How artificial fabrics burn. How to determine the composition of yarn by burning

How to determine the composition of the fabric? This question may arise to you if you have found pieces of fabric that were purchased long ago and forgotten in the closet. In addition, if you often travel and want to buy clothes made from natural fabrics at the Asian market, it makes sense to make sure the seller is honest so as not to pay the price of silk for cheap synthetics.

We will tell you how to determine the composition of a fabric using fire and what else to pay attention to.

Let us remember that the fabric is formed by interlacing the warp and weft threads. When both threads are made of the same fiber, the fabric is homogeneous; otherwise, the fabric will have a mixed composition. There is a laboratory method for checking the composition of fabric, which is based on analyzing the effect of special chemicals on it. We will tell you about a simple and accessible method at home, which is based on the different reactions of the material to fire.

You will need a small piece of fabric or at least a few threads. If you want to check the fabric composition already finished product, You can pull a few threads out of the seam allowances. We bring to your attention a table in which you will see how different fabrics react to flame.

Results

In conclusion, we would like to add a few more signs by which you can determine the composition of the fabric.

Natural cotton wrinkles a lot, it is warm in the hand
Natural linen often consists of threads of different thicknesses; it wrinkles and feels rather cool to the touch.
Natural wool hardly wrinkles
Natural silk has a beautiful shine, does not wrinkle much and is warm to the touch.
Viscose drapes well and wrinkles strongly, this material is soft and pleasant to the touch
Synthetics are easily electrified, the material is cold to the touch and often a little rough.

There are a number of ways. Of course, the most reliable method is the laboratory method. It includes microscopic and chemical analyses. However, most often we have to resort to the organic method - determining the fabric by eye, touch, crumpling, stretching, tearing, burning.

By appearance linen fabric more shiny, cotton - matte.

The threads of the cotton fabric are even, while the threads of the linen fabric are thickened in places.

To the touch: linen fabric is stiffer, and when applied to a naked body it gives a feeling of cold.

For crumpling: linen fabric produces stiff folds that are difficult to straighten out. Linen fabric has almost no stretch either in the warp or in the weft, while cotton fabric stretches in the weft.

For thread break: Linen will have pointed ends, while cotton fabric will have fluffy and smooth ends.

For combustion: Linen fabric gives off almost no odor, and when cotton fabric burns, a sharp fire and acrid smoke are released.

In the same way, one can unmistakably distinguish natural silk from artificial And wool from wool mixture and mixed fabrics.

Approximately: artificial silk has a sharp metallic sheen, while natural silk has a soft matte finish.

To the touch: artificial silk is hard, while natural silk is soft. Wool fabrics Depending on the nature of the fiber and its structure, it can be very soft, semi-coarse or coarse.

For crumpling: artificial silk produces a stiff fold that does not straighten out easily. Wool fabrics are the most resilient and elastic. Pure wool fabrics are soft and, once wrinkled, straighten out slowly and completely. Semi-coarse and coarse pure wool fabrics - after crumpling, they give quick and sharp straightening.

To break: natural silk breaks with difficulty, but artificial silk breaks easily, especially when moistened, when it loses up to 70% of its strength. When a thread of artificial silk breaks, it crumbles into separate fibers, while threads of natural silk break off evenly, without crumbling. The wool thread does not break immediately, but first stretches significantly.

For combustion: natural silk is sintered into a ball and goes out, while artificial silk burns out completely. When the wool burns, it sticks together into a ball, goes out, and smells like burnt horn. If the light runs along the thread with the same smell of horn, this is a clear sign of the presence of plant fibers or artificial silk. If the thread burns down to 1-2 cm and then goes out, also emitting a characteristic odor, then the presence of plant fibers or artificial silk makes up a significant percentage.

Wool blends for crushing and stretching do not give the same indicators as those inherent in fabrics made from pure wool.

Depends on the fibrous composition appearance, tissue elasticity, cutting resistance, fraying, extensibility, ability to iron and pull back, choice of WTO mode.

Depending on the fibrous composition, fabrics are divided into homogeneous, heterogeneous, mixed and mixed-heterogeneous.

HOMOGENEOUS fabrics consist of the same fibers, for example wool, cotton, silk, etc.

HETEROGENEOUS fabrics consist of thread systems of different types of fiber, for example, warp - cotton, weft-wool; warp - viscose, weft - acetate.

MIXED fabrics are fabrics that contain different fibers in the warp and weft, mixed during the spinning process. For example, the warp and weft are wool with lavsan. Mixed fabrics include fabrics made from twisted non-uniform threads.

MIXED-HONOGENEOUS - these are fabrics that have one system of threads that is uniform, and the second from a mixture of fibers. For example, the warp is cotton, and the weft is a mixture of wool with staple viscose fiber. Based on the presence of more valuable fiber, heterogeneous, mixed and mixed-heterogeneous fabrics are usually called half-wool, half-linen, half-silk. Half-silk fabrics usually have a silk warp and a cotton weft. Pure wool fabrics can contain up to 10% chemical fibers.

DETERMINATION OF FIBROUS COMPOSITION OF TISSUE

You can determine the composition of the tissue using the senses: touch, vision, smell in the following sequence:

By appearance
Touch and wrinkleability
By type of warp and weft threads
According to the nature of fiber combustion

When determining the fiber composition, first of all, you need to pay attention to the color, gloss, thickness, and density of the fabric. Then work on creasing: gather the fabric into folds and squeeze it tightly in your fist, after 30 seconds release it and smooth it with your hand. Next, consider the warp and weft threads. Each thread must be examined separately. Then trace the combustion pattern of the fibers. Burning tissue with an “angle” leads to erroneous results.

Signs of determining the composition by appearance:

Cotton fabrics are usually thinner than linen; cotton gives them a special matte finish, while linen fabrics have a shine. Linen fabrics are often natural color: severe linen fabrics have a grayish or greenish tint. Severe cotton fabrics have a yellowish tint.

Woolen fabrics are recognized by their woolly surface, piled in clothed fabrics and with an open weaving pattern in combed fabrics; The surface of fine cloth fabrics is smooth, while coarse hairs are visible on coarse cloth fabrics. Wool-blend fabrics mixed with cotton are characterized by some fading.

Fabrics made from natural silk are easily recognized by their thin thickness, smooth surface and soft, deep shine.

Based on the nature of creasing and the feel of fabrics, they are determined as follows:

Linen always gives the impression of coldness and rigidity to the touch, cotton - softness and warmth; Linen fabrics, as a rule, are heavier than cotton and have almost no stretch either along the warp or weft.

Pure wool fabrics, when crumpled, either do not form wrinkles, or wrinkles easily disappear; on fabrics mixed with viscose or staple fiber, angular folds remain that do not disappear or disappear slowly.

Fabrics made from natural silk are light, soft to the touch and wrinkle relatively little; artificial silk fabrics are heavier, harsh to the touch and, when crumpled, leave folds that are difficult to straighten out.

To determine the composition of the fabric by the type of warp and weft threads, you need to remove 2-3 threads from each system, put them side by side and compare the appearance. If the yarn is twisted, you need to unwind it into separate threads and look through each thread.

Wool is recognized by its peculiar crimp and slight sheen; cotton by its matte, thin, short fibers; staple fiber by its thin, longer, non-crimped fibers with increased shine.

Determination of the fibrous composition by the nature of the rupture of the warp and weft threads:

When a cotton thread breaks, a fluff of short, very thin fibers forms at its end; at the end of a torn linen thread, a tassel is formed from straight, longer, coarser fibers of unequal thickness.

The wool fibers at the broken end of the yarn are recognized by the presence of crimp; if the yarn is mixed (with a mixture of cotton or staple), the cotton differs in its short, thin matte fibers, the staple fibers are long, shiny, as if flaccid.

When a natural silk thread breaks, the individual fibers remain connected, while in threads made from artificial and synthetic fibers, especially with a slight twist, the fibers at the end scatter, forming a fluffy tassel that “sticks to the fingers.”

The strength of natural silk does not change after soaking, the strength of viscose and copper-ammonium fibers after soaking decreases by 50%, and the strength of acetate decreases by 30%.

By the nature of the burning of fibers, the fibrous composition of fabrics can be determined quite accurately:

Black yarn sinteres in the flame, but does not burn when removed from the flame. A black cake forms at the end of the thread. The smell of burnt feathers or horn. If wool yarn contains 10% plant impurities, a luminous ember forms behind the sintered ball, which quickly goes out, leaving a layer of gray ash. If the yarn contains 15-20% impurities, then 1.5-2 cm of thread burns, then the flame goes out. If the yarn contains more than 25% of plant impurities, then the entire thread burns and loose gray ash remains. If wool yarn contains nitron or lavsan, then it burns with a yellow, smoky flame, forming a hard skeleton of the thread, the smell of a feather. If the yarn contains up to 10% nylon, it burns like pure wool, but a ball remains at the end, which does not rub well.
Cotton fibers burn with a yellow flame and burn completely, forming gray ash. The smell of burnt paper.
Linen burns just like cotton.
Natural silk burns similarly to wool.
Rayon fibers burn faster than cotton.
Acetate fiber burns quickly with a yellow flame, leaving a melted ball at the end.
Nylon fibers burn with a bluish flame, forming a brown melted ball.
Lavsan melts, then slowly burns with a yellow, smoky flame.
Nitron, acrylic (polyacrylonitrile fibers) melt and burn with a yellow flame with flashes.

In the laboratory method of determining the fibrous composition of tissues, microscopes and chemical reagents are used. To determine the composition using this method, you need to have a good knowledge of the structure of the fibers and their chemical properties. The laboratory method gives a more accurate result than the organoleptic one, but in practice it is more often used last method as more accessible.

Today we have laboratory work. Today we are setting fire to yarn. Not for the sake of self-indulgence, but for the sake of determining its composition. Experts call this process an organoleptic method for recognizing fiber by burning.

For what? Many years ago, you bought yarn, knitted something from it, and put the rest in long-term storage, forgetting to sign it. Or someone gave you yarn without labels, and you don’t know its composition. Or there may be some other situation, and the composition is also unknown. Is it necessary to at least roughly know what kind of animal is in your hands?

Is it necessary to know the composition of the yarn? Isn't it enough to visually and tactilely examine the thread and knit the product based on the thickness and color of the thread? No. The color and thickness are very insufficient.

Imagine, without knowing the composition of the yarn, you knitted a product, washed it and... The product stretched greatly in breadth or shrinked greatly. And if your summer T-shirt after washing is very fluffy and resembles a shawl. Or your jumper has been welded so that its fabric has lost its pattern and resembles felt boots. These are not all the troubles that can happen due to a lack of understanding, what kind of yarn lies in front of you?

I suggest you at least roughly determine what you have to work with. Let's set fire to pieces of yarn. I remember we did this at school during home economics lessons, but there we burned fabric. The essence does not change today, since fabric and yarn are made in production from the same materials. So.

We take about 10 cm of yarn and set one end on fire. We look at how quickly the thread burns, what the color of the flame is and the nature of the combustion, pay attention to the smoke, if there is any. As soon as half of the thread has burned, we blow it out sharply and look at the result. As soon as everything has cooled down, we try to rub the combustion product with our fingers, that is, what remains after combustion.

Ball 1. The thread is badly eaten by moths. You don't have to burn it. The thread is natural, wool, quite edible and even very tasty. If the moth that found this ball died of gluttony without having time to leave offspring, you will not find it. Set fire to the thread. Wool doesn't melt. It burns slowly, the flame is weak and flickering, and the smoke smells like burnt feathers or hair. During combustion, black or dark brown ash appears in grains. The cooled grains crumble into powder. Chemists claim that wool is resistant to mineral acids, and is destroyed in hot sulfuric acid and weak alkali solutions.

Tangle 2. Silk. This is an animal fiber. It burns like wool, it smells the same, and when burned, its ash also forms in the form of a black ball, which also crumbles into powder. We are talking about natural silk. Rayon is a synthetic.

Tangle 3. Viscose. This fiber has a silky shine. Burns quickly and brightly, does not melt, smells of burnt wood or paper, leaves a light ash. Viscose dissolves in hot dilute and cold concentrated acids. Concentrated alkali solutions cause it to swell.

Tangle 4. Cotton. This is a plant fiber. It ignites easily, burns quickly with a bright yellow flame and has a burnt paper smell. When burned, it leaves a white-gray ash. Cotton is not very resistant to chemicals and minerals, mineral acids, but is resistant to alkalis.

Tangle 5. Linen. This is also a plant fiber, and when burned it behaves in the same way as cotton, only it extinguishes faster and smolders poorly.

Tangle 6. Synthetics. There are a lot of synthetic fibers in production, and they all behave differently. Acrylic, nitron, acetate, nylon, nylon, polyester, spandex and a bunch of others with unearthly names - these are all synthetics. But they have a common property - they do not burn and do not leave ashes. They melt, leaving a dense ball. This is why firefighters and the Ministry of Emergency Situations do not recommend synthetic clothing. If the flame from natural clothing can be knocked down or extinguished, then the remains of the melting synthetic clothing stick to the body and leave burns. In addition, the smoke that is produced during combustion, that is, during melting, is often very poisonous. That is why in case of fires in large entertainment venues, where everything is decorated with plastic, people die not from fire, but from poisoning and suffocation. But not all synthetics stink so bad. For example, acrylic or melting reminds the smell of fish, acetate smells like vinegar and paper, nylon smells like celery. By the way, the color of the melted synthetic balls can also be different, creamy, bluish, and black. When hardened, these balls do not crumble into ashes, which distinguishes synthetic fibers from natural ones.

To summarize, we can say that fibers of plant origin (cotton, flax and everything that during their life represents grass and trees) when burned smell like burnt paper or wood, fibers of animal origin (wool, silk and everything that walks and eats during life) and makes sounds) when burning they smell like burnt feathers and hair, and fibers of synthetic origin, like all chemicals, can smell like anything and even stink like anything. The ash of fibers of plant and animal origin crumbles, and in most cases artificial ash is sintered into hard balls. I repeat: in most cases. This means that scientists do not stop there and the products of their creativity may soon give natural ones a head start, if they have not already.

Attention! These descriptions only apply to 100% yarn compositions. If the thread is a mixture of different fibers, it may be difficult to determine them, and even more so in their percentage composition. But here too you can fight.

Try to take the thread apart into pieces. If the thread is untwisted, it is often seen that it is assembled from different fibers. Using tweezers, sort these fibers into different piles, estimate the percentage and burn each pile separately, forming a ball from each pile or even twisting the threads.

Stop! They forgot about the most important thing! Safety precautions! Before you start experimenting, protect your hair with a headscarf and prepare the room, remove extraneous odors, and eliminate drafts. After burning one thread, ventilate the room, burn the second thread and ventilate the room again. Be sure to place something non-flammable under the material you are burning. Let it be a plate, a baking sheet from the oven, or a simple sheet of foil from a chocolate bar. It is not recommended to use matches; they are wooden, and their smell will overwhelm the smell of burnt thread and interfere with the experiment. A candle or a simple lighter will help you. Be sure to have water ready so that you can put out a fire that has gotten out of control in time. Remember that some fibers do not ignite immediately, but once ignited, they become excited and do not want to go out.

You can, of course, test the fibers chemically. For example, in nitric acid (HNO 3) cotton will dissolve and wool will turn yellow. And if you immerse cotton in a 10% solution of caustic soda (NaOH), it will swell, but wool will simply dissolve.

But you are unlikely to do such experiments at home, it is unsafe, and the necessary solutions may simply not be available at home.

The easiest way to determine what fiber a purchased fabric is made from is to use a combustion test. Natural fibers burn and char, turning into ash. Synthetic ones melt, leaving a hard lump. Cotton and linen fabrics (from plant fibers), as well as wool and silk (from animal fibers) burn equally.

Acetate and acrylic fabrics

They burn and melt in the flame and outside it, when they have already been removed from the flame. After burning, a solid lump remains. Acetate fabric can be easily identified by placing a piece of it in nail polish remover: the acetate will dissolve in it.

Polyester, nylon and other synthetic materials

They do not burn, but only melt in the flame or a short time after removing it with a chemical smell, leaving a hard lump.

Wool and silk

They burn slowly, charring and curling into rings. Sometimes they only burn while in the flame. They smell strongly and not very pleasantly, like burnt hair or feathers, and leave brittle ash.

Cotton and linen

They burn quickly followed by a glow. When burned, they smell like burnt paper, forming soft gray ash.