Fiber Properties That Can Be Your Friend Or Foe

It always amazes me that you can take two sticks, some yarn and create a fabric. Yes, knitting is one of the categories of fabrics. I’ve discussed fibers and yarn construction in my ebook It’s All About The Yarn.  I want to take a closer look at some often neglected fiber properties that affect your hand knit projects. Fiber properties, yarn construction, and stitch patterns are not independent of each other, but work together to create the project you desire. The properties discussed below aren’t necessarily “bad” or “good”, but are important when choosing yarn and to the overall success of a design.

Elasticity or Resiliency 

Elasticity is the ability of a fiber to return to its original shape after being stretched. This means the fiber is flexible and prevents a fabric from wrinkling. Wool is one of the best examples of this property. Just try squeezing a ball of wool or experience the ease in which it glides across your needles. Wool is by far the favorite of knitters, and mine.

The elbows of sleeves and cuffs are areas of garments that tend to wear out first, but can withstand heavy wear when made with a resilient fiber. Most animal fibers are resilient. Silk and cotton are examples of fibers with low resiliency, and tend to stretch out of shape with wear or use.

The amount of elasticity also affects how a garment drapes or hangs. Because cotton stretches, it is typically unsuitable in designs with allover cables or other dense pattern stitches, adding too much weight. One time I used 100% bamboo in a structured cardigan, a big mistake; it was heavy and draped too much.


Loft describes yarn that is open, springy, and appears bulky in comparison to its weight. Mohair is fluffy and light weight, but appears bulky in texture. Loft is created by the air space between individual fibers, and provides insulation. Wool fiber has a natural crimp producing an open structure that traps heat.

Fibers with high loft also have high elasticity, which prevents the fabric from flattening. If you take a ball of wool or mohair and squeeze, it springs back.


Pilling on the surface of a knit fabric.
Pilling on the surface of a knit fabric.

You’ve probably noticed unattractive, fuzzy balls on the surface of your sweaters. These balls of fiber are called pills, and are the result of short fibers entangling on the surface of the textile, caused by abrasion or friction. Abrasion occurs in areas of heavy wear such as cuffs, inner side of sleeves where the arm rubs against the body, and heels of socks.

All knitted items pill to a certain degree. The degree of pilling is affected by the type of fiber, yarn construction including twist, tightness of the knit fabric, and the pattern stitch. Pills are common with softly spun, single ply yarns. Acrylic and other synthetics pill more than natural fibers. Because synthetic fibers are so strong, the pills don’t break off the surface, whereas pills are easily removed from natural fiber surfaces. Many knitters prefer natural fibers for this reason – an acrylic item can look like “pill central” in no time and you can’t remove them. You might want to stay away from acrylic for projects that require many hours of knitting and complex stitch patterns.


Felting is a textile term describing the shrinkage of animal hair fibers, particularly wool. The cause of felting is due to the fiber’s structure. The wool hair fiber is composed of scales along its surface. When these scales are exposed to heat, moisture, and agitation, they entangle or lock together forming a dense, matted fabric. I’d be willing to bet many of you have accidentally felted a sweater by putting it in the washing machine. Careful attention must be paid when washing animal hair fibers.

Felted fabric is produced by textile manufacturers to make dense fabrics such as boiled wool and melton. Felting projects can be an enjoyable process when done “deliberately”. Superwash wool has been treated to prevent shrinkage, and items are safely laundered in the washing machine. But trying to felt with superwash wool won’t work!

Absorbency And Static Electricity

Static electricity is produced by an accumulation of electrical charge. It is a huge problem with synthetic fibers which lack the ability to absorb moisture. Even natural fibers will exhibit static electricity in low humidity, but is easily reversed. Synthetic fabrics feel hot, pill readily, and hold static charges making them easily soiled and difficult to clean.

Even though you may be dying to use a particular yarn that exhibits any of the above properties, there is a project out there for it! Just try to consider the function of your project before diving in to prevent an undesirable outcome.

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