Know Your Fibers: Cotton vs. Viscose Rayon

The goal of our Know Your Fibers series is to provide up-to-date educational information  about different types of fibers for our Barnhardt readers. In this post, we’ll take a look at how cotton compares to viscose rayon.

 

While cotton and rayon fibers are both made from the same polymer (cellulose), cotton’s cellulose is grown in five to six months by plants. Rayon’s cellulose is produced from trees, which require a much longer time (years) to grow before they are big enough for harvesting.  Some of the tree-related facts with regard to viscose rayon are chilling--while cotton plants are replaced seasonally on the farm, pine trees, for example, take 25-35 years to regenerate after harvesting for viscose rayon. Furthermore, nearly 30 percent of the viscose rayon used in the fashion industry are harvested from ancient and endangered forests worldwide.

The harvested trees go through a harsh chemical process to remove everything (bark, lignin, etc.) but the cellulose, and then the remaining cellulose is regenerated into man-made fibers. Since the molecules in cotton consist of longer cellulose chains than those in rayon cellulose, the longer cotton molecules are also packed more in-line (crystalline areas) with each other than rayon’s more random (amorphous areas) molecules. Both of these molecular qualities combine to make cotton fiber much stronger than rayon fiber.

Amorphous and Crystalline Areas of Polymers

 

Unique Properties of Cotton

The same two molecular properties also lead to the amazing fact that cotton fibers increase in strength when wet, whereas viscose rayon fibers lose strength when wet. Improved wet strength is important for nonwovens like dry wipes that are used to absorb spills, and also for added strength in pre-moistened wet wipes. Higher wet strength is also an asset for medical products that are used to clean and protect, absorb bodily fluids, and even to support organs during surgery.

Regenerated Fibers Are Not Natural

Cotton fibers come from plants and there are many varieties of seeds used to grow it. The type of cotton seed used is primarily determined by the conditions in the area where it is planted (wet, dry, short or long growing season, etc.).  Many farmers use genetically-modified cotton seed to grow a hardier plant that may better withstand the elements and require less chemical application (fertilizer, pesticide) during the growing season. Of course, a small but growing contingent of farmers go the all-natural route and grow cotton exclusively via organic techniques.

Viscose rayon can be produced from any number of trees, grasses or even cotton, as they all get their strength from cellulose. Some rayon fibers are produced using bamboo (which is a grass) as the cellulose donor. In recent years, some manufacturers made false claims, labeling rayon fibers made from regenerated bamboo plants as natural. But when a fiber is made from regenerated bamboo, it is not, in fact natural. The Federal Trade Commission took action, requiring manufacturers to remove the “natural” labeling.

Locally Grown & Processed

While cotton is grown all over the world, the largest share of the market is produced in China, India, and the United States. The US market, representing producers along the southern tier from Virginia to California, is the global standard-bearer for quality. There are no producers of viscose rayon in North America. For every pound of fiber harvested, there are roughly 1.6 pounds of other useful products being created, such as cottonseed oil, cattle feed, and mulch. In fact, over the last 20 years modern cotton farming techniques have reduced the energy used by 66%. In addition, over those two decades water usage has been reduced by 49%, carbon dioxide emissions has been lowered by 33%, and soil loss has decreased by 34%. All of this has occurred while new seed varieties have reduced the amount of pesticides used by 23%. With cotton farming techniques, less will always mean more, especially when it comes to sustainability.

While cotton is locally grown and harvested by conservation and sustainability-minded producers and manufacturers here in the USA, viscose rayon is produced from cellulose harvested from trees in the developing world and processed in high-polluting manufacturing facilities primarily located in China, India, and Indonesia.

Purified Cotton vs. Viscose Rayon Production Steps

Let's look at the steps involved in producing purified cotton and viscose rayon, as depicted in the graphic below. While viscose rayon can be made using any raw scour of cellulose, the vast majority produced commercially uses trees. If you make a side-by-side comparison of cotton and tree-sourced viscose rayon, you can quickly ascertain that the viscose process involves nearly three times the number of steps as those in cotton fiber production.

Not only is the cotton production process far less complex, it’s also cleaner. Cotton production requires fewer chemicals and generates less waste. The source plant is annually renewable on the farm, while trees take a generation to replace. Cotton is the environmentally-friendly choice, and it’s the preferred fiber by consumers for a variety of applications, from clothing to bedding, bath towels, furniture, personal hygiene and baby products.

Cotton vs. Rayon Production Steps

Knowing your fibers means understanding everything about them, from how they are farmed to their distinct properties in a variety of situations. For those looking for a truly natural product that’s soft, absorbent, and strong--even in when wet--cotton is the clear answer.

Editor's Note: This article was first published in December 2013 and has been updated for accuracy and comprehensiveness.

 

 

83 Responses to Know Your Fibers: Cotton vs. Viscose Rayon

  1. I have an area rug cleaning facility. We clean all types of rugs including fibers that contain wool, silk, and “faux silks” like viscose, Tencel and bamboo/banana silk which are all cellulosic fibers. The rug retail industry which sells the rugs is grossly misinformed about these cellulosic fibers. Our industry talks a lot about viscose versus real silk, but this is a very good representation of viscose versus cotton as well. Thank you for this informative article! I really enjoyed it.

    • Hi Raúl,

      Viscose (rayon) is softer than nylon. Nylon is stronger than viscose. Both can be made into a velour fabric.

      We hope this helps!

  2. I just brought 2 sets of Queen sized sheets top bottom and 4 pillow cases each print for 15.00 each. pretty prints. I understand that the absorbency will be low but how can one get around the significant price difference. Even if they last a shorter period of time I can afford to replace old mended sheets to something that looks quite lovely. Cotton for the same would cost 100 to 200 total.

    • Hi Lois,

      The number of threads per inch (count) in sheets is important for softness and durability. Synthetic fibers like polyester are stronger than cotton and will last longer. But they are uncomfortable because they don’t breathe like cotton.

  3. I just bought a garment that is 70% silk and 30% viscose — beautiful and I guess I’ll have to dry clean it. What do you know about silk/viscose blends as opposed to silk/cotton blends (which I have had and like). Do they “breathe” the same way — keep cool in summer?

    • Hi Paula,

      Silk/viscose blend should breathe the same as a silk/cotton blend as long as the construction of the fabrics are the same (i.e. same size yarn, same number of yarns per inch of fabric and same fabric formation -knitted or woven).

      Hope this helps!

      • Dear Matthew,
        Rayon is having 13% moisture absorption & retention properties as against the 7% for Cotton. Hence I think rayon should absorb more Vs Cotton.

        • Hi Ganesh,

          The numbers you are referring to are natural regain (at equilibrium) under controlled humidity and temperature. This does not represent saturation capacity. Also, the natural regain for non-purified cotton is 8%, however Purified Cotton can absorb up to 28x’s its own weight.

  4. I still have three questions (kinda noob and re-affirming):

    1. So what I have understood from the above article is that RAYON is a fiber which can be obtained from wood cellulose and also cotton cellulose. Am I right?
    2. If fiber obtained from cotton cellulose is rayon fiber then what is the fiber made from cotton (not its cellulose) called?
    3. Is rayon knitted or woven? And if it is knitted, kindly mention the fabric names and if it is woven then kindly mention the fabrics names.

    • Hey Arpit,

      1. Rayon is classified in the Textile Fiber Products ID Act as “a manufacturered fiber composed of regenerated cellulose”. The supply of cellulose can come from trees, bamboo, cotton of any other plant material that contains cellulose.

      2. Even if the raw material is cotton it is still rayon if the cotton cellulose has been dissolved and then regenerated into fibers. Cotton used in this process is the linted, short fiber left in the seeds that do not have enough length for textile processing. So they are dissolved and regenerated as longer fibers.

      3. Rayon is the fiber that is spun into yarn. These yarns can then be wover or knitted into fabrics. So rayon can be used to produce both woven and knit fabrics.

  5. Actual which temp. is preferable for washing 12gg sweater under made viscose ? knitted construction is 2/2 rib.

    • Hi Md. Sharifur Rahman,

      It depends on the fabric construction. I would read the label for washing instructions. It should include the proper wash water temperature.

      Hope this helps!

  6. First for clarification…

    Is MODAL COTTON the same as RAYON BAMBOO?

    Two questions from Feb 23 post….
    Is Modal in fact a better insulator – so as a heavy sheet / cover it in fact would be good to stay warm?

    The post says that modal has hard time retaining color. I’ve read that it in fact absorbs colors better than cotton. And from personal exp washing modal cotton underwear – it does retain color no problem.

    Here is Feb 23 2016 post for quick ref:
    …Also, I have used rayon, modal, and bamboo products in my bedding. However, I always get way too hot. So is it the case that although cotton is stronger and performs better when wet, that these other cellulose products are better insulators? And why is that? Are there more breathable forms of cellulose products that maintain that especially silky feel that comes with Modal? I also thought it is worth mentioning that Modal has a hard time retaining color brilliance when washed …

    • Hi Brad,

      Modal is a type of rayon made from Beech trees. It is stronger than rayon which can be made any other trees and bamboo which is rayon made from Bamboo. Modal cotton is a blend of modal rayon and cotton fibers. It will be stringer and resist wrinkling more the rayon, bamboo or those two fiber blended with cotton. The insulation value are all about the same. Fabric construction and yarn size plats the biggest roll in insulation properties. Smaller yarns and tighter weaves or knits provide more insulation than larger yarns and looser weaves.

      Hope this helps!

  7. I like to wear 100% cotton knit when I can find it. Seems manufactures ruin cotton clothing by adding polyester or spandex. Spandex is disgusting and makes my skin “crawl”. I just wish producers/designers would create durable (not the thin materials) in women’s clothing. Sigh!

  8. I know that a cotton blouse would shrink after it is laundered, would a blouse that is labled viscouse shrink? Would I have to buy one size larger in order to insure a proper fit after laundering a viscose blouse?

    • Hi Donna,

      Both cotton and rayon will shrink with washing. Woven fabrics shrink less than knits. However, knit fabrics today shrink far less than they 25-30 years ago. This is because most companies preshrink the knit fabric before it is sewn into a garment.

      Hope this helps!

Leave a Reply

Your email address will not be published. Required fields are marked *