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!


Katherine said...

What great information! It is sad that most people have no clue about this stuff anymore. My family was weavers in Sweden, so I feel like I have fiber in my blood. My mom is a fiber nut so she raised me right. I remember learning at an early age that natural fibers were best, and different ways to tell fabric types apart. We would do burn tests on little scraps, and rather than telling me "don't touch!" at the fabric or department store, my mom would have me feel the fabrics and try to identify them.

Of course, all this didn't stop me from accidentally shrinking a wool sweater my first year of college, though :). The young are prone to mistakes, I guess!

By the way, your advice on spinning soy silk was very helpful and I have finally gotten underway on my project. There are some pictures on my blog, if you'd like to take a look. I am discovering the joys of spinning laceweight!

Sner said...

I've got to say that everytime I see your blog has new content I say a not so silent YES! I so appreciate your knowledge and your willingness to share it. I am a beginning spinner and would love to eventually reel my own silk. I'm going to try in the new few days to make some silk hankies from cocoons I bought at my LYS. It should be exciting! Thanks again for providing information you just don't see elsewhere.

Joanna said...

Thanks for all this wondeful information. I have a Clothing and Textiles Major and know most of this ( or did years ago) but the information more relevant to spinning was not exciting then, but certainly is now. I am trying to get a "feel" for spinning the different types of merino now, but have yet to add any of the specialty breeds or silk to my fiber sources. Your information is very easy to understand, and I thank you for the time it takes to do this.

I just got my own carders, so look forward to the carding and combing instructions!

Erica Lueder said...

I just wanted to say thank you for providing such wonderful information on your blog. I am a VERY new spinner so any information is greatly appreciated. Thank you again!
Erica Lueder

elizabeth said...

I have to say, once again, how much I have learned from your blog! I am so happy that it's still up and I point new spinners to it frequently. Are you on Ravelry? I'd like to friend you! My Rav id is "flwrhead", if you get this and feel like replying.