trilobal polyester

Why doesn’t Superior sell Rayon thread?

Occasionally we are asked why we do not have any rayon thread. After all, rayon is the most commonly used thread in the embroidery industry, is relatively inexpensive, and has a beautiful sheen. The answer is because rayon is weak and usually is not colorfast. It is not the recommended quality fiber for quilting or embroidery.

What is rayon? Unlike cotton thread which is made from a natural source and unlike polyester which is made from man-made polymers, rayon (commonly referred to as viscose rayon) is a mixture of nature and manufacturing. The textbook definition of rayon is "a manufactured fiber composed of regenerated cellulose." The major source of cellulose required in the creation of rayon is wood pulp, which is produced from timber. After the bark has been removed, the wood is chipped into very small pieces, boiled under pressure, chemically treated, washed, and then dried.  The final product is a hybrid material called viscose rayon.

Colorfastness  Accepted definition: Fabric and thread is colorfast if its colors and dyes do not bleed or run from the clothing. Fabric and thread should be tested for colorfastness before using any type of bleach or bleaching solution, or strong cleaning product.

  • Make sure you understand how the brand defines colorfastness.  Some claim their rayon thread is colorfast because it will not fade in cold or hot water. That is not the generally accepted definition of colorfastness. To most, colorfastness is the ability to be washed and worn without the color fading or running. Does washing include bleach, detergents, or brightening agents?  Test it before you use it.

An example of a popular brand of Rayon marketed as "Colorfast" compared to Superior's Rainbows trilobal polyester.  Both have been treated with bleach on the right half of the image. Notice how there is no change in color to Rainbows while the Rayon thread loses complete color.

rayon polyester bleached
(Photo credit: Anita Zobens, The Cottonmill Threadworks - Superior Educator for Canada)

Where is rayon made?  Rayon is no longer made in the U.S. In 2004, the last of the U.S. rayon production facilities were closed due to EPA regulations.  Current rayon producing countries include China, India, and some European countries.

If not rayon, then what?  Because we cannot take the chance of our thread fading or running or bleeding, we do not use, sell, or recommend rayon thread.  The better choice is trilobal polyester. Trilobal poly has the same high sheen as rayon or silk but is stronger and is colorfast. It costs more than rayon, but the quality and peace of mind are well worth it.

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By: Bob Purcell