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 These are springing up so fast that details are out of date before you can publish them - even on the web!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!

Saturday, August 12, 2006

Fiber 101

This is something of a new adventure for me. I’ve been teaching fiber-arts for quite a while now, and rather than have my ramblings pieced out all over the blog, I’ve decided to post some of my more formal class materials here, in sections.

I was talking to my son earlier this week. We’d been on a dorm-furnishing shopping spree, and run into some folks in the store who were doing the same thing. Since the other college-bound student was a pretty girl, my teenaged son was happy to strike up a conversation. That conversation sparked the comments outlined below.

He was astonished at the lack of general knowledge his fellow freshman showed about what she was buying. She knew nothing about thread counts on sheets and towels, why cotton would be the best choice for most of those items, and had no clue that flannel sheets might be uncomfortable between August and October, March and May in East Tennessee. Or that jersey or silk sheets might be downright cold during our rainy, humid winters. “How can she not know this stuff, Mom?” he asked. “She’s bright – she’s a physics major – so how can she be so dumb about the little stuff?”

I had the unenviable task of explaining to my deluded offspring that many people weren’t raised with fiber artists as one parent and one grandparent, didn’t have a spinning wheel or loom in every public and most private rooms of their family home, and hadn’t learned spinning, weaving, crochet, tatting and knitting as a child. This basic knowledge regarding fibers was part of his childhood education. Since he was a gregarious child with a wide circle of friends, they also picked up much of this knowledge from either him or from me. But the majority of teenagers don’t have a clue – and guess what? Most adults don’t, either!

My new students frequently lack this basic knowledge base. It is no longer part of our cultural heritage, and if you don’t go looking for the information, you may very well be the sort of shopper who never really thinks about why wool is sold in the winter and cotton in the summer. Bur for those who are now curious, I’ll begin a tutorial about the basics – call it Fiber 101.

Fiber 101

Let’s talk about the raw stuff of fabric, whether that fabric be woven, knitted, crocheted or felted. At public demonstrations I often comment that “everything starts with the yarn.” That’s absolutely true. And a good understanding of how a yarn is made, and from what, will let you know the best fiber to choose and how to care for the article made from the resulting yarn.

First, let’s define some terms:
Fiber is the raw stuff – straight from the animal or plant.
Yarn is the spun fiber; the difference is in the added twist from the spinning process. That twist gives the needed friction to extend short fibers into long yarn.
A textile is the finished fabric, either knitted or crocheted to shape or as knitted, crocheted or woven yardage to be cut and sewn.

Fibers fall into two main categories – natural and man-made. There are some exciting new fibers that are probably best categorized as recycled, and we’ll talk about those later. The vast majority of our clothing and household textiles are still made from either cotton, wool, linen or silk or some combination of these with a man-made fiber. Where do these natural fibers come from and why are they chosen for a particular fabric? We’ll explore the differences and choices.

Within the two main categories of natural and man-made fibers are sub-categories. Natural fibers have two sub-categories – protein fibers and cellulose fibers. Generally speaking, protein fibers come from animals and cellulose fibers from plants. Man-made fibers also have two main sub-categories – petroleum derivatives and recycled fibers. We’ll discuss both, starting with the protein fibers because they have such a wide range of possibilities and challenges for the fiber artist.

Protein Fibers

Let’s talk about wool first. Wool is, in broad, a generic term for the outer body covering of any quadruped. These coverings are primarily constructed of protein arranged in a linear fashion - hair. In general conversation wool means the outer covering of a sheep. But in a broader sense wool can mean part or all of the outer covering of a sheep, llama, alpaca, rabbit, dog, cat, cow, horse, goat, musk ox, bison, yak or New Zealand possum, among others. You can find yarns from any of those animals except cats and dogs in any well-stocked yarn store. Each type of outer covering has different end uses, usually dependent on the fineness and length of the individual fiber. As a general rule, most of the animals listed above are raised only partly for their fiber, which is harvested each year by shearing or rooing (plucking or combing). With the exception of the New Zealand possums, which are terrible imported pests in that habitat, and buffalo or bison, which are being raised for meat, animals are not generally slaughtered for their fibers.

Wool is further divided into fleece and down. Fleece is usually the outer coat, but in breeds where the outer coat is quite coarse (horse, bison and cow), it can also be the term used for an inner coat. In general, fleece contains fibers from 2-8 inches in length and is of varying diameter, which can be measured on either the Bradford scale (mostly used for sheep’s wool) or in microns. Down is always an undercoat, and generally consists of fibers that are quite short – ¼ to ¾ inches in length – and fine, with diameter commonly measured in microns.

Fleece runs the gamut from rough and hard-wearing (think rugs and seaman’s sweaters and upholstery) to soft and fragile (think soft kid mohair or angora sweaters and fine-wool baby layettes). Insulating properties are good, and can be modified easily by spinning the fibers in either an unaligned or aligned fashion.

Unaligned fibers are used for woolen yarns. In general woolen yarns are not as long-wearing, but are very warm. The tangled fibers trap body heat and hold it within the spaces between fibers. Aligned fibers are termed worsted yarns, and are usually smoother, harder and longer-wearing than woolen yarns. They can be more easily worn in a wide range of temperatures, since the closely-aligned and compacted fibers allow heat to dissipate more easily.

There are a couple of other characteristics of fleece that can be exploited to create specific textiles. Fulled or felted fabric can be created by the application of any two of the following: heat, soapy water or agitation/abrasion/pressure. Fulling and felting will cause fibers to lock more tightly together, creating thicker, sturdier, less elastic fabrics. The process will also shrink the dimensions of the original textile. Some fleeces felt easily. Fine-wool sheep, alpaca, mohair goat and angora rabbit come immediately to mind. Simple wear can felt these fibers. Some fleeces are more difficult to felt; down-breed or long-wool sheep, Highland cattle, horsehair, and llama are examples.

Sheep’s wool is naturally flame-retardant. This makes it an excellent choice for items that will be worn in a camping environment, and anywhere you’ll be around a flame. Fine sheep’s wool is also a good choice for baby wear, since it’s a natural insulator, comfortable in all but the very warmest weather. Sheep’s wool has another interesting characteristic that makes it especially good for cold, wet weather. It will retain heat even when wet. This is what makes wool an especially good choice for wearables like socks, gloves and hats.

Down is normally the inner coat of an animal, although the term is sometimes used (in error) to describe short, very fine plant fibers like those from cat-tail and nettle. Down is usually very warm and not particularly strong unless plied. The fibers are generally too short to spin in anything but a woolen fashion – worsted 100% down yarns are a practical contradiction in terms except for hand spinners. Individual fibers are largely hollow, which accounts for their warmth. Unlike fleece, which is mostly (though there are exceptions) harvested by shearing, down is normally harvested by rooing or combing the short fibers from the coat. Most animals’ down is harvested from live animals, but this isn’t always safe. Bison, yak and buffalo down is either gathered from their environment or harvested from animals slaughtered for meat.

Some downs will felt; some will not. These differences appear to have more to do with individual animals than with breed differences. Downs have a low resistance to abrasion and usually become quite fuzzy with wear. This characteristic can be enhanced or modified by blending down with other fibers.

Fleece and down can be cleaned in the same way. A 10-minute soak in hot soapy water followed by two or more rinses in water of the same temperature will clean these fibers nicely. You may want to add a splash of white vinegar to sheep’s wool fabrics to restore the pH to a more normal level. Wools should be laid flat or blocked to air-dry. The heat and tumbling action of an automatic dryer provide the two necessary components for felting. Remember that sheep’s wool sweater you accidentally threw into the washer and then the dryer?

Bradford Scale for Sheep Wool

Type of Wool

Extrafine merino
Superfine merino
Fine merino
Standard merino
Medium wool
Coarse wool
Braid (very coarse) wool

Spinning Count


Micron Count

over 40


Silk is the other protein fiber. Silk is the continuous filament extruded by bombyx mori to form the cocoon in which the larvae transforms into the adult moth. Various elementary and middle-school children have described this as gross; I find it quite fascinating. Bombyx mori are native to all continents, and their favorite food is mulberry leaves. However, the species must survive, and so the larvae will feed on almost any available foliage. The type of foliage determines the color of the cocoon, and the strength of the fiber extruded for that cocoon. Mulberry leaves make for the whitest, finest cultivated silk fiber.

Silk cocoons are gathered and a tithe is reserved to hatch and mate for the next cycle. The other 90% of the cocoons are either baked, heated in a large skillet or plunged into boiling water briefly to kill the larva and prevent hatching. The emerging moth creates holes and tears in the cocoons which break the continuous silk filament, making the cocoons useless for high-end applications. However, wonderfully textured yarns are spun from the hatched cocoons.

Silk cocoons are reeled for the strongest, shiniest yarns. I’ve reeled silk a few times, and you may enjoy a brief description of the process. After breakfast I put very hot water into a crock pot and turn it on low. You want the water to remain just below a simmer in order to dissolve the sericin (the glue extruded by the silkworms that make the fibers stick together). Boiling water will explode the fragile silk filament. Chuck in 30-45 cocoons (about an ounce) for an afternoon’s reeling. After a couple of hours, when the cocoons have begun to soften and get mushy, I place the crock-pot on the kitchen counter just beneath the cabinet. I next suspend a canning jar ring or macramé ring above the top of the pot as a guide. Stirring with a chopstick or toothbrush will start the filaments unraveling from their cocoons, and you’ll guide anywhere from a dozen to 20 filaments through the canning ring guide. They’ll stick together nicely – the sericin is still on them – and look like a very narrow ribbon. Now you need some space, because you want those filaments to have a chance to dry before they’re wound onto the reel. I have a long, narrow kitchen with the dining room at one end. So I put the crock-pot at the far end of the kitchen and fasten the reel to the dining room table. That gives about 20 feet, which is plenty of space for the drying.

Once the setup is complete I carefully and slowly crank the reel, pulling and basically unrolling the filaments from those 12-20 cocoons until I reach the point where filaments are breaking. Then I join in more cocoons from the crock-pot. By the time I’ve reeled all the cocoons, it’s time to start supper and I have about 10,000 to 15,000 feet of rather crunchy, very thin and fragile silk ‘ribbon’. I carefully remove the reel from the table and shift it out of the way for the evening. Next day I’ll remount it in the studio, about 5 to 10 feet behind my spinning chair, and spend several hours ‘throwing’ the silk, or adding twist. The extra twist not only enhances the shine, it makes the thread stronger. Then I’ll ply that yarn back on itself two or three times to make a strong, very shiny, very thin yarn for weaving, knitting or needlework.

There are alternative methods of silk preparation, and each alternative makes a very different-appearing yarn. Simply soaking, then drawing out the cocoons and spinning will make a textured yarn with a great deal of shine. Or use the cocoons from hatched moths and the waste bits from the reeling process, cut into short pieces and carded, to make a textured, slubby silk noil yarn.

There are other substitutes that are acceptable food for bombyx mori, although the cocoon fibers spun by these moths will be various shades of tan, gold-brown or brown, depending on the type of leaf and the amount of tannin contained in the leaves. Silk worms fed leaves other than mulberry are used to make tussah silk yarns. The various processes for harvesting are identical, but the individual filaments are normally stronger and thicker than those of mulberry-fed silkworms.

Silk doesn’t felt, and should be washed in the same way as wool fibers unless the dyes used on the yarns are not color-fast. In that case you’ll want to hand wash and rinse in cool water and mild soap, finishing with a splash of vinegar in the final rinse. Hang or lie flat to dry, depending on the weight of the fabric. Silk will stretch in a looped fabric, so make large swatches and hang for a day or so before measuring.

General notes on protein fibers

Protein fibers dye easily with many household colors and a vinegar or citric acid mordant. Dyeing protein fibers is a great deal of fun, and easily done with food colors or unsweetened Kool-aid powder. Additional details and instructions can be found easily by typing “wool dyeing methods” into Google.

Sheep’s wool fibers have various amounts of crimp. This crimp is renewed whenever the wool gets wet, and gives sheep’s wool a good amount of elasticity. For this reason wool is frequently mixed with other fibers that don’t have this type of memory, including other wools like mohair, angora and alpaca, but especially with down and luxury fibers. Since mohair, angora, alpaca and all of the down fibers are also luxury fibers, this can make for more affordable fibers and yarns. While 100% alpaca or kid mohair yarns feel wonderful, they can present problems when used as the only component in sufficient yardage for an entire worsted-weight or bulky sweater. The sweater grows throughout the day’s wearing, and is really too warm to wear except outside on sub-zero days. Mix the luxury fiber with anywhere from 50 to 80% fine sheep’s wool and you have a fabric that is just as soft, much less heavy, and much more wearable than that same fiber alone. And it won’t break the budget! If you must have 100% luxury fibers, plan for the time to make the garment from fine-gauge yarn. The garment will both look better and feel better while you’re wearing it.

Most ‘wool’ yarn that you purchase will be sheep’s wool, and most of that is merino with a Bradford count ranging between 62 and 64. The exception is usually found only in weaving yarns, where you may run across rug wools with Bradford counts in the 30’s and 40’s, and also suiting or tweed yarns with Bradford counts in the upper 40’s and 50’s. Spinners generally learn a great deal more about this end of the sheep’s wool scale, but knitters and crocheters normally deal with one or another grade of merino. Don’t be fooled into thinking that merino is merino is merino. There are at least four distinct grades of merino, and each feels very different. Check out that Bradford scale again for some clues.

Be careful when using ‘superwash’ fibers. Generally, superwash is a treatment given to fine sheep’s wool in order to make it resistant to felting. The individual fibers are either coated with a polyamide or soaked in acid to eliminate the scales that make wool fibers lock together. Superwash treatments will NOT apply to any other fibers that are blended with the wool, however. A friend was heartbroken not long ago because she threw a hat knitted from a superwash wool, silk and kid mohair yarn into the washer and dryer. The superwash wool and the silk didn’t felt, but the kid mohair did! It’s now a very odd-looking hat. And some superwash is machine washable, but not machine dryable. If in doubt, check the label or hand wash!

Superwash wools are sometimes highly recommended for baby items, and can indeed make easy-care and snuggly, warm baby items. Be sure to check the labels for flame-resistance, however. A polyamide bath can sometimes change the normally flame-resistant structure of sheep’s wool. You don’t want to dress a baby in something that could burn them badly!

Next we'll take a look at cellulose fibers - probably next week!