What are the reasons to choose one fibre over another - are there advantages and disadvantages for each type of fibre? If I have a pattern that specifies wool, is it usually safe to substitute for cotton, or vice versa?

  • 4
    I feel that this is a topic which could be answered with many pages, making it too broad. However, a more focused version (e.g. "Can I substitute cotton for wool in most situations") may work -- although may still need to be narrowed to a particular pattern or project.
    – Erica
    Apr 27, 2016 at 17:01
  • I kind of agree - but consider the alternative: tens of almost identical: "can I substitute x for y" questions. A single canonical might be better? Apr 27, 2016 at 17:47
  • If we define the question as "does the fiber make a difference or can I substitute willy-nilly", we can unequivocally state "yes, it makes a difference, substitution requires research", without going into pages and pages of how they differ and when to choose each one.
    – Belisama
    Apr 27, 2016 at 21:19

2 Answers 2


Each type of fiber has unique characteristics that must be taken into account when considering substitution (which is pretty much a pattern-by-pattern process). Some examples:

Machine Washability Silk and pure wool arn't machine washable, cotton and most synthetics are, linen is actually improved by being machine washed.

Breathability All of the natural fibers (wool, silk, cotton, linen, etc.) breathe, but the synthetics (acrylic, polyester, etc.) don't.

"Stickiness" Certain techniques (drop stitches, felting) require the built-in self-gripping of wool and similar animal fibers. This also impacts things like cotton's known tendency to droop.

Elasticity This is the fiber's ability to stretch and contract, which affects an item's ability to regain its orignial shape as well as how wearing the yarn is to knit with (hand fatigue). Animal fibers and some synthetics are stretchy, while plant fibers aren't.

Allergies & Sensitivities Wool is the infamous one in both these categories, though synthetics can be problematic, too. Plant fibers do better.

In general, the closer you stick to the recommended fiber type, the more predictable the results will be (replacing cotton with wool is riskier than replacing it with linen). If you really want a specific substitution, you can try contacting the designer for their thoughts; also, if you're on something like Ravelry, you can see if anybody else has tried it.

  • Elasticity is a great point, and the first thing I thought of.
    – user24
    Apr 27, 2016 at 16:29
  • What are you creating? Think about what properties you want your finished creation to have. It's important to distinguish between Fiber Type, Yarn Type (loose/tight), & Fabric Construction (loose/tight knits or wovens). IN GENERAL, washability, "stickiness," allergies, & breathability are relevant to Fiber Type, and to a greater degree, washability, breathability & elasticity are relevant to Yarn Type & Fabric Construction. Also consider coolness/warmth. Each stage of textile production from fiber to yarn to fabric and dyeing & finishing brings its own set of properties & trade offs.
    – user1798
    Jun 26, 2017 at 23:21

From the Craft Yarn Council:

"Can I substitute one yarn weight for another yarn weight?

No, each project is designed to be made with a specific weight of yarn. Changing the yarn weight will change the size and appearance of the finished project as well as change the amount of yarn required.

Can I substitute different yarn brands of the same yarn weight?

Yes, but be sure to test the “gauge” to make sure that an adjustment is not necessary as you substitute one yarn for another. See question # 8 to learn more about “gauge.”

As for some of the differences between various yarns this Wikipedia link shows some difference from the various types of yarn:


"All varieties of cotton have a dull finish unless mercerized. Cotton yarn has minimal elasticity unless blended with other fibers. Pure cotton is useful for projects that require structure such as purses and tote bags, placemats, and other utilitarian items.


Egyptian cotton Longest cotton fiber, smoother and softer than other cottons.

Pima cotton Cross between Egyptian and American cottons. Intermediate properties.

American cotton Medium-long fiber, readily takes on dye. Available in widest variety of colors.

Other plant fibers

Linen Strong fiber, good for warm weather items. Wrinkles easily.

Bamboo bast Similar to ramie, possesses an elegant sheen. Not to be confused with the more common bamboo rayon.

Animal based fibers


Merino wool Softer than cotton, tends to pill..

Icelandic wool Strong but scratchy.

Mohair Lofty and luxurious, best used as an outer layer. May feel scratchy.

Cashmere Soft, luxurious, expensive.

Alpaca Very warm. Suitable for accessories such as scarves.

Angora Very soft, tends to shed. Best used in pure form as an accent material, or blended with other fibers.

Silk Exceptionally strong, lustrous, and shiny. Good for summer wear.

Synthetic fibers


Acrylic Washes well, inexpensive. Good choice for beginners and for items designed for babies or pets.

Nylon Strong, elastic, washes well. Not ideal for garments unless blended with other fibers.

Rayon Made from processed cellulose (e.g. wood pulp, bamboo, seaweed) extruded into threads. Inexpensive and highly absorbent, natural sheen."

  • 1
    Not sure if you are in the process of doing it but this could benifit from some formatting to help logically break up your yarns. Use of bolding or headings would be an asset to make this easier to read. Also use > quotes if this text is not your own.
    – Matt
    Apr 27, 2016 at 12:51
  • Cotton is also a plant fiber. It's a cellulosic, as is rayon (believe it or not!). This question is entirely too broad, requiring a complex answer. End-use textile proerties are dependent on more than just fiber type - one also has to consider yarn type, fabric type, and dyeing and finishing. And within a fiber type there are a broad range of processing variables and properties.
    – user1798
    Jun 26, 2017 at 23:31

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