How to test fibre content of yarn

How to test fibre content of yarn

How to test fibre content of yarn using bleach

We are frequently asked the question of how to ” test fibre content” . We decided to write this article to help you.

A relativity easy procedure which will indicate if the yarn is from an animal, plant or is synthetic. Pour a little household bleach into a saucer or small bowl , next cut off a short length of your yarn and gently drop the piece of yarn into the bleach.

Wait for a minute or two and this is what happens –



  1. The bleach begins to gently fizz or bubble then the yarn comes from an animal , also silkworm yarn. The yarn will usually dissolve in less than an hour.
  2. Plant fibre yarn. The yarn will start to lose colour and goes white, .
  3. The yarn does nothing, eg no bubbles. This will indicate it is an acrylic or polyester yarn, will not be altered by the bleach. The yarn may lose some colour.
  4. If the yarn starts to bubble but it does not disappear completely it is likely to be a blend of wool or silk with acrylic.



Note: Also Remember to practise caution & safety when using bleach. BECAUSE bleach is a dangerous product & can blind if it splashes in the eyes.

Be sensible.

We do not recommend the burn method to test yarns for several reasons:

  1. Some artificial yarns may contain fire retardants as such they won’t burn.
  2. Wool does not burn easily, this could also be confused with a yarn that may contain fire retardants.
  3. Fire can be extremely dangerous and can take hold faster than many people realise.
  4. Smoke is a carcinogenic (causes cancer).
  5. Some artificial yarns contain very dangerous chemicals when burned.
  6. The Fire Dept state this is a no no, because apart from being dangerous it can cause false alarms in house and apartments.


Sheeps Wool is Flame resistant
Wool is the only fibre that naturally resists flaming.

Unlike many artificial fibres which can melt and stick to the skin when on fire, wool usually smoulders or chars instead of bursting into flame. Although wool will burn under intense fire, it normally self-extinguishes when the flame source is removed.
For safety reasons, Some airlines use wool or wool blends for the upholstery fabric on their seats. Wool is often favoured by the military


If you have any questions or queries contact Xenaknits.



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