Your handmade string makes a great bracelet.
Most clothes are woven from thread, then sewn together with thread. While there are now many human-made fibres, cotton is the most widely used of the natural fibres in clothing. So why not try spinning your own cotton thread, and learn a bit more about how clothes are made?
You will need
- Clean cotton balls
- Pen with a pocket clip
- Lots of patience
Note: This activity is hard to get right on the first try. Don’t give up! You’ll get better quickly, and you’ll soon be spinning thread like a champion!
Spinning a thread
Most cotton balls are made of a long piece (wad) of cotton that’s wound around itself. See if you can find the top layer and unwind it to reveal the long cotton wad.
Gently tease the cotton apart a bit. If you look closely, you’ll notice most of the fibres run in the same direction, along the wad.
Hold the wad with one hand. With the other hand, pinch the end of the wad between your thumb and pointer finger.
Pull on the pinch softly, and then twist the cotton by rolling it between your thumb and finger. Once you’ve started twisting one way, you need to keep that direction for the entire pulling process.- Alternate between pulling more cotton into your string and twisting it to make it strong. It might come out lumpy at first, but keep at it.
If you accidentally pull too hard and break the thread, all is not lost! Untwist the bit that broke, and lay it on top of a bit of the wad. If you twist carefully, you might be able to get the thread to connect to the wad. If it doesn’t work, just start again with a new cotton ball.
When you’ve got string about 50 centimetres long, you’ve got enough to move onto the next step.
A strong string
Tie one end of the string to the pen clip.
You can now add twist to your thread by rolling the pen on your thigh. Remember to keep hold of the loose end of thread, holding the string tight!- You need to put quite a lot of twist in the thread. When it starts to pull back and wants to coil into lots of little springy shapes, it’s about ready.
Grab the middle of the thread with your mouth. While keeping the middle of the thread in your mouth, bring your hands together. Transfer the pen and the loose end to just one hand.- Pass the middle of the thread from your mouth to your free hand.
Keep the thread tight and slowly twist both ends together, the opposite way to usual. The thread will naturally want to twist, so follow the string’s direction.
Now you have a piece of string you can do lots of things with it. Maybe you want to test how strong it is by hanging heavier and heavier weights on it. Or maybe you could add a few beads and make a bracelet!
What’s happening?
Cotton is made of lots of tiny fibres. If you pull a cotton ball apart, you’ll find that they are very skinny and quite short – maybe two or three centimetres long.
These fibres aren’t stuck to each other – they are all individual pieces. What’s holding them together is tangles and friction.
When you unroll and stretch a cotton ball, you start untangling the fibres, which is why the cotton ball becomes so fragile.
When you start twisting cotton, you do two things. First, the fibres get wrapped around each other, which helps to tangle them again. Second, as the twist gets tighter, the fibres are squished together. As they are pulled tighter and tighter, the friction between them increases. Both of these things make your thread stronger.
The final step, where you fold the string in half, is called plying. By doubling up the string, you make it twice as strong. If you get the twist just right, you can make string that doesn’t unwind – this is known as balanced string.
Your string has two strands, so it’s known as two-ply string. If you go to a craft store, you might find three or four ply yarn, and embroidery thread is often six ply.
A brief history of spinning
Spinning is an ancient art. Historians don’t know exactly when people first started spinning thread, but it was at least 20 000 years ago.
We don’t have any surviving string from that time, but we do have sculptures of people wearing string skirts, and the earliest sewing needles also come from around the same time.
If you’re after more science activities for kids, subscribe to Double Helix magazine!
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