Mercerised cottons and Unmercerised cottons
The article about the yarns in our last newsletter evoked a lot of interest and people started asking more questions. One of them is about merceised cotton. What is mercerized cotton? Is un-mercerised cotton a better choice for towels as it may absorb more moisture?
Will try to answer these questions now:
Mercerisation is a chemical treatment. It is done on cotton either in yarn form (hanks) or in fabrics. The process imparts a greater affinity for dyes. It also improves absorption, improves strength, and gives a nice luster to cotton.
The cotton fibre in its natural form has a kidney-shaped cross-section. During mercerization, the yarn is held under tension and immersed into sodium hydroxide bath. This process ‘swells’ the fibre and makes it rounder. The ‘swelling’ makes the fibre absorb more – be it water or dyestuff. Interestingly, mercerized yarns retain the brilliance for many washes compared to un-mercerised yarns. The change in shape from kidney-shaped to rounder shape make the fibre reflect more light, thereby giving a nice luster.
Generally, mercerization is done in conjunction with another process- gassing. Actually, the yarn is gassed first before being mercerized. Gassing is a process where the yarn is passed through a flame (yes, you read it right !) quickly to ‘burn’ the protruding fibres from the surface of the yarn (called hairs) thereby making it smooth. This process also greatly helps in increasing the lustre of yarn.
Next question: Is un-mercerised cotton a better choice for towels as it may absorb more moisture?
There is a general feeling that un-mercerised cottons absorb more than mercerized cottons and hence more suitable for towels. Not really. As explained above, mercerised cottons absorb more.
So, which yarn is then better for weaving a towel? Well, it is a personal choice. If you want a ‘smooth’ and ‘bright’ towel, you can opt for mercerized cotton. If you want a ‘softer’ & muted towel, you can choose the un-mercerised cotton as the ‘hairs’ are still retained.
Interestingly, that leads to the next logical question: Why then regular crochet cotton threads and cotton sewing threads are not absorbing moisture? After all, they are also mercerized.
The reason why they are not absorbent is that they are very tightly twisted, drastically reducing the absorbency properties. So, the towels woven with them won’t be as absorbent as regular yarns.
Incidentally, our mercerized cotton yarns have a nice twist balance. They are not tightly twisted and so they are good for weaving towels and napkins. When crocheting, these yarns behave well don’t give a ‘wiry’ feel to your projects, which usually happens with tightly twisted crochet threads.
We carry a range of mercerised cottons in counts 5/2, 10/2 & 20/2 and also un-mercerised cottons in 10/2. While count 5/2 is suitable for weaving place mats, cushion covers etc, count 10/2 is good for towels and napkins. 20/2 is fantastic for weaving stoles. Crocheters buy our mercerised cotton 5/2 for doilies and mercerised cottons 10/2 for crocheting blankets.
Thank you for such a great explanation of mercerized vs unmercerized cottons. As a relatively new weaver, there are so many myths out there. Be well…
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