Viscose or rayon is a synthetic product used as a textile material that is obtained by treating cellulose with a solution of caustic alkali (alkaline substance) and carbon disulfide (volatile liquid used to manufacture certain cellulose fibres).
Viscose gets its name because it is an organic liquid with viscous or sticky characteristics. This is used to make rayon, although rayon itself is called viscose in Europe, and so both have become synonyms, referring to the textile fabric used for making garments and accessories.
What is the composition of viscose?
The main material of viscose is cellulose, which is the most abundant biomolecule in nature. It is a homopolysaccharide (i.e. a polysaccharide whose molecules are composed of the same type of monosaccharide) composed solely of glucose molecules. More simply explained, cellulose is a fibre of plant matter that is made up of glucose.
Cellulose, the main component
Cellulose is found in many parts of nature. It can be found in wood, straw and other plants in large quantities. This is the fundamental component of the wall of plant cells in plants, wood and natural fibers. It can be found in high concentrations in cotton fibers, which may contain up to 90% cellulose, thus being a very pure source of obtaining this compound. It is found in such abundance in these elements because cellulose works as support and protection for them, serving as a kind of support.
Seen in more understandable numbers, a plant cell from a piece of common young wood may have about 40% cellulose in its composition, while other types of trees, such as woody, may have about 50% cellulose, and in its purest state can be found in cotton, with a composition of up to 90%.
History of viscose or rayon
In order to talk about the history of viscose, it is first necessary to know the history of cellulose, which is what it is composed of.
Cellulose was discovered in 1838 by Anselme Payen, a French chemist, physicist and mathematician, who managed to isolate it from vegetable matter. But it was not until the 1880s that cellulose was used to create viscose to replace silk.
This discovery was made by Hilaire de Chardonnet in Échirolles, France in 1884. Hilaire was a French count as well as a scientist, who was known for the manufacture of artificial silk (viscose or rayon) and a textile industry for its production.
He tried to apply the appropriate solvents to the cellulose, and thus obtained a dense, viscous solution, which he filtered through a plate in which he had previously drilled tiny holes. He realised that when this process was finished, the liquid formed small filaments which, once dry, were easy to adapt to spinning and weaving techniques. Thus it was that Hilaire de Chardonnet obtained the rayon for the first time, realizing that it was very similar to silk in its properties, with great resistance and elegance, so it became known as artificial silk.
By the 1890s, Charles Frederick Cross in the company of Clayton Beadle made a decision to use viscose again, and so attempted the production of rayon. Their attempts became the basis for their production, until success was achieved by the Swiss chemist Jacques Brandenberger working in Switzerland and France.
Rayon was first known as artificial silk, until later, around 1924, it became known as rayon or viscose in Europe and other countries. This was manufactured like a thread in its beginnings to make embroideries and yarns, until later the manufacturers realized that the discarded fibers could be interwoven to form more complex accessories. Since then the viscose was being improved over the years and its quality was increasing.
By 1940 it was improved to a high tenacity rayon, and by 1950 to something known as HWM or modal rayon. The latter, in addition to having high tenacity, also has high elasticity and wet strength.
Types of rayon and their characteristics
There are several types of viscose or rayon, which vary in quality and composition. Each has its own distinctive characteristics, although all derive from the characteristics of normal rayon, which has been known since its inception as artificial silk. Other known types are high tenacity rayon, which has much greater strength; HWM rayon, which is more resistant to water and moisture; cuprammonium rayon, which contains additional chemicals to give it other effects; and rayon acetate, which differs in its manufacture.
The first is normal rayon, which has always served as a substitute for silk. The problem with this type of rayon is that its resistance decreases over time, which causes it to deteriorate noticeably and its quality is compromised. In addition, its elasticity is also quite lost compared to other elastic fibers, and when it gets wet its quality decreases even more, demonstrating that it is not very resistant to water.
It is characterized by its touch, being very similar to silk (hence it is known as artificial silk), in addition to having its own brightness and unique beauty. It is therefore widely used for the manufacture of lingerie and other clothing.
It is mainly used in the textile industry for the manufacture of clothing, such as t-shirts, blouses, skirts, trousers, dresses, curtains, etc..
And in other areas, such as the manufacture of accessories for interior decoration, such as bedspreads, blankets, upholstery, etc.. Also in the industry for the manufacture of certain surgical materials and other non-woven products. And in some cases for some the confection of products for feminine hygiene.
Modal Rayon or HWM Rayon
The improved version is the HWM or modal rayon, which is stronger and more durable. It has the characteristic that it has a great absorption, which makes it more resistant to water, and its elasticity is not so compromised when getting wet. Because of this it can be washed in the washing machine, in contrast to normal rayon.
It has the same characteristics as normal rayon, in addition to some improvements:
– Its elasticity improves its soft touch, offering a more pleasant sensation, as if it were the rose of the skin.
– It is more absorbent than cotton, allowing moisture absorption of up to 50% more and more quickly and effectively.
– Its silky smooth shape allows it to have a brilliant effect.
– Since it is a modified and improved version of the normal rayon, HWM is more resistant to water and humidity.
– It has great versatility, allowing it to have the same properties of comfort and touch as other natural fibers such as silk, wool or cotton.
– Its great absorption allows you to retain the dye very easily, so you can change its color without many problems.
– Unlike other fibers it does not isolate the body from temperature, allowing perspiration to be possible. This makes the cold penetrate more easily into the skin, making the modal ideal for hot climates.
– Unlike other scratches, the modal does not shrink or lose its properties when wet, or at least shows a much greater resistance to water, allowing it to be washed in a washing machine along with other garments.
High tenacity rayon
Another type is high tenacity rayon, which has a resistance up to twice that of modal. Due to its high strength is often used in industry, so much so that in the 1930s was normally manufactured for use in tires, hoses and timing belts, although later was devoted to the manufacture of clothing, to see that they could be preserved for longer.
There is also a type of rayon called cuprammonium rayon, which is manufactured by a process in which viscose is combined with copper and ammonia. Its properties are very similar to that of normal rayon, but its manufacturing process produces adverse effects on the environment, so its production has been reduced or stopped altogether.
This is basically like normal rayon, only that it differs because the yellow paste dissolves in acetic acid after the xanthantation process.
The acetate rayon does not melt, it burns quickly leaving a small ash trail where it was made. It is synthesized from 80% cold sulphuric acid. In addition, it is sensitive to heat and requires precautions for ironing. It must also be dyed with anilines. It accepts dyes very easily, allowing it to be dyed in many colors in a simple way.
Because of its complications, this is less common on garments.
Chemical composition of rayon
Rayon is 100% cellulose and has the same chemical composition as the natural cell. The molecular structure of rayon is the same as that of cotton and linen, except that the molecular chains are shorter and do not form as many small crystals.
Serving a little chemistry to know its composition, it can be added that cellulose is a long chain polymer of variable molecular mass and with an empirical formula represented by (C6H10O5)n, where the value of n is at least 200. It is formed by the union of molecules of β-glucopyranosa through links β-1,4-O-glucosidic. By glucose hydrolysis.
The structure of cellulose can be observed as follows:
As for viscose, it is characterized by longitudinal lines called striae. The cross-section is a circular form of sawn edges.
The shape of the fibres is due to the presence of zinc sulphate in the spinning bath and the loss of liquid from the fibre surface during coagulation. The indented form is an advantage when it comes to the absorption of dyes, hence its easy coloration.
Its structure can be seen as follows:
Is viscose environmentally friendly?
In order to know if viscose or rayon is ecological, first you have to know about the material from which it is made.
Before being converted into a continuous thread, viscose has been a wood, cotton or even a tree that has been transforming CO2 into cellulose for more than two decades through photosynthesis. Having said this, it can be concluded that viscose is a fabric composed of noble and natural parts.
Of course, several chemicals have been added in the process for improvement, but depending on the type of rayon this could be more or less ecological.
It is true that it is called artificial silk, and is obtained artificially, but still has a certain amount of natural materials that give it ecological properties. It is almost twice as absorbent as cotton, and its properties make it highly breathable, shiny and quite smooth. Due to this, its use and manufacture has been increasing.
Despite this, it cannot be ruled out that the majority of viscose production today uses large quantities of toxic chemicals to convert the raw material into fiber. Moreover, if its supply is not well managed, the wood may come from old and threatened forests, causing deforestation and forest degradation.
Despite this, the purest rayon garments are kept with as many noble and natural products as possible and with as few chemicals as possible, so they are mostly ecological garments.
How is rayon or viscose produced?
Its main material is cellulose, which comes from wood or cotton fibres, and which is treated with sodium hydroxide and then mixed with carbon disulphide to form cellulose xanthate, which is then dissolved in more sodium hydroxide. The resulting viscose is extruded in an acid bath either through a slot for making cellophane, or through a small hole for making rayon.
The acid converts the viscose back into cellulose.
At first, the cellulose is reduced to pulp and, after being purified, it is extended until it takes the form of a sheet. After the use of different chemical substances, which will vary according to the different methods used, the solubilization will take place. As a result of this first treatment, a viscous liquid is obtained, which is poured through a row.
This is how the characteristic filaments are acquired, which adopt the desired consistency thanks to the evaporation of the solvent with which the cellulose has been treated, or through coagulation baths. Once dry, the filaments are twisted, ready for the spinning process.
The manufacturing process varies according to the procedure used, which is different depending on the factory and the chemicals or attachments you want to use, depending on it is called rayon, viscose, cellulose acetate or Bemberg.
The standard manufacturing process is as follows:
- First the cellulose is acquired: To begin with the process of elaboration of viscose or rayon it is first necessary to acquire the cellulose to process.
- Immersion: The cellulose to be dissolved in caustic alkali or caustic soda.
- Pressing: The solution is pressed by large pressing rollers, which remove excess liquid.
- A white paste is produced: The pressed plates are broken or crushed to produce what is known as white paste.
- The result is aged paste: This is achieved by exposing the white paste to the effects of oxygen.
- Xantation: The aged white paste is mixed with carbon disulfide (CS2) in a process known as xanthantation.
- The yellow paste is produced: The singing process modifies the composition of the cellulose mixture resulting in another paste called yellow paste.
- Viscose is finally obtained: The yellow paste is dissolved in a caustic solution to form the famous viscose.
- The product is matured: The viscose is left to rest for a while until it is sufficiently mature.
- Filtration after ripening: After ripening, the viscose is filtered to remove any particles that could not be dissolved.
- Degasification: Pressure is exerted to remove any air bubbles left in the viscose.
- Extrusion: The viscose solution is extruded through a mould with very small holes.
- An acid bath is carried out: When the viscose is removed from the perforated mould, it is immersed in sulphuric acid and kept there, after which the rayon filaments are obtained.
- Stretch: The resulting filaments are stretched to strengthen the fibers.
- It is finally washed: The stretched fibers are washed to remove any chemical residue. If the result you want to produce is filaments, the process stops at this step, otherwise you continue with the interweaving to form fabrics.
Uses of viscose or rayon
In the beginning, viscose was used to coat fabrics, which proved to be quite appropriate as it greatly improved the coating. However, when Charles Frederick Cross and his colleagues tried to make solid objects such as umbrella handles, they found it too fragile.
The development of viscose technology was continued and later the production of yarns for embroidery and decoration. Finally, with the incorporation of Samuel Courtauld & Co. into the business in 1904, the manufacture of viscose became important.
But over time the use of viscose became less and less common due to the polluting effects of carbon disulfide and other chemical by-products added to the process, which forced the closure of the Bridgwater factory in 2005.
Today, rayon is mostly used in textile manufacturing (for clothing such as blouses, dresses, jackets or lingerie), in interior decoration (such as bedspreads, blankets or curtains), in industry (for the production of surgical material, non-woven products or tyre frames) and for other uses (such as for the manufacture of feminine hygiene products).
To put it more clearly, it is used for:
- Clothing: Clothing accessories such as blouses, dresses, jackets, underwear, hats, trousers, t-shirts, sportswear, elegant suits, and so on.
- Interior decoration: bedspreads, blankets, curtains, upholstery fabrics, sheets, covers, tablecloths, etc.
- In industry: For the coating of industrial products (e.g. high tenacity rayon), the coating of surgical medical products, non-woven products or for the coating of tyres.
- Other uses: For the manufacture of some feminine hygiene products.
Does rayon have any drawbacks?
One of the disadvantages of some types of rayon is its low resistance, especially in the wet state; in addition, it has the least elastic recovery of all the fibres. However, HWM rayon, or modal fiber, is much stronger and more durable. The recommended care for normal rayon is based on its dry cleaning. HWM rayon, on the other hand, can be machine washed.
In other words, the common drawbacks of rayon are its low water resistance (if not HWM rayon), its delicacy and its ease of wrinkling.
But these drawbacks can be controlled if you treat it with delicacy and care, always taking with you what the label says for washing and preservation.
If treated with due care, rayon will present no more drawbacks than any other elegant garment.
How to care for or treat rayon garments?
Rayon garments form a group of synthetic fabrics. Their manufacture and manufacturing materials make intimate garments and household items made of this compound have an appearance and feel similar to cotton and silk, although depending on their type may weaken and shrink when wet, or may have a reduced durability depending on the treatment they are given.
Also the dye they have absorbed can quickly become detached with a bad treatment, causing them to fade in a short time. So the care of this type of rayon or viscose garments requires a special treatment, which can be followed in the form of steps, which can be easy for those who already know the process.
In many cases rayon garments are not very durable, as they are delicate in some cases, and are very sensitive to today’s classic washing mode, which causes them to shrink in most cases. So it’s a good idea to read the label before entering the washing machine.
With a detailed guide it is easier to know how to care for rayon garments, so following these steps could increase their useful life.
The Right Way to Wash Rayon Garments and Accessories
The first and most important thing is to read the garment label even before you buy it, to know if you will be able to go directly into the washing machine or if you will have to wash dry.
It is not all rayon garments that can get wet, for example, normal rayon garments do not have good water resistance, in contrast to modal garments. It is therefore advisable to check the label first to see if it is safe to put them in the washing machine. If you indicate the opposite, you must take into account that when cleaning them you must take greater care to preserve them.
If the label indicates that they can be inserted into the washing machine, it means that they are made with HWM rayon, which makes it safe to wet them. These are recommended for people who do not have much time or do not want to make extra effort to clean them, as they can enter the washing machine along with their ordinary clothes and thus save a lot of time. This is also possible if the rayon has been mixed with some other resistant material that provides water resistance.
Whatever the method of washing, it should be borne in mind that rayon is a fragile material and should therefore be treated with care, otherwise it may fade, shrink or even tear while being cleaned.
Even more careful: dry cleaning
If you prefer a rayon garment that can’t be wet anyway, but you don’t have the time or interest to dry clean it personally, you can consider that there are centers that do the work. The cleaning centers have professionals who know how to treat garments and accessories of all kinds, just tell them to give them extra care. And this can be considered for any rayon garment, even for modal if you want to take more care of them.
The only thing to keep in mind is that cleaning centers can have a high cost for dry cleaning depending on the garment and its extension and care. So you should consider that, if the piece is very large, as in the case of curtains, the cost of dry cleaning could be much more than desired.
A little more considerations
And if you don’t have that extra money to send them to the cleaning center, then you might consider setting aside a little time on weekends to hand wash them. The effort is greater, but it will ensure the durability of the garment, as long as it is done conscientiously.
If one chooses to wash it by hand, the label can be useful to know the necessary considerations, because it can say what should be taken into account. A little mild detergent and water at room temperature or warm is usually enough to keep the garment soft.
The steps to follow, in case they are not known, are actually simple. You should fill a tub or a large container with warm water and mild detergent. For the detergent you can ask at the center where you get one that is suitable for garments that require special care.
Once the tub or container is prepared with the correct amount of water and detergent, you should carefully soak the garment and stir it inside, always with gentle and delicate movements, as some of these garments can weaken with water and tear if they are applied too abrupt movements. This process can take up to five minutes, which will be sufficient to remove any type of dirt.
Then it should be soaked with water at room temperature slowly until all the foam has been removed, after which it should be squeezed with extreme care not to cause irreversible damage.
Finally, you can hang the garment in the sun until it dries completely outdoors, which should be done when the sky is clear so that the sun’s rays do their job and do not stick unpleasant odors to the garment, which can happen if you let it dry on a cloudy and humid day.
It is recommended that you dry this way and not with an automatic dryer, as dryers can be too abrupt for the rayon fabric and could tear it.
Smoothing and ironing measures for rayon garments
Extreme care should be taken not only when washing rayon garments, but also when ironing or smoothing them. These fabrics are delicate in every way, and ironing them incorrectly could shrink, fade or burn them.
For ironing rayon garments it is advisable to use the low temperatures of the iron, as high configurations of the same can burn.
The proper method when doing this task is to pass the iron in straight lines and raise it immediately to return from the starting point, not return and go forward again, as is common with other garments. This could cause a lot of tension in the rayon, so be careful with such movements is recommended.
It should also be noted that rayon garments could take a little shine when coming into contact with the heat of the iron, so you can take into account when knowing if you want to iron for the front to retain the shine or the other side to hide it when dressing.
Or you can also consider using a protective barrier on the garment to avoid this shine that leaves the heat. This is achieved by placing another garment that acts as a barrier, something like a fine towel that supports contact but allows heat to pass through so that the rayon can be ironed.
Some people often use aluminum foil, but this is not recommended because if not done with extreme care the aluminum foil could overheat and burn the rayon.
This method could be more tedious and durable, but the result is just as good and will preserve the garment longer, so the effort is worth it.
As a last consideration, it should be taken into account that some rayon garments do not withstand much water, so it is advisable not to steam them to prevent them from shrinking or losing their strength.
A spray could save you the ironing
There are certain anti-wrinkle sprays that can prevent you from having to iron and can be applied to almost any fabric. They are easy to obtain and easy to apply, just spread the rayon garment on a board and apply the aerosol over the entire surface, avoiding stretching the fabric.
Even so, you should read the aerosol instructions to know if it is safe for rayon garments, as not all can be applied to all types of fabric.
Care when laying or storing rayon garments
When storing or placing rayon garments in the wardrobe, bear in mind that they are delicate and should not be treated in the same way as cotton or any other more resistant material. It is best to hang them on hangers in a wardrobe, so that they are loose and free. If it is folded or hung on its side, the rayon may wrinkle or you can make a line that is only removed with the ironing, so it is better to hang them properly.
If you do not have hangers or space to hang them and must fold, you must take into account to do it by the seam lines, so that it does not wrinkle in inadequate areas.
And if the rayon garment is too wide, as in the case of curtains or bedspreads, must be folded carefully, because they can not hang. In these cases it would be advisable to get some plastic box to keep it safe, so that it can be rolled without problems inside. When rolled it could cause wrinkles, but lighter than when folded. And if the garment has wide seam lines, you can fold them to avoid wrinkles or additional lines.
Finally, if the garment will be stored for a long time, you can consider covering it with a special bag to avoid other evils that could cause irreversible damage, such as dust, cockroaches or moisture.
Is a rayon or silk garment preferable?
The answer will depend on the taste of each person. A silk garment cannot be compared in quality, but it can be more expensive. A rayon garment, on the other hand, provides the same feel and elegance at a lower price.
Rayon garments can be delicate, which can be the most negative point, but with proper care they can be preserved for a long time and maintain their brightness and quality, so rayon garments can be a good match in all senses: beauty, softness, shine and feel. Because of this you can consider opting for rayon garments whenever you are going to give them the right treatment.