Rayon: A Rug Specialist’s Challenge

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What do artificial silk, art. silk, banana silk, viscose, bamboo silk, allo silk, cactus silk, soya silk, modal, cuprammonium, lyocell, triacetate, and acetate have in common? They are all a type of rayon manufactured from regenerated cellulose (See Image 1).

Designers have embraced the silk-like look of rayon for garments, upholstery fabrics and area rugs. But rayon rugs present many challenges for rug cleaners, as this fiber doesn’t hold up to foot traffic and consumer do-it-yourself spotting/cleaning.  Professional cleaning may exacerbate pre-existing texture distortion. However, techniques are taught at advanced rug cleaning courses that demonstrate how to avoid and or correct texture distortion in rayon and silk rugs (Image 2).

Another problem associated with these rugs is the dyes are not always colorfast. There have also been instances of pattern stencil bleeding wicking to the face and back from the foundation yarns. This stencil bleeding cannot be predicted or tested for prior to cleaning. It is important to get a clear understanding with your customer to avoid any misunderstandings that these issues are pre-existing conditions. You should obtain a written release before cleaning these rugs.

Rayon is the generic term of manufactured regenerated (or reformed) cellulosic fibers produced by four main processes:

In a search for a product that could match the look of silk, a Frenchman by the name of Count Hilaire de Chardonnet produced the first manufactured fiber. In 1891, he dissolved the pulp of mulberry trees (since silk worms feed on the leaves) in chemicals and forced the solution through a metal plate with tiny holes. It was then exposed to heated air and chemicals to harden the material into a filament fiber. He patented the process of making “artificial silk” which resulted in a shiny fiber, but was removed from the market due to flammability issues.

Large-scale commercial production of artificial silk began around 1900 based on a process developed by British inventors, Charles Cross, Edward Bevan and Clayton Beadle. Cellulose from wood pulp or short cotton fibers called “linters” are immersed in a solution of sodium hydroxide (caustic soda) and aged for a time. This results in a solution that is thick and viscose, which gives us the term “viscose rayon.” Then the fibers are forced through a spinneret into a bath of sulfuric acid. 

The confusion between real silk and artificial silk led the U.S. Federal Trade Commission (more on this later) in 1924 to establish the term “rayon” for regenerated cellulosic fibers. The term is actually French, meaning a “ray of light.” This term is mostly used in the U.S. with “viscose” the common term in Europe. To be specific, we will use the term “viscose rayon.”

Because of environmental problems associated with the process, viscose rayon is no longer manufactured in the USA. The viscose process is still the most common method of worldwide production, which is now mostly in Asia. India is the largest manufacturer of the fiber.

A Japanese researcher modified the viscose process to develop a fiber with a physical structure more like that of cotton, having a greater resistance to deformation when wet. This fiber is used for garments with a high-tenacity version for tire cords.

The raw material for lyocell, like that for viscose rayon, is cellulosic pulp. The chemicals used are not as toxic as viscose rayon and the process is self-contained. The fiber is stronger than viscose rayon and mostly used in garments. It is sold under the brand name “Tencel®” and manufactured mostly in Europe. Recently, Tencel came to market for carpet and rugs as it “feels silky and soft.” Tencel, when used for garments, will shrink 3% after the first washing. This is not a problem for rug cleaners unless it is used in the backing or foundation yarns.

This process is different from the viscose rayon process. Cellulose is dissolved in a copper ammonium solution with the fiber extruded into a water bath. It is somewhat more silk-like in appearance and a bit stronger. The fiber is made mostly into lightweight fabrics. Due to clean-water regulations it is no longer produced in the USA.

What we commonly encounter as rug cleaners is viscose rayon used as a design highlight, woven carpet fabricated into an area rug, and rugs made from 100% viscose rayon. The label could read “artificial silk” or abbreviated as “art. silk” (with or without the period after art). Some viscose rayon rugs can be expensive. Unfortunately, some consumers may have overlooked the “art” part of the “silk” label and paid a considerable amount of money for the rug (particularly if the rug dealer was not forthcoming). The consumer is often convinced they have true silk rug.

The viscose rayon rug may have pre-existing pile distortion so be sure to document that fact on your inspection form. Discuss this issue with your customer. Cleaning may not improve the look and may create additional distortion. During the cleaning process, viscose rayon, when wet, loses 30 to 50% of its strength (according to the Apparel/Textile Industry’s Fabric University). The back-and-forth movement of a carpet cleaning wand can cause pile distortion and high water pressure makes the damage worse. Hot water can cause the viscose rayon to bleed. It is recommended to turn down the pressure and the heat and avoid the typical back-and-forth wand movement used in wall-to-wall carpet cleaning. Due to its physical structure, low wet strength (or tenacity) is the Achilles heel of viscose rayon. Other natural fibers such as cotton and wool have a higher tenacity.

After cleaning viscose rayon rugs, set the pile towards the bottom of the rug with a good carting brush (See Image 3). Vacuum the rug the next day to lift and soften the pile.

So what about banana silk, bamboo silk, and soya silk? Trust me, bananas do not have silk. These are marketing terms used to disguise the fact that the rug is made from regenerated cellulose (i.e. viscose rayon).

Our friends at the Federal Trade Commission have taken several large retailers and manufacturers to court over false labeling. They have called it “bamboo-zling” (maybe they do have a sense of humor after all). The FTC has issued million dollar fines for advertising “made from 100% bamboo fiber,” “antimicrobial,” “biodegradable” and “eco-friendly fiber.” This includes companies such as Amazon.com, Leon Max, Macy’s, Sears, and Kmart who continued to make those advertising claims after the FTC sent them a warning letter. The proper label is “Rayon made from Bamboo” – it is not a “green” fiber. 

As you can see, viscose rayon is a problematic fiber. Read the label if it is still on the rug. Doing a simple burn test will tell you if it is real silk (burning hair odor) or rayon (burning paper). Silk has its problems too, which we will cover in a future article.   

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