Tuesday 13 May 2008

Yarn calculations

Yesterday I wanted to plan a yarn order. There are two particular projects I have in mind. The first is to weave a twill sample blanket, following instructions in Janet Philip's new book, Designing Woven Fabrics.

This requires 6/2 and 12/2 cotton yarns. Most helpfully she gives weights of yarn required in her book. I am going to alter the colours slightly. The two main colours she uses are white and navy. I have done a lot of samples in white and navy recently, so I have chosen to work in primrose yellow and royal blue instead. This still gives good strong contrast to show the weave patterns.

Project two is a lace weave cloth in mercerised yellow cotton for my sister's dressing table. She has a beautiful Victorian chest, french polished, and is concerned that it might be scratched by the bits and pieces she keeps on top of it. Yellow is far and away her favourite colour, and will go well with the yellow-orange-red colour range of the patchwork quilt I made for her wedding.

For project two, I needed to do calculations to find out how much yarn I need. This is something new for me. I went to Janet Philip's first book, The Weaver's Book of Fabric Design, pub. Batsford in 1983. She gives equations for warp and weft calculations.

The amount of yarn needed for warp is the ends per centimetre x width in centimetres x length in metres x Tex number of the yarn, divided by 1000.

What is the Tex of my yarn? This information is not given by my supplier. I know it is 12/2, what exactly does 12/2 mean, does it help for working out Tex? I found a definition of Tex: the weight in grammes of 1 kilometre of yarn.

This looked like a very difficult task. It took me some time, and plenty of digging around my books and files for information. Along the way I found various bits of information I thought needed keeping together. I started a new folder for yarn information, including things like sett ranges for different yarns, reed sley charts (I found I had 4 different ones!), notes on yarn counts and project planning sheets. It's a bright red folder so hopefully easy to find when I need it.

I discovered that my 12/2 cotton yarn means that the yarn is 2 ply, and the 2 single yarns are both of cotton count 12. This seems to be an imperial measurement. I found in notes from another weaver that the cotton count is the number of hanks of yarn of 840 yards which weigh 1lb.

The yarn count didn't seem to help with Tex. However, then I found notes I made from the SI/Metric website. The purpose of this website is to assist with Standard Imperial to metric conversions. There isn't much on yarns, but I found in my notes I had put information on yards per pound / tex together with an article by Rosemary Brock from her website called "Amount of Twist". The yards per pound of 12/2 cotton - 5040 from SImetric gives a tex of 98 in Rosemary's chart (for which she gives credit to Peter and Jacquie Teal).

I decided to check this against my own yarn. I measured out 10 metres of yarn and weighed it on my scales (which are accurate to 0.01g). The weight was 1.1g. This would be 110g of yarn per kilometre - Tex 110. That's reasonably close to 98, my yarn must be slightly fine for it's count.

So, now I could make the calculations. I just had to convert ends and picks per inch to ends and picks per centimetre. The sample I wove that I want to base the cloth on was at 24 epi. I recalled that an inch is about 2.4cm, so decided to work with 10 ends per centimetre and picks per centimetre.

This was taking a fairly long time to work through, but next time I will know what I'm doing.

I multiplied: 10 ends per centimetre x 46 cm wide x 1.2 c.m. long x Tex 110, divide by 1000. I got 54g. Plus 54g for the weft calculation. Only 128g? I was surprised. Then I started to think about loom waste. I realised that my loom needs 1.5m for loom waste (that's slightly generous) and I want some extra for sample length in case I need to make changes or adjustments before weaving the piece. Say, 2m extra. Well, that about doubles the yarn needed. I got my boyfriend to check all my calculations for me. He did, and then pointed out that weaving on a loom like mine is a production method - it's for producing large amounts of cloth. I'd better think again and weave more than one small piece of cloth! After all, she might need at least two so she can wash one from time to time.

Now I can order some yarn.

Saturday 10 May 2008

Thrown silk - and the Macclesfield Silk Industry

I've been lent a most readable history book, East Cheshire Textile Mills, published in 1993 by the Royal Commission on The Historic Monuments of England, now, sadly, out of print.

I live in the west of Derbyshire, close to the Cheshire border, and one of the mills featured is a watermill only 20 minutes walk from our house. This book brings together places and buildings I know with the story of the local textile industry, hence there is much to interest me.

The textile mills of east Cheshire came about because of water power - the streams and rivers running down from the pennine hills made mill machinery possible, and the first mills were built in the 1700s. The silk industry in this area pre-dates the cotton industry.

Silk throwing pre-dates the mills and was carried out in this area in the 1600s to meet a growing demand for luxury and fancy goods. However, the throwing techniques used were not capable of producing organzine for warp threads and until Italian methods of throwing (using water-powered machinery) were introduced in the early 18th century, only the lower quality tram thread (used for weft) was produced and organzine had to be imported from Italy.

The first mill producing organzine was built in Derby (in Derbyshire, not Cheshire) in 1704, on the banks of the river Derwent . It is thought that this was the first powered mill in England.

It was 1744 when Charles Roe, a button merchant, put up the first silk throwing mill in Macclesfield.

So how was the tram thread produced before mechanisation? There's an amazing account taken from an 1841 Parliamentary enquiry:

"... He (the boy) takes first a rod containing four bobbins of silk from the twister who stands at his 'gate' or wheel, and having fastened the ends, runs to the 'cross' at the extreme end of the room, round which he passess the threads of each bobbin and returns to the 'gate'. He is dispatched on a second expedition of the same kind.... "

The twister's wheel was turned to twist the threads, and the threads then wound onto a bobbin. The room the boy ran up and down was between 25 and 35 yards (23 - 32 metres).

When I read this description, it fixed in my mind a clear understanding of what thrown silk actually is, and how / why it is different to a spun yarn.

The process of producing thrown silk - reeling and winding silk from the cocoon, cleaning and throwing - was inefficient and the waste silk from the process was estimated in 1765 to be around half of all the silk. As silk was so valuable, and as the industry increased, there was a great need to find ways of using this silk.

Here there is a link to the cotton industry (for which nearby Manchester and Lancashire are famous).

Machinery created for cotton spinning was adapted for silk. To begin with, the silk was cut into short staples, 25-50 mm in length, which could be spun on cotton spinning machinery.

Then Gibson and Campbell of Glasgow obtained a patent in 1836 for a machine for the spinning of long staple length silk, up to 250mm length. This enabled production of high quality yarn from the better quality silk filament waste. Silk spinning became established in Cheshire, in mills at Macclesfield and Congleton, by the early 19th century.

Macclesfield, Cheshire had not only mills for production of silk thread, but also was a centre for weaving. During the 18th century there was a thriving handloom industry, with weavers either working independently or as outworkers. For example, in 1818, one silk manufacturer, Henry Critchley, employed 140-160 weavers. 50 worked at his factory premises and the rest were outworkers, weaving in garrets. Garret houses were specially built with the top (third) storey having large windows to make good workshops, and two dwelling floors below. Some of the houses were built in terraces with one long garret above several dwellings. It is easy to spot many of these distinctive houses today.

If you have an opportunity to get there, you will find some excellent museums in Macclesfield.

The publications in the late Ralph Griswold's Online Digital Archive include Silk by H. Gaddum of Macclesfield and Luther Hooper's book, Silk: Its Production and Manufacture which I mentioned in my previous post. Use this link for the publications on silk.

Sunday 4 May 2008

A Fine Book

I have a new book, it is A Fine Fleece: knitting with handspun yarns, by Lisa Lloyd,just published by Potter Craft in the U.S., ISBN 978-0-307-3334683-4. I'd seen a couple of brief reviews of this book and thought that I'd buy it on the basis that if I didn't like it I could probably find another home for it without too much trouble.

It arrived a couple of days ago, from Amazon U.K. (for £12.59 it was the last copy in stock, and now strangely they now suggest it isn't yet printed - weird?) and I'll be keeping it. I like it. It's basically a patterns book. Did I need a patterns book? No, not really. But I think this book is a bit special. It's also about preparing and using handspun yarns and about choice of yarn for a particular design.

The author is an experienced knitter and knitwear designer learnt to spin quite recently. That's just about the opposite to me – I learnt to spin so had to re-learn knitting!

It's not a book about spinning, but she does give her thoughts on spinning the yarns for the projects in this book, and I found it good to read. I love good writing, I adored Shakespeare at school and then studied English Language and Literature at University. Nowadays I find that too many books seem to have been written in a rush, barely edited and don't read well. Lisa Lloyd doesn't use words just for effect, every word has meaning. She has interesting things to say about spinning and knitting and there's an underlying sense of good humour. She seems to love her subject and also love writing about it. She sees herself as a storyteller, punning on the word “yarn”.

This is from her introduction to the book:

After more than thirty years of knitting everything from acrylic to buffalo, I know one thing: It's all about the yarn. And so my storytelling begins.

This is the right book for me at this time because I'm working at understanding yarn and fibre choices for knitting and weaving. I'm also interested in planning better – thinking more about the end purpose before I start spinning.

If you need help with learning to spin, you need to work through an instruction book (or class) first. However, anyone who has mastered the basics of spinning can prepare their own yarn for her patterns as the yarns she uses are basic 2-ply semi-worsted. She uses some blends of fancy fibres for some of the patterns and provides good information on how to blend fibres and on her own fibre choices. One idea I liked was adding a little angelina fibre to fine wool for a lace scarf, giving a delicate sparkle.

Strangely for a pattern book, this book is about breaking rules. It's about how to make choices and decisions for yourself, whether you buy a yarn or spin the yarn you want for a particular project yourself.

"The first rule of knitting is that there are no rules." (p.14)

Each pattern is shown knitted in a handspun yarn and in a commercial yarn, emphasising the freedom to chose. Yarn characteristics are properly described – how much yarn, the weight and length of commercial yarns used so it is easy to make substitutions. She makes it clear that the most important thing – whether you use handspun or commercial yarn - is to knit a swatch not just to check needle size but also to make sure the yarn looks right in the stitch pattern.

"Classic design never goes out of style". (also p.14)

The 26 patterns are traditional in style: cabled sweaters, a couple of lace scarves, a hat, socks, cardigans, jackets and vests (waistcoats). The styling has little contemporary touches and the stitch patterns have a fresh look to me – traditional and yet a bit of originality about them. They look simple, but a bit special at the same time. All the patterns are graded for intermediate beginner, intermediate or experienced knitters and she explains clearly what these categories mean by giving examples of the type of garment you might have knitted before. I'm just about “intermediate” – this is exciting progress, 12 months ago I was definitely “beginner”.

The resources section at the back of the book is very good for book recommendations, but the suppliers listed and commercial yarns are all U.S. If you are in the U.K., and don't spin yourself, then here's a little list of interesting spun yarns for traditional knits offered by small businesses:

UK Alpaca (yarn from fleece of Alpacas farmed in the U.K.)

Garthenor Organic Pure Wool (organic wool yarns from named sheep breeds).

Moondance Wools (spun from natural coloured fleeces from their own multi-coloured flock of Shetland sheep).

Wingham Wool Work (take a look at the Aran weight yarns from British sheep breeds and 5 ply gansey yarns).

For sources of fleece for handspinners in the U.K., and sources of spinning wheels and tutors, see those listed by Chris Jordan at her handspinner's resources page.