Friday, August 18, 2006

Fiber 101 continued

And now for the promised second installment. Thank you all for your kind words - you're generally a much more appreciative audience than my family or the engineers and physicists for whom I work!

We covered protein fibers last time - basically anything that originated with an animal or insect. I'll talk about cellulose next, and give some very basic information on the man-made fibers. These are springing up so fast that details are out of date before you can publish them - even on the web! I do think it's interesting that so many of them are attempts to imitate silk. As a confirmed silk addict, I've yet to see any of the synthetic fibers completely measure up to the original, but rayon, soy, ingeo and tencel all have their good points. Interestingly, silk is usually less expensive to spinners than many of these imitations!

I close with some things that I think about when beginning a new project. Take a look, see what you think, and let me know what you think yourself!

Cellulose Fibers

Cotton lint is the surrounding material for the seeds of the cotton plant. Cotton comes in hundreds of varieties and dozens of natural colors. There are many varieties available worldwide. It is a fine-diameter cellulose fiber that is fairly short, with individual fibers ranging from ½ inch to 2 ¼ inches in length. The longer Pima, Egyptian and Sea Island fibers are the luxury standard for cotton. Most of the cotton grown for household uses in the United States is Acala, a short-staple, fine, shiny fiber with little natural wax.

Cotton requires a long, hot growing season with plentiful rainfall. It is also quite hard on the soil; cotton fields should be rotated with nitrogen-rich crops in a minimum one year of cotton and three years of legume or alfalfa ratio. These requirements make cotton a tropic or sub-tropic plant. Cotton can be grown in East Tennessee, but you’ll only harvest about one year out of four – the other years frost will get the crop. (It's also illegal at this point to plant cotton in East Tennessee - we're in a buffer zone for the boll weevil.)

These growing requirements made cotton a ‘luxury’ fiber until the invention of the cotton gin in the late eighteenth century. It’s hard to believe that this staple of our day-to-day clothing was ever more expensive than wool or linen, but until the late 1700’s this was so. The cotton gin and mechanized spinning, however, made cotton fiber and yarn much more affordable.

The labor-intensive cotton agriculture business was one of the main economic justifications for slavery in both the pre-civil-war United States and other countries. Until after World War II all cotton had to be harvested by hand. It is still harvested by hand in much of the world. Having grown a dozen cotton plants each of the past three years (with no crop to show for it yet), I can testify that the idea of acres of these plants is much more work than I want to try!

Cotton can be spun into singles of thicknesses ranging from finer than a human hair to fingering-weight. It is usually spun rather fine and plied to the desired diameter, since larger-diameter cotton yarns tend to wear badly – they get quite fuzzy very quickly. Cotton wicks moisture away from the skin, making it an ideal fiber choice for hot climates and seasons, and the very fine yarns can be woven or knitted into gauzy fabrics that are quite comfortable even in hot, humid weather.

Cotton is heavier than the same yardage of most wool yarns (wool as in sheep’s wool). This means that it should be knitted or crocheted at a tighter gauge, with a smaller needle, than a comparable-diameter wool yarn. This will avoid having the fabric stretch from its own weight. Gravity can’t be fought, but you can compensate for its effects! Cotton has no crimp, and so little or no stretch. This means no recovery with washing, and the necessity for making all the stretch necessary for a garment a part of the fabric structure. Mixtures of cotton and man-made fibers have a little more stretch, but aren’t as cool to wear. Wonderful yarns are made from cotton and silk in combination, but this yarn also needs to be swatched carefully and mindfully.

As knitters, you may find cotton rather harder on the hands than wool, especially if you have a touch of arthritis. The lack of stretch means that you’ll need smaller needles than those needed for comparable weight sheep’s wool. And a non-stretchy fiber makes forming the stitches slightly more difficult. But cotton can’t be beat for summer sweaters and shawls, or light baby clothes!

Most cotton yarns can be machine washed and tumble-dried quite successfully. There are some exceptions out there, though, so check the yarn label carefully!

Flax/Linen, Hemp and Nettle

All three of these are bast fibers, with similar properties and identical methods of production. The fibers are retted from the plant stems in a long, labor-intensive process. Flax is the name of the plant from which linen thread is derived. Hemp and nettle are becoming more common, but are still not yarns you’ll find at the usual local hobby or big-box shop.

These are the longest of the natural fibers except for silk. Individual fibers range from the very fine fibers of plants grown in rich soil to very coarse fibers from plants grown in poor soils. Linen especially is easy to grow in almost any region. Many people plant flax in gardens just for the lovely blue flowers, and don’t even know that they have a good source of fiber along with the flowers.

All three fibers are processed in the same way. I’ve grown flax several times and obtained wonderful fiber, but I live on river-bottom land. Seeds are sown thickly in a well-tilled plot in mid-spring. A fence is frequently put around a flax patch to keep the plants upright, and chicken-wire or a string grid mounted up the fence and across the patch at vertical intervals of 6-12 inches. The tall plants will grow through the interstices and stay relatively straight. The chicken-wire also serves to slightly discourage rabbits.

After the plants have flowered and seed pods formed, they’re pulled from the ground and laid out to dry in the sunshine. After drying, the stalks are carefully threshed to glean the seeds. Then the stalks are either stored until spring or retted immediately.

Retting involves rotting the woody part of the stems to loosen them from the fibers. I fill a large tub with water and sink the stalks, weighting them just enough to keep them under the water level. Water is changed every couple of days. It normally takes about 2 weeks to rot the woody stems sufficiently to be able to pull fiber loose. The stems are removed from the water at that point and again dried out.

The retted and dried stems are broken loose from the fibers with a flax brake or a wooden scutch and sword. Then a handful of stems at a time are combed through successively finer hackling combs until you have the longest, finest fibers. These are spun for line linen. The waste – short or broken fibers – is used to spin tow.

All bast fibers have several things in common. The top-quality yarn of each type will be very smooth and strong. The tow yarns will be very hairy and prickly, much like burlap sacking. The yarns have good body, but no stretch – all the ‘give’ in the fabric must come from its construction. The good news is that knitted bast fabrics don’t crease and wrinkle as much as their woven cousins. All three fibers are cool, wicking moisture away from the body and drying quickly. Linen, especially, is quite absorbent, able to retain more than four times its weight in liquid.

Nettle is absolutely the finest of the bast fibers, but is also the most costly. It is difficult to grow, difficult to process, and large amounts of plant materials are required to make a small amount of yarn. It is, however, almost as shiny as silk and quite fine in diameter. It is the supplest of the bast fibers as well, and the drape of a nettle fabric will be similar to silk.

Linen is next, with the best linen fibers rivaling nettle for fineness. It is somewhat easier to process (you don’t have to deal with the nettles). Linen comes in many grades, and you’ll want to shop carefully. Dye lots are especially important with linen threads, since not only the individual dye-pots but the crops themselves vary so much in color from year to year.

Hemp is becoming more and more popular. It isn’t as costly as either of the other two, probably because it is the easiest of the three to process. Don’t make the mistake of thinking all hemp is like that used for teenagers’ beaded bracelets. High-quality hemp yarns are smooth, supple and shiny, almost identical to line linen of the same weight.

All bast fiber yarns should be knit only after careful swatching. Linen is lighter than cotton, but still heavier than wool yarns of similar grist. Stitches and fabrics will stretch while wearing. However, linen (or any bast fiber) is especially suited for summer sweaters, fine laces, and household items. Knitting is similar to cotton, with the accompanying caveats about the possible difficulties on the hands magnified, since bast fibers tend to be rather stiff until washed a few times.

Care is simple, and similar to other knitted items. Bast fabrics should be either hand or machine washed in warm water, spun quickly to remove excess water (or rolled in a towel), and laid flat to dry. Lace items should be blocked quite severely. These are the only knitted fabrics that will benefit from ironing. Hard pressing with lots of steam should be a part of the finishing for any bast fabric. And that same sort of pressing will revitalize many older linen fabrics.

Bast fibers are some of the longest-lasting fibers. There are examples of linen and hemp fabrics in many museum collections; some are dated as among the oldest textiles found to date.

General notes on cellulose fibers

All plant fibers are much more difficult to dye than protein fibers. Scouring with harsh chemicals so that dye can penetrate the fiber shaft is necessary. Cotton is the easiest fiber to dye in a home setting. I suggest Rit dye for experimentation, and Procyon-brand substantive dyes for intensive exploration. But dyeing large amounts of these fibers takes dedicated equipment and a certain amount of care. I recommend Google and your local library for additional information.

Man-Made Fibers

There are two main classifications of man-made fibers – those made from petroleum-based chemical products and those made from various recycled or waste agriculture products. There are many new and exciting fibers in the second category, but the most common fibers right now are those in the first category. Let’s take a look at them first.

Petro-chemical fibers

Nylon and polyester and acrylics (the oldest polyamides) are the first of these that come to mind, since they’ve been around the longest. The various microfibers are newer versions. These fibers are all created by dissolving petro-chemicals or their derivates in a specific mixture and then forcing the liquid through spinnerets under high pressure. The liquids are extruded into jets of air that dry the resulting fibers quickly, and are then spun in a similar fashion to fine cotton. The currently-popular microfibers are produced in this way, but the individual fibers are much smaller in diameter than those of 1960’s polyester.

These fibers have several things in common. They’re easy-care, machine-washable and dryable, sturdy and don’t wrinkle. They’re stretchy. The older ones don’t transfer heat and moisture well, so they’re hot to wear, but the newer polyamides are more breathable, and indeed have been engineered to imitate natural fiber properties as much as possible. This has improved wearing comfort. In order to enhance their wearability, or add easy-cleaning properties to natural fibers, the two are frequently blended. You will see many microfiber or polyamide blends with wool, cashmere, angora, mohair and cotton. These are normally quite successful from a knitter’s or crocheter’s standpoint, since they offer washability and improved wear while retaining the luxurious feel of the natural fiber.

Superwash sheep’s wool is now most commonly created by coating the individual wool fibers with a polyamide. While this increases the diameter of the wool fiber slightly, it does provide machine-washing capability. You should be careful not to tumble superwash wools on high heat, however, since the coating isn’t always as heat-proof as you might wish.

Care for polyamides is normally listed as easy; machine wash in warm water and tumble dry on low or medium heat. Caution is advised with ironing or high heat, as it can melt these fabrics! You might also want to think twice and check the label for flame resistance before using them for infant’s wear.

Recycled fibers

These are the exciting new fibers I talked about earlier. They range from ecospun, which is basically recycled soda bottles, to soy silk and ingeo, both of which are made from the waste products of soy and corn plants. More are available all the time – one of the latest is made from bamboo fibers and is a good substitute for linen, but with more of a cotton feel.

Ecospun could just as well have gone in the petro-chemical category. It is the name given to fibers made from recycled plastic bottles. Some is shredded quite fine and blended with natural fibers to add washability and extend their wear. Some is simply reprocessed into one of the extruded fibers discussed above. I've had good luck adding this to wool for socks - it increases wear almost as well as nylon.

Tencel is one of the newer fibers made from petrochemicals. It has been engineered for breathability and excellent wear. The feel is rather like silk or supple suede, but Tencel has more stretch and less tensile strength than silk. It is an acceptable substitute for silk, though, and costs less. It is also a good choice for brushed fabrics like ultrasuede.

Soy silk and ingeo are both made from processing byproducts or waste. Technically both are cellulose fibers. They have the shine and smoothness you expect from silk, but should be dyed with cellulose dyes for the best color. These fibers are showing up more and more frequently on yarn shelves. I have spun both, and find the fibers very similar to silk in hand and behavior. They breathe better than most synthetic fibers, and can develop a lovely slight halo with wear that feels rather like suede.

Care labels on yarns should be checked carefully – some of these yarns are machine-wash and tumble dry, some require hand-washing. Tencel, soy silk and ingeo all block well, with only a slight tendency to stretch while wearing.

Choices are yours

Fiber choices abound. Knowing as much as possible about the characteristics of the various possibilities can help you choose the best possible yarn for your project. What follows is a short quiz that might help when you’re assessing the fibers and yarns for a new knitting or crochet project. I go through this almost automatically, and it has never let me down - when I've answered the questions honestly rather than getting carried away!

1. What are you making?
2. Where and how will it be used?
3. What care requirements do you have?
4. How much wear will the item receive?
5. Is this to be a classic part of your wardrobe or a currently-stylish accessory?

Once these questions are answered, you have a starting point. The next questions might be along these lines:

6. How much do you have or want to spend on yarn?
7. How do you want the finished fabric to feel?
8. How do you want the finished fabric to look?
9. How much time are you willing to spend?

Only then should you look at things like color and design. We’ll discuss a couple of possibilities to give you a feel for how your thought processes might go on a project.

Project 1: I want to make a purse for a young friend. She’s very stylish, loves vintage fabrics and is likely to wear classic, well-tailored clothes. She is currently a college student, but will graduate soon and enter the job market as a professional. All right, let’s take a stab at the questions.

I’m making a purse. It will be lined. It needs to be sturdy so that it can be carried, with a long handle – preferably one whose length can be adjusted in some fashion. It should stand up to rather heavy wear, but is probably not going to be used for more than a couple of seasons. Being able to wash it in the machine would be a plus, but isn’t absolutely necessary.

At this point I’m looking at several possibilities. Cotton, linen, hemp and wool would all wear well, and all are at least hand-washable. Felted wool would be quite sturdy and water-resistant as well. You could brush it clean, and the colors are great. Cotton would also be nice, and comes in bright colors. I’d need to choose a lining carefully and knit on small needles, though – I’d also have to allow for stretching. Hmmm, I’m leaning toward wool, but let’s keep going. Linen and hemp would work well, but are harder to clean and knit than wool and cotton.

I don’t want to spend a great deal on this, either in money or in time. That pretty much lets out linen and hemp, both of which are more expensive choices than cotton and wool. I’d like the finished fabric to be touchable, something you enjoy tucking under your arm. It should look classic, even somewhat elegant. Cotton tends to look beat-up and old more quickly than wool.

All right, I want a worsted-weight or bulky wool in classic colors – plum, burgundy, cream, dark green or black. I’ll knit the bag and then felt it, and line it with some vintage upholstery silk I have in my stash. Straps can be knitted I-cord, felted at the same time as the body of the purse and then sewed on with the lining. It will take about $25 in materials (if I don’t have anything I need in my stash already) and a maximum of a week of knitting time, with an extra evening of finishing and sewing.

That wasn’t so hard! Now let’s try something a little more challenging for Project 2.

I need a sweater to wear for work. It will need to go with my usual gray, black, tan and brown slacks – preferably with any of them – and be wearable in at least three seasons.

For three-season wear I can use cotton, silk, linen, or light-weight wool. Alpaca and cashmere blends might be a little warm for spring and fall, though they would feel wonderful. It needs to be relatively easy-care, either machine washable or easily hand-washable – no dry-cleaning. It will get quite a bit of wear, since my work clothes tend to be worn about once a week. So wear points like underarms and necklines should be abrasion-resistant. That pretty much lets out silk, which abrades quickly. I don’t want to spend the money for 9 or 10 skeins of line linen, even though it would work well for the project, and I don't particularly want to knit linen. It needs to look somewhat dressy – nice business attire for wearing on those days when I have meetings with folks from outside my own groups. But I want a touchable, comfortable fabric.

Either wool or cotton will work for this. If I choose wool, it should be in no more than a fingering-weight yarn, and lace-weight would be better, with multiple tightly-spun plies to resist abrasion. Short sleeves would be best; ¾ sleeves are acceptable. Cotton would also work well, but I’d need to allow for the stretch from the extra weight of a cotton yarn. Let’s shop for this with an open mind. Look at the sale bins first, and then go on to the shelves. This will be a classic, and I’ll wear it for several years, so I can afford to spend a bit more time on it. A natural or pastel color in the red or blue-green color families will work best with my usual dark slacks.

Are you beginning to see how it works? Let’s try one last project, simply because it’s something you’ll do sooner or later. You need a gift for a new baby. This one should be really special (for your own child or grandchild). You want to do something that will be used for the first year or so, but only on special occasions. However, since babies are basically messy creatures, you need to allow for that. Let’s say you decide on a baby blanket in a lace stitch with a lace border (I did say it was special). Your choices are many. Wool is classic, and can be bought as superwash to make care easier. Cotton may be a good choice for a baby in the South or Southwest, and is probably the easiest-care choice. Silk is also a possibility, either alone or mixed with either wool or cotton. It gives a drape and shine you won’t get with either fiber alone, and can be a little bit warmer than cotton alone. You don’t want to use a fuzzy mohair or angora, even in the wintry Northeast, since those fibers tend to make babies sneeze. Tencel is also possible.

This is going to be a lace structure, so the thread should be firmly spun and a minimum of two plies in order to show the pattern to best advantage. Smaller needles will be required to make sure baby fingers don’t get caught, so it will take a bit of time to knit.

Surprise! You can use cotton, wool or silk, tencel or a blend of any of these. If the mother won’t take proper care of fine sheep's wool, use superwash merino or a superwash/silk blend. Be sure you get something whose label says it’s machine-dryable! Cotton can be bleached to get rid of any particularly messy stains. Silk can’t be bleached, but a solution of peroxide and water will do a great job of whitening stained areas.

Traditionally, natural white/cream is used for this type of thing, but you can suit yourself. Generally speaking green and yellow are not the best choices for very young children – they make them look slightly jaundiced. Lavender, blue, pink or even brighter colors like red and royal blue are better choices for colored yarns.

Now that you have a good general knowledge of how each fiber will behave in a yarn, you can experiment with more confidence. By all means make choices ‘outside the box’. But do it knowing what allowances will have to be made for those choices! And have fun along the way!


Zippianna said...

Pamela, your site is awesome! Thanks for posting all the information on fibers. Wow!

Erica Lueder said...

I just wanted to say thank you for all of the information that can be found on your site - I have been going through some of your archives in my spare time. I am very new to spinning so any information is greatly appreciated. Thank you again.
Erica Lueder

Lina said...

What wonderful information! I had a question though:

how do you know the different grades when you are shopping around for linen? I live in Egypt and the shops overflow with linen but I really can't tell what is top of the line. Any tips to keep in mind when shopping? Thanks!

Anonymous said...

This is a great article, and you have a lovely blog that has a lot of useful information.

Thank you for your trouble!