Fiber & Its Properties

The Craft / Fiber Types

Every fiber is a record of something. Wool holds the lanolin that protected a living animal from wet and cold; silk is a thread that a silkworm secreted to make itself a tomb; linen carries the cellular structure of a plant stem that grew in stony soil. Before the fiber becomes yarn and before the yarn becomes anything else, it already has a nature. That nature affects how it behaves in the dye pot, how it behaves on the needles, and how it holds whatever intention you've set into it.

Understanding fiber types isn't just practical knowledge, though the practical knowledge is useful too. It's understanding what you're working with at the material level, which is where all craft begins.

Wool

Wool is the most forgiving fiber and the one most associated with hand-dyeing, for good reason. The protein structure of wool fiber (keratin, the same protein in your hair and nails) bonds readily with acid dyes and accepts natural dyes with mordanting. The microscopic scales along each wool fiber shaft open with heat, allowing dye to penetrate into the cortex, and close again as the fiber cools. The result is color that lives inside the fiber rather than coating it.

Wool's elasticity comes from its naturally crimped structure. When you stretch a wool fiber, the crimp unfurls; when you release it, it springs back. This is what gives woolen yarn its memory, its bounce, and its tendency to return to shape after blocking.

Different breeds of sheep produce wool with very different characteristics:

Merino is the most widely used wool in hand-dyed yarn, for several reasons. The fiber diameter is fine (15-24 microns), which means it's soft against skin and suitable for garments worn close to the body. Merino takes dye with exceptional saturation and tends to produce the clearest, truest colors of the common wool types. The tradeoff is that fine merino is also more fragile than coarser breeds; it can pill with abrasion and felt more readily with heat and agitation.

Bluefaced Leicester (BFL) produces a longer, silkier fiber with a distinctive luster that merino lacks. BFL is a longwool breed, and longwool fiber has a more open, less tightly crimped structure than fine wools. The result is yarn with drape and sheen, beautiful for lace and for colorwork where you want the stitches to read clearly. It takes dye a little differently than merino, often producing deeper, richer tones with more apparent depth.

Polwarth sits between merino and BFL in character: fine, soft, and with a small amount of luster that gives it subtle depth. Polwarth has a slightly longer staple than merino, which makes it a bit more durable, and it has a particular quality in the finished fabric that's difficult to describe, a kind of quiet luminosity that makes it a favored single-skein colorway canvas.

Superwash wool has been treated to remove or coat the scales that would otherwise cause felting. Superwash is practical (machine washable, care-friendly) but the treatment changes the fiber's behavior in small ways: it can be slightly more relaxed in structure, take dye a little differently, and block to a finished state that's slightly different from untreated wool. Whether superwash or non-superwash is right depends on the project and the knitter.

Silk

Silk comes from the cocoon of the Bombyx mori silkworm, a fiber that is more than just beautiful: it is a record of transformation, of a creature becoming something other than it was. The fiber is a continuous filament, sometimes hundreds of meters long from a single cocoon, and its triangular cross-section is what produces silk's characteristic sheen. Light enters the fiber at one face and bounces internally before emerging, creating the optical effect of glow from within.

Silk takes acid dyes very differently than wool. Because it lacks the scale structure of wool fiber, dye sits more on the surface of silk than inside it, which produces intense saturation but can mean slightly less depth. In blended yarn (merino/silk is a common combination), the silk catches light in a way that makes the overall colorway read more luminous. It also adds drape and a slight coolness to the hand.

Silk is traditionally associated with liminality and with protective magic in multiple folk traditions. In Chinese folk practice, red silk thread is tied around the wrists of newborns and used in protective charms. In West African tradition, fine woven cloth of silk or analogous fiber marks ceremonial transitions. When you work with silk, you are working with something that has always, across cultures, signaled that a threshold is being crossed.

Nylon

Nylon is a synthetic fiber (polyamide) most commonly found in sock yarns as a minority percentage, usually 20-30%. It adds durability to what would otherwise be a fragile all-wool sock. The heel of a sock suffers more abrasion than almost any other point in knitting, and all-wool heels wear through quickly; nylon extends the life of the work considerably.

In the dye pot, nylon behaves oddly. Standard acid dyes don't bond to nylon the way they bond to wool and silk. Some nylons will take on some color from an acid dye bath through a different mechanism; others remain nearly undyed. The result in hand-dyed sock yarn can be a speckle or muted background that reads as part of the colorway, or it can look like a discordant resistance. An experienced hand-dyer accounts for how the nylon in a specific base yarn responds to their dye palette.

Plant Fibers

Linen (flax) and cotton are cellulose fibers rather than protein fibers. They don't bond with acid dyes at all, and require fiber reactive dyes or significant modification to take most natural dyes. This makes them unusual choices for the kind of hand-dyeing described on The Dye Pot, but they have their own properties worth understanding. Linen is extraordinarily durable, improves with washing, and has a quality of accumulating a patina over time. It doesn't have elasticity, which makes it appropriate for certain projects (dishcloths, market bags, some structured garments) and completely wrong for others (socks, fitted bodies). Cotton is similar but slightly softer and with more horizontal give.

In fiber magic traditions, plant fibers generally carry earth associations: stability, groundedness, longevity. A protective charm made of linen thread is working with material that has been used in burial shrouds, sail cloth, and book bindings. It carries the long work of civilization. See the Material Correspondences page for more on elemental associations by fiber type.

A Note on Blends

Most hand-dyed yarn is not a single fiber but a blend. Merino/nylon for durability. Merino/silk for sheen. BFL/silk for drape and luster. Merino/silk/yak, merino/cashmere, various combinations chasing a particular balance of qualities. When you're reading a colorway description, the base fiber matters as much as the dye: the same color on a merino/silk base will look different than the same color on a BFL base, because the fiber's optical qualities affect how color reads to the eye.

The magical properties of a blended yarn are, if you're inclined to think this way, a conversation between the properties of its components. Wool's protective warmth, silk's liminality, the longevity of plant fiber. What you make determines what combination of properties the finished object carries.

Continue reading: The Dye Pot · Working with Hand-Dyed Yarn · Material Correspondences