with warm water and add a teaspoon of washing soda.
• Simmer (don't boil) the pan for at least ten minutes, and then see if you can remove the rest of the meat. If you still have some meat left on the bones, carry on simmering until you can take it all off.
• Now put the bones in one of the glass jars. Put on your rubber gloves. Fill the jar with water and add a capful of bleach. Leave the bones in this mixture until the next day, then remove the bones and pour the water and bleach mixture down the drain.
• Put your clean chicken bones in the jar or glass and pour in enough vinegar to cover them. Leave them somewhere safe for 5-7 days. Change the vinegar every two days.
• Remove the bones from the jar and try bending them. What happens?
• You're now ready to practice your bone-bending, knot-tying technique! Once you've finished playing, tie the bones up into a tangle (or arrange them into a pattern of your choice) and leave them out to dry. You can fix them in place using pins or adhesive if necessary. After a few days they'll go hard again, leaving them permanently bent.


You probably know that bones contain calcium. This is found in the form of calcium carbonate, which helps give bones their hardness. Calcium carbonate reacts with acids. Vinegar is a weak acid, so when you put the bones into the vinegar the calcium carbonate starts to react with it.

You can even see the reaction taking place - if you observe the bones at regular intervals when they're submerged, you'll see small bubbles forming on their surface. These are bubbles of carbon dioxide gas, formed as the calcium carbonate breaks down.

Without the calcium carbonate, the bones become much softer and are less rigid than before. Hey presto- bendy bones!

Leaving the soft bones out in the air for a while allows them to harden again (although this isn't a simple reversal of the reaction with the vinegar).


Bobby Cerini at Planet Science



Bleach is an irritant for eyes and skin, so make sure you wear gloves when using it. If you get any on your eyes or skin, wash it off with lots of cold water.