All about silk

2020 April 3 | Ada

Silk is an absolute classic, sought after for its beauty and exquisite softness, shunned for its price tag and supposed frailty. But is natural silk really so expensive or so impractical? How many kinds of silk are out there? And what makes silk so utterly irresistible? Let us clear up some questions (and bust some myths) for one of nature’s most intriguing materials.

silk fabrics and silk cocoons

What is silk?

Let’s get it clear at the outset that this article focuses exclusively on natural silk. You may occasionally (at other online shops) run into synthetic materials mislabeled as “silk.” It’s a nuisance that none of us can do much about aside from arming ourselves with a little knowledge up front.

So, what is natural silk? The dictionary definition of natural silk is simple: Silk is a fine, strong, soft, lustrous fiber produced by silkworms, particularly mulberry silkworms, in making cocoons and collected to make thread and fabric.

Our own definition is just as simple: Silk is a wonderful, beautiful, unique material that deserves a place in every wardrobe. No matter what anyone says, no synthetic material can reproduce the qualities of natural silk.

Three life stages of the mulberry silkworm, whose cocoons give us natural silk

Natural silk is secreted by the glands of silkworms, particularly the mulberry silkworm, who spin the cocoon from which silk fiber is collected.

The story of silk goes back a very long time. Thousands of years ago, it was the exclusive domain of the Chinese imperial court. From there it went on to become a rare and exotic import that only the very wealthy could afford. Today’s silk is certainly less costly than it once was and it’s no longer the case that silk fabrics are a delicate luxury not to be squandered on everyday clothing. Silk comes in a number of varieties and finds its way into anything from fancy ballgowns to casual separates.

Top-selling silk fabrics at Sartor Bohemia

Natural silk organza at Sartor BohemiaNatural silk chiffon at Sartor BohemiaNatural silk satin, silk charmeuse, at Sartor BohemiaNatural silk dupioni at Sartor Bohemia

Qualities of natural silk

The wonderful qualities of real silk far outweigh its few drawbacks. What are they?

We could probably start by praising silk’s softness and breathability, but to be honest, we love it for its sheer beauty. Silk fibers have a perfectly smooth surface. If you were to cut one, the cross-section would look like a rounded triangle. That’s where silk’s unique luster comes from. No other material is like it. Equally extraordinary is the elegant drape of fine silk fabrics (chiffon, crêpe de Chine, satin) and the wonderful, papery folds of silk taffeta, dupioni, or duchesse satin. What’s more, real silk takes dyes extremely well and you’d be hard pressed to find anything that surpasses the brilliant hues of dupioni and habotai.

Natural silk fibers to other textile fibers under a microscope. The source of silk’s unique qualities is immediately clear. It has a flawlessly smooth surface and a characteristic triangular shape.

Comparing natural silk fibers to other textile fibers under a microscope, the source of silk’s unique qualities is immediately clear – it has a flawlessly smooth surface and a characteristic triangular shape that gently refracts ambient light. This is what gives it that soft, silky sheen.

Practical factors are certainly also important. As we mentioned above, silk is soft – one can barely feel it against the body. It is fine, smooth, and kind to the most sensitive skin. Even “rougher” weaves like georgette or spun silk are extremely pleasing to the touch.

Silk breathes (yes, even thicker silks like duchesse) and this gives it a cooling effect. This is doubly true of fabrics like crêpe de Chine and silk satin or silk charmeuse. Softer materials that don’t have such a smooth surface (silk jersey, silk blends, wild silk, spun silk) tend to feel a shade warmer.

Like other natural materials, silk neutralizes odors rather than trapping them. If you exercise regularly, you know that you have to throw your workout stuff into the washer right away. While we don’t recommend silk for your daily workout, you’re sure to appreciate its odor resistant quality in blouses, ballgowns, and silk lingerie.

Silk doesn’t get moldy like cotton and moths don’t nibble holes in it like wool. Just be sure that it doesn’t lie folded in your closet for too long, or you may find yourself with creases that can’t be ironed out. This especially applies to garments that you don’t wear often (evening gowns) and fabric that’s waiting in your sewing room to be made into something lovely.

Silk is sensitive to high temperatures, so you should follow care instructions when washing and ironing (lukewarm water, a cooler iron). And be careful, some of the most exclusive silk fabrics (duchesse satin, taffeta) shouldn’t be allowed to get wet at all.

For more tips, see our article on how to care for silk.

One of silk’s admitted downsides is that it tends to wrinkle, a quality typical of natural materials. Of course, not all silks are especially prone to wrinkling and some hardly wrinkle at all (for example silk elastane blends). Find out more about how individual fabrics behave, including wrinkling, in our article on types of silk fabric.

Find out more about how individual fabrics behave in our article on types of silk fabric

Find out more about how individual fabrics behave in our article on types of silk fabric

How natural silk differs from synthetic imitations

Here at Sartor all of our silks are made of real, natural silk fiber. Unfortunately, the same doesn’t always apply in other shops. Sometimes that’s due to ignorance or a confusion in terms but sometimes it’s just plain underhandedness.

What is artificial silk? The term “silk” in theory can be applied to any “endless” fiber referred to as filament. Mulberry silk is the only natural material that falls into this category (of course it’s not actually endless, just awfully long). Then there are the synthetic filaments. Polyester or viscose silks are long, smooth, artificially manufactured filaments meant for production of imitation silk fabrics.

At some other shops, you might run into fabrics labeled as “silk” that are actually composed of polyester or rayon. This doesn’t necessarily have to be a conscious attempt to defraud customers; it may be just plain ignorance. According to current textile labeling laws (in Europe this is Regulation (EU) No 1007/2011) the word “silk” can only be used to indicate fibers obtained exclusively from silk-secreting insects – in other words real, natural silk. If you have doubts about the content of a fabric, ask before you buy, or test a sample yourself.

Exercise caution when buying fabric from sources outside of the EU. Textile regulations elsewhere may not be the same and “silk” might be used more loosely. If it doesn’t say “100% natural silk” it may very well be a synthetic.

Recognizing and buying real silk

You don’t need an advanced degree in textiles or years of expertise working with fabrics in order to recognize whether what you’re buying is natural silk. All you need is a little knowledge and a dose of caution.

Read the label

This may seem obvious, but it bears saying: Don’t just look at the product name, written in big, bold letters at the top of the page… you’ve really got to read the small print, scroll down to the textile content, if it’s there at all. The “silk dress” you’re looking at may have just a tiny percentage of silk fiber (or may be entirely synthetic… and “silky” in appearance only). When shopping online, you’ve got to rely on the merchant to provide accurate content information. If it’s a shop you don’t know, or you have any doubts, read the description very carefully. Be aware that merchants can get creative with the product name just to get you to click through. There’s no law against naming a product “silk satin” when its textile content is actually 100% polyester. If you keep your eyes open, you’ll see that “silk” or “silky” is very often used in product names just to indicate a fine, supple fabric regardless of content. If the merchant doesn’t provide textile content information at all, be on your guard.

Every bolt of fabric – this one is natural silk – should be labeled with its textile content

In the shop, every bolt of fabric should be labeled with its textile content.

You get what you pay for

The price itself may give away a silk imposter. You’re not likely to find real silk for the cost of polyester (though it’s not impossible that an honest merchant may offer natural silk at a small margin for less than someone else who sells a high-priced synthetic under slick “expensive is exclusive” marketing logic.) Other factors may affect the price: Whether the fabric was bought on order or acquired as overstock from the factory (often with no difference in quality), whether it was purchased directly from the source or through a number of middlemen. If it’s a special collection with printed graphics created by a designer, their fee will also be reflected in the cost.

The fire test

If you have a fabric in hand, it’s pretty easy to test whether it’s genuine. You can use this trick for unlabeled garments too, like a hand-me-down dress or something from a thrift shop. Just take a small bit of fabric – a few threads are enough – and set it alight. Some fabrics have warp and weft yarns of different materials, or a single thread may combine more than one material. If you don’t get a clear result, try pulling the threads apart and testing them separately.

Natural silk may be sensitive to heat, but it doesn’t burn very well. If you expose it to an open flame, it will smolder reluctantly, but will extinguish almost the moment you pull it out. Scorched silk fiber is black and there will be a hard, black knot at the end of the thread that you can crumble between your fingers. Burnt silk smells like burnt hair. Wool behaves in the same way as silk when put to the fire test, but you aren’t likely to confuse wool and silk – wool is heavier, warmer, rougher, itchier, and just plain woolier than silk.

Synthetic silk imitations made of polyester or nylon will melt as soon as they near the flame. They burn much more readily than silk. As with silk, there will be a black nub at the end of the thread after burning, but this one is hard and you can’t crumble it between your fingers. The strong odor of burnt synthetic filament is not at all like that of burnt silk.

Natural silk vs. synthetics in the fire test. Natural silk won’t flame up, and a burnt bit of fabric will have scorched black fibers that crumble between your fingers. Synthetic imitations will burst into flame and leave behind a hardened black mass that cannot be crumbled between your fingers.

Natural silk (left) will not flame up, and a burnt bit of fabric will have scorched black fibers that crumble between your fingers. Synthetic imitations (right) will burst into flame and leave behind a hardened black mass that cannot be crumbled between your fingers.

Cellulose-based imitation silk: Rayon, cupro, modal, and acetate are common materials for making silk-like fabrics. Betraying their woody origins, they behave like paper when burnt – they burst into flame, the smoke smells like wood smoke or paper smoke, and when extinguished, a fine gray ash remains. Acetate fabrics – pretty, but fragile, silk imitators – can be identified by exposing them to acetone or an acetone-based nail polish remover, which will cause acetate to dissolve.

Types of natural silk

Many people don’t realize that real silk, as rare as it is, actually comes in a number of varieties. Here are some basics to help you orient yourself in our silk selection.

Types of natural silk ordered by moth type and yarn type

Mulberry silk

Mulberry silk is probably what comes to mind first when someone says “silk.” The term “natural silk” is most closely associated with the fiber produced by the mulberry silkworm (Bombyx mori). This is a domesticated moth, bred over thousands of years from a wild species. You may hear mulberry silk referred to as “cultivated silk,” although making such a distinction is a little misleading since practically all varieties of silkworm are products of cultivation. The mulberry silkworm requires a lot of special care – it is fattened on mulberry leaves under very specific climactic conditions and when its time comes it is gently placed, by hand, into a special pupating chamber so that its cocoon will be perfect and symmetrical. Each cocoon is made of a fiber about 1,000 meters long. The fibers are very fine and even in their raw form have the distinct luster of silk.

Mulberry silk accounts for most of sericulture production so the bulk of natural silk on the market is of this type. It is used to make a broad range of silk fabrics. Our article on silk fabric types will tell you more.

Mulberry silk fabrics at Sartor Bohemia

Most silk fabrics at Sartor Bohemia are made of mulberry silk

Wild silk

The mulberry silk moth is not the only creature whose cocoons can be used in textiles. There are other silk moths living in the wild that give us the fabrics known as wild silk. While wild silk has traditionally been held inferior in the West, the opposite is true in India. This is really just a matter of taste. Wild silk is stiffer, more rustic looking, with a slightly muted hue (dyes don’t take as well on it as on mulberry silk), but it’s just as light and airy as any other silk and its untamed, natural appearance lends it an uncommon beauty. The most common types of wild silk are eri silk, muga silk, and tussar silk.

Eri silk

Eri silk is spun from the cocoons of the ailanthus silk moth (Samia cynthia). Produced mainly in Thailand and India, it is one of the highest quality wild silks. The pupa is not killed in manufacturing – cocoons are processed after it has emerged. This has earned it the moniker “peace silk.” It’s also one of the reasons that eri silk is preferred by many, including Buddhist monks.

Tussar silk

Tussar silk (also known as tussah, tassar, tasar, and kosa silk) comes from the cocoons of moths of the genus Antheraea. The natural color of tussar silk is a golden beige, but it can be dyed. Tussar silk is generally left in its raw form, so the fabrics made from it tend to have a crisper hand. In India, tussar is valued for its stiffness (starching is popular there) and is the preferred fabric for making sarees.

Muga silk

Muga silk is produced exclusively in Assam. It has a beautiful golden hue and is held sacred by some. It is the most expensive of the wild silks. Muga is produced by the muga silk moth (Antheraea assamensis). Fabrics from muga silk are lustrous and very durable. Historically they were reserved for use by royalty.

Far less wild silk is produced annually than mulberry silk, so it’s more difficult to come by. Paradoxically it’s also less expensive. To see more of these unconventional fabrics, check out our selection of wild silks.

Wild silk at Sartor Bohemia

Spun silk

Cocoon processing creates waste in the form of extra bits of silk fiber. These remnants are not disposed of but are spun into thread like cotton or wool. The silk yarn that results is used to make spun silk fabrics such as noil and schappe. Spun silk is not as glossy as classic silk, but it has the same wonderful qualities: It’s soft, light, and comfortable and it breathes. It has a rougher appearance and is less fine and delicate, so it’s great for everyday clothing.

Note: Spun silk can be made from any kind of silk waste. It can be made from mulberry silk as well as wild silk.

Spun silk at Sartor Bohemia

Silk dupioni

Dupioni silk is a chapter unto itself. It originates with mulberry silk, because it comes from the mulberry silk moth, but technologically it differs from ordinary silk and is used exclusively to weave a silk specialty fabric called dupioni – it isn’t used for any other types of silk fabric.

Dupioni silk is created when two silkworms spin their cocoons side by side, creating a double cocoon that can’t be unwound without breaking the silk fiber. That means that the silk must be partly spun, resulting in a slightly irregular thread with tiny slubs. From this perspective, dupioni silk is a sort of by-product silk, but it’s actually created intentionally (silkworms are placed into the pupating chambers in pairs to encourage the formation of these lovebird cocoons) because there is a strong demand for dupioni silk. The fabric is popular for its characteristic appearance and brilliant color palette – dupioni silk takes dyes especially well.

Read more about dupioni in our report from our recent visit to a silk reeling mill.

Dupioni silk at Sartor Bohemia

How silk is made

Silk production is a complex and time-consuming process. Silkworms and cocoons require constant care and attention and processing cocoons into thread is a demanding task.

It’s also a fascinating process, and one that we have undertaken to document for you step by step. Join us on our visit to a silk reeling mill, for example, to see how the ultra-fine cocoon fibers are transformed into exquisite, glossy threads.

By the way, did you know that silk cocoons are bought and sold on special trading floors, their prices rising and falling just like stocks on Wall Street? In India these markets are the only legal channel for trading in silk cocoons. The market takes the form of a live auction and can be quite a nail-biter. Curious? Check out our report from a cocoon market.

Silk cocoons on the market await their buyers – a view of the trading hall for mulberry silk cocoons

Sartor visits the cocoon market

History of silk

According ancient legend, silk was discovered by the Chinese princess Hsi Ling Shih who lived around 3000 BCE. She was sitting in her palace garden enjoying a cup of tea one day, when a cocoon fell into her cup. The lady wanted to fish it out, but the cocoon started to unravel into a very fine thread. She immediately understood the potential of her discovery and began to study the life of the silk moth, ultimately becoming the founder of Chinese sericulture.

We’ll never know if there’s any truth to that story, but archeologists have found remnants of processed cocoons, fragments of cloth, and the remains of a weaving loom from a period between 4000 and 3000 BCE. The Chinese guarded the secret of silk production for a very long time, but, still in ancient times, it ultimately leaked to Japan, Korea, and India. Silk was later imported to Europe, Africa, and western Asia as a luxury good – first in a trickle and later in greater volume on the Silk Road. The route led from the Chinese city of Xi’an all the way across Asia to the Mediterranean. The journey took about a year, with caravans conveying not only silk but also perfumes, spices, tea, and porcelain. From Rome, they carried back gold, glasswork, and wine. The Silk Road was vital to the cultural development of the areas through which it passed because aside from goods it carried religious and philosophical ideas as well as scientific knowledge in a number of fields. Sometimes the Silk Road also brought disease, like the dreaded bubonic plague, but that’s another story.

Silk production in imperial China

Silk production in imperial China

There was one thing the caravans were forbidden from carrying off… the secret of how silk is made. China meant business about keeping its monopoly (Europeans were willing to lay out exorbitant sums in gold for their silks) and the export of silkworms or their eggs was strictly forbidden on pain of death. The first to lay hands on the coveted silkworm was the Byzantine emperor Justinian I, who dispatched a couple of monks to smuggle some out. They returned with their contraband in 552 CE and European sericulture was born. It was no great distance from Byzantium to western Europe, northern Africa, and the middle east.

The center of the European silk industry soon settled in Italy, with Lucca, Venice, Florence, and Genoa at its heart. Silk production also flourished in Spain, where looms were kept busy for Muslim rulers in Andalusia and then for Catholic kings in Valencia (which was renowned for its velvet). The silk industry eventually took root in the French city of Lyon, where some original workshops are still in operation today. In the 17th century, a full third of Lyonnais worked in the silk industry. Italian and French silks were of exceptional quality, earning both countries a lasting place in the newly emerging world of high fashion.

The second half of the 19th century brought a blow to the European silk industry, which was decimated by an epidemic that spread among silkworms. This drove up the cost of European silk, which could no longer compete with other products manufactured by its booming textile industries, nor even with imported silks which had been made cheaper by improvements in transport (faster boats, the opening of the Suez Canal).

Several mills in Europe still manufacture luxury silk fabrics today, but the raw material for their production is imported from Asia. The world’s leading producers of silk are now, as in ancient times, China, India and, to a lesser extent, Japan.

Silk in every wardrobe

An absolute classic with a rich history, silk deserves a place in your wardrobe. Silk is a perfect example of slow fashion – it offers quality, beauty, and comfort and it definitely won’t languish, unworn, in the back of your closet until you toss it out without ever putting it on. The selection of silk fabrics is so vast, that it finds its way into an array of garments, from sumptuous eveningwear and bridal fashions, to summer tops, lingerie, and nightwear.

Wedding skirt in natural silk

Full-length wedding skirt in natural silk by Lucie Komarkova

Source: https://www.luciekomarkova.com/p/dlouha-svatebni-sukne

Compared to materials like cotton or rayon, silk is truly ecological. Its production requires neither vast amounts of water nor toxic chemicals. What’s more, it calls for an abundance of live trees for silkworms to feed upon, so silk production means also large, healthy, mulberry orchards.

Have a look at our full selection of silk fabrics. If you need any guidance when making your selection, don’t hesitate to ask… we’re here to help. CONTACT DETAILS

Silk fabrics at Sartor Bohemia

The majority of silk fabrics at Sartor Bohemia are natural mulberry silks