All that glisters - collapse effects with metallic yarns and wires
As weavers, we tend to think of metallics simply as yarns we can use to add a bit of sparkle. As spinners, we probably don’t think about them a lot at all. But through happenstance three or four years ago I discovered things weren’t quite that simple and that paying a bit more attention to them could deepen our understanding of how yarns behave and give us more tools to play with.
By chance I discovered that a particular hand-made Japanese silver yarn from Fibrecrafts behaved in an extraordinary way when wet. I was able to exploit its strangely sculptural properties in some yardage pieces and with assistance from Ann Richards was able to arrive at a possible explanation, described in Journal 231, Autumn 2009 in Moonlight on the Water.
In essence, it seemed that the yarn had two properties that were causing the effect. Firstly, the yarn was somewhat unbalanced – it had a flat silver strip wrapped quite tightly in a Z-direction around a barely twisted filament rayon core, and, being unbalanced, it had a tendency to behave like a singles yarn. Secondly, the rayon core swelled when wet, pushing against its silver wrapping and causing it to distort.
The conventional wisdom is that metallic yarns are stable, or passive, but this was so clearly not the case with this yarn that I started to investigate the whole area of metallics further. Without any very clear idea of what I was looking for, I amassed a collection of wires and metallic yarns of all sorts, and made as many observations as I could about their structure. I prepared a warp of 60/2 nm spun silk using a straight draw threading on 8 shafts and wove two sets of samples using each of them as weft. The first set was plain weave, the second set was a 3/1/1/3 twill (lifting sequence 1-2-3-5,
2-3-4-6 etc) to give both warp- and weft-faced areas, so I could judge whether weave structure was influencing any 3D behaviour. All the samples were washed in a front-loading washing machine on a 40°C one-hour cycle and air-dried.
On the basis of these (very scruffy-looking!) samples five clear categories seemed to emerge:
- glitter yarns such as Lurex®
- fine metal strips
- yarns plied with a fine strand of wire eg silk/stainless steel, copper/bamboo
- core-wrapped yarns
1. Glitter yarns such as Lurex®
These are the yarns that probably most people think of as ‘metallics’, although actually they don’t contain any solid metal at all – they are usually a fine strip of polyester with a metallic coating (think of them as polyester sprayed with metallic paint). They may be supported by fine nylon threads to give them more strength; if so, there are typically two threads that wrap around the polyester in a figure of eight, interlacing as they do so and resulting in a completely balanced yarn.
All the samples with these yarns stayed completely flat. They are the stable, passive yarns of conventional wisdom.
I only sampled with one of these, a strip of aluminium from Japan. It was completely stable and it’s hard to see why it would be otherwise unless coated in some way. But generalising from a class of one is not exactly scientific.
These are metal drawn out in a single continuous strand with a round profile.
I sampled with stainless steel and with coated copper in two diameters, 0.1mm and 0.2 mm. (0.1 mm = 100 microns.)
The results from these were completely surprising. Without exception they formed strong, regular undulations, and
I have no idea why. It may even be something to do with the action in the washing machine. Clearly this is an area for further sampling, but it’s a lovely effect to exploit.
4. Yarns plied with a fine strand of wire
These are regularly constructed yarns, either singles or plied, which are twisted with a fine strand of wire. I sampled five yarns of different fibres and thicknesses, all containing a strand of stainless steel.
The results with these yarns were not completely consistent. Four of them showed some level of ‘crêping’ – a tendency to form furrows in the way that overtwisted yarns do – although the effect was typically larger scale. I also noted that the crêping seemed to form a slightly different pattern in the twill samples, reflecting the weave structure. But one of them, the viscose/stainless steel, behaved like a wire in both samples.
I looked closely at the yarn structure to see if I could identify something there that might be the cause. There is quite a lot of variation in the way these yarns are constructed. The most commonly available, the wool/steel and silk/steel blends, are both made by taking a standard balanced yarn, spun S and plied Z, and plying it Z with a strand of stainless steel. The result is an unbalanced yarn, and this is obvious when you work with it – it will curl around on itself, and the corners of the woven cloth curl.
At first sight the construction of some of the other yarns seemed more balanced, but when I factored in the relative number of twists at each stage of the construction, it turned out that actually none of them were balanced. So that would explain the crêping, although it doesn’t help explain why the viscose behaved differently.
I then considered the diameter of the wire component. Unfortunately I don’t have the precision equipment that would be needed to measure the diameter of wires this fine. The silk/steel and wool/steel I know are made with 50 micron stainless steel. The wire in the viscose yarn is noticeably thicker.
So a reasonable working hypothesis is that the wire-like undulations in the viscose/stainless steel samples were caused, at least in part, by the thicker diameter of the wire component.
The tightness of the twist – the turns per inch – may also be significant. There were only five tpi in the viscose, very much lower than the others. It is also possible that the relative lack of pliability of the viscose element compared with the other (finer) yarns played a part.
5. Core-wrapped yarns
These are yarns that have a fibre core which is completely, or almost completely, covered with a flat metal strip wrapped spirally round it. The Japanese silver yarn that first aroused my interest in this area is a core-wrapped yarn, and many metallic embroidery yarns are core-wrapped.
Again, there is considerable variety in the detail of composition and construction of these yarns, and it can be very difficult to analyse the core. As far as I could establish, I looked at yarns with rayon, cotton and paper, but silk is also often used.
The core may be loosely twisted filaments, plied yarns, or twisted paper. The wrapping may be applied in the same direction or the opposite direction, giving all sorts of degrees of balance or imbalance in the yarn. The wrapping may abut closely, creating a tight sheath around the core, or it may have gaps between each turn, leaving space for the core to expand without distorting the metal.
Not surprisingly given all the variables, the most varied results came from this category and these yarns are possibly the most interesting for further investigation. Most of them displayed some degree of undulation, similar to the wires but less smooth and regular; many of them also displayed a degree of collapse, similar to the plied yarns. Judging from the twill samples, the pattern of collapse seems to be affected to some extent by weave structure.
There seem to be a number of factors at play:
1. The balance of the yarn
An inherently unbalanced yarn will be likely to collapse.
2. The fibre used as the core
A viscose core, most notably rayon, will absorb water and swell when wetted out.
3. The pliability of the core
A thick, relatively non-pliable core will make the yarn behave like wire.
4.The tightness and abutment of the wrapping
If the wrapping is tight and closely abutted, and the core swells when wet, the torque that is created pushes the yarn into 3D shapes in the areas of least resistance, which is why weave structure plays a role.
The research that I have carried out so far certainly raises more questions than it answers, but it is exciting to become aware of types of active yarns in addition to stretch, overtwisted and soluble, and to think how to use them to best effect. There are no hard and fast guarantees, but the following generalisations are a good starting point for sampling:
- Wires are likely to form undulating waves, at least if finished in the washing machine.
- Any yarn with both a fibre component and a metal component is likely to cause some degree of collapse if it is pliable enough to do so.
- If it is not pliable enough to collapse, it is likely to form undulating waves if finished in the washing machine.
- Core-wrapped yarns, especially with a viscose core, are likely to distort as well as collapse due to internal pressure.
More sampling will probably bring more surprises and probably some exciting exploitation of these yarns too.
Yarns sampled in the research
Silver metallic Lurex® (The Handweavers Studio)
Fine gold metallic (The Handweavers Studio)
Fine metal strips
Japanese aluminium strip (gift from the Kawashima Textile School)
Stainless steel 0.1mm (Scientific Wire Co.)
Coloured craft wire 0.1mm (Scientific Wire Co.)
Coloured craft wire 0.2mm (Scientific Wire Co.)
Yarns plied with fine wire
Wool/stainless steel (The Handweavers Studio, Habu)
Silk/stainless steel (The Handweavers Studio, Habu)
Cotton/stainless steel (Textura Trading)
Merino/stainless steel (Textura Trading)
Viscose/stainless steel (Textura Trading)
Japanese metallised silver (Fibrecrafts)
‘Heavy Metal’ (GIF, no longer available)
Old French silver yarn (gift)
Silver embroidery yarn (gift)
Blue embroidery skein (Texere)
‘Rajmahal copper handsew’ (gift)
The yarns sampled in the research described above came from the following suppliers:
The Handweavers Studio, London www.handweavers.co.uk
Textura Trading, USA www.texturatrading.com
Habu, USA www.habutextiles.com
The Scientific Wire Company, Essex www.wires.co.uk
GIF, Denmark www.yarn.dk
Fibrecrafts, Guildford www.georgeweil.com/fibrecrafts...
Texere, Bradford www.texere-yarns.co.uk
Another supplier who specialises in wires and metallics is:
Giovanna Imperia, USA www.giovannaimperia.com
Wendy has been weaving since 2000 and completed the Bradford Certificate in 2003. At that time she joined Complex Weavers, an international organisation for weavers who like to explore the whys and what-ifs of weaving and to share what they discover with other members. Some technical details of this research have been published in the Complex Weavers Journal. Wendy is immediate Past President of Complex Weavers and the owner of the Handweavers Studio.
This article appears in edition #244 of the Journal for Weavers, Spinners and Dyers.
The Journal is published on behalf of the Association of Guilds of Spinners Weavers and Dyers. It covers a wide range of textile subjects, including articles on historic textile techniques and cutting edge modern design.