Since our last chat with Magnus from TotsBots, we have realised how much there is to know about textiles and woven fabrics, and how little we do know! So to fix this we decided to invite Lindsey, lecturer in woven textiles at the University of Manchester, who very kindly joined us for an hour all about fabrics!
Lindsey: Hi all! I’m a lecturer of woven textiles at the University of Manchester and I teach weave from both a design and technical point of view. My research interests are multilayer wovens, flat and shaped fabrics using various yarns and manipulating their inherent characteristics. I am a trained designer of wovens, but with on hand experience of textile composites due to PhD and industrial experience in this field. I like to mix design (aesthetics) and technical performance within fabric construction.
@Lindsey: Can you explain a bit about what ‘wovens’ includes? I’m guessing it’s not just clothing fabrics like tweed!
Lindsey: Wovens just means any fabric that is constructed using a loom, whether hand loom or fully automated industrial weaving. So from tweed, other fashion fabrics to carbon fibre fabrics for the automotive industry.
@Lindsey, I don’t know how much you know about modern reusable nappies, but is it likely that some of the fabrics used in those are woven then?
Lindsey: From my basic (very basic) understanding of disposable nappies, I think these are possibly non-woven’s. Non-woven’s being constructed via the placement of fibres and felted somehow to fuse together to form the material. Traditional cloth nappies I would assume are woven.
@Lindsey: So the fabrics commonly used on cloth nappies would be woven?
Lindsey: The outer nappy will be knitted, due to the elastic stretch characteristics of the interlooping of knits. The inner bit, the lining, could be non-woven or woven with an outer coating to ensure waterproofing. Old, traditional, big squares of fabric to wrap around the babies bottom would be typically woven.
Q: With nappies we are particularly interested in two main things, how much they absorb, and how well we can get them clean. Can you say anything about how textile construction might affect those two things?
Lindsey: If using woven textiles, maybe as an outer layer (so the fabric that could have exciting creative designs) or even the inner layer (the waterproof lining), I would recommend a very tight dense weave to limit the void areas, the areas of space around the weft yarn as it interlocks with the warp yarn. This way when applying a coating to ensure it is useable there is even distribution across a greater area of fibres. If you use a non-woven, so think felted fabric, there are no real void areas if the non-woven/felted fabric is dense. Any woven, non-woven, knitted fabric can absorb at the correct consistency, or permeability the main key component is the fibre/yarn used in the manufacture of the constructed textile process chosen. I’m not too sure on cleaning. I would recommend someone with a chemistry background!
@Lindsey: So the fibre/yarn used in the manufacturing process is what mainly affects absorbency, am I understanding that right? If I am, what differences are there between fibres that affect this?
Lindsey: Yes – Looking quickly online reusable cloth nappies, it seems like they are made from cotton, wool, bamboo and hemp. There are varying qualities of each of these four fibres and varying counts of yarn. In simple terms, the count of yarn is the fineness or thickness of the yarn. With cotton it can be processed in many ways, bleached, mercerised, non-mercerised. Each is a chemical process that imparts some form of outer coating on the cotton fibre in a yarn form that will affect the absorbency of either dyestuffs or other coating for functionality, such as nappies.
Q: What is mercerisation of cotton?
Lindsey: Mercerisation of cotton is typically the treatment to the cotton yarn using sodium hydroxide to give the cotton both strength and a lustrous appearance. Non-mercerised cottons will be dull and weaker in comparison
@Lindsey: So does mercerisation make cotton more or less absorbent?
Lindsey : Both mercersied and non-mercerised cottons are used in fashion garments – The process is about appearance and strength. However, mercerised cotton does become more absorbent.
@Lindsey: would mercerised cotton be safe against a babies skin?
I see no issues with it being used against the skin, as it is used in fashion textiles.
Q: What is the interplay between the absorbent materials and the outer PUL layer? Is it likely that a PUL layer may trap more bacteria or decrease washability as opposed to a two part system with a fully removable cover?
Lindsey : Yes, it is possible (both waterproof and breathable) but this is where someone rather more scientific than me would suit your group!
Q: Do bio powder enzymes really eat away natural fabrics?
Lindsey: Unfortunately I don’t know, but I have a contact at Leeds University who may like to help.
@Lindsey: That would be great Lindsey, thank you
Q: We spoke to a manufacturer who just touched on fabric construction, he said ‘We prefer to use piled fabrics for absorbency (towelling) as they give a larger surface area per cm’. But I imagine that gives more crevices that dirt can get trapped in, making it harder to clear. We have talked to some chemists about detergents, but I’m wondering if the construction of a textile could make a difference.
Lindsey: I agree with you – The construction of a textile very much impacts on its performance, absorbency, ability to remain clean, so limit retention of dirt. This is in line with the fibre/yarn type used. I understand the surface area per cm2, but other constructions could be considered, or designed.
Q: When I lived in Italy in the Noughties there was a massive health scandal about Chinese pants causing vaginal cancers because the manufacturers were reprocessing waste products into fibre and making cloth which was then used to make cheap market clothes. Have you ever heard of this type of problem in the UK and are there any standards that have to be met for fabrics manufactured outside the UK?
Lindsey : All countries have their own equivalent to our British Standards, and unfortunately some are sub-standard. The pants would have to have high levels of carcinogenic fibrous materials to cause this. As with carbon fibre, asbestos, it’s down to the nano-scale fibres/particles that can be absorbed, swallowed or inhaled that impacts upon the health.
@Lindsey: Thank you for this chat, I had no idea fabric was as complex!
Lindsey: No problem at all – I hope I was of some help! Interesting project… Has given me food for thought, with regards to surface area within woven textiles per cm2!