ITR-Labs Textile Research

In this post we would like to explain that there is a connection between the clothes we wear and some skin allergenic reactions .

Allergenic reactions are due to the contact between the skin and some allergenic factors, which, in the case of fabrics, derive from the chemical substances used to dye the textile. Some elements of the so-called disperse dyes’ class are particularly prone to provoke intense allergenic reactions when deeply and long in contact to skin.

Why disperse dyes cause allergic reactions?

Disperse dyes are small molecules: their hydrofobic nature allows them to penetrate into a highly crystalline and hydrofobic fibre and dye it.

As they are small molecules they tend to get out of the fiber; thank to its hydrofobic character the skin in contact to the fabric tends to absorb the dye, especially in those part of body where the rubbing is significant. If the absorbed disperse dye  is one of those classified as “allergenic” it is possible that an allergic reaction will appear on skin. The allergic reaction is more probable if some conditions are present:  sweating, friction, and overweight.

When disperse dyes are used? Fabrics made totally or partially of polyester and acetate are certainly dyed with disperse dyes. Particularly polyester fabrics may have serious problems with color discharging by rubbing or washing, because of an abnormal quantity of oligomers present on the fiber (read more).

What to do to reduce the risk of skin reactions?

In order to avoid some drawbacks from fabrics (allergenic disperse dyes, but not only) you could wear only white or pale coloured fabrics.Anyway always wash your new garments before wearing them!

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Tags: allergenic reactions, disperse dyes, oligomers

Have you ever wondered why white fabrics turn yellow?

The reasons are many but one of them is related to the presence of optical brighteners (OBA’s).
First let’s try to understand what is a optical brightener: it’s a chemical that is applied to a white fabric to make it look even more white … it’s a sort of creator of light. How does it work? The optical brightener is capable of capturing the UV rays that come from sun and it transforms them in visible white light, thanks to an internal conversion of energy known as fluorescence. Then it adds light to light.

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Some type of whitening agent are able to return not only white light but slightly purple – blue light: this is important because most white garments are slightly yellow indeed, due to ageing or staining of the fabric; as purple is complementary to yellow (that is purple and yellow together give a sense of white) the result is a sort of  blinding white.

They are designed to mask yellow or brown tones in the fibers and make the fabric look cleaner and brighter than it would otherwise appear to the naked eye.   In other words, the undesirable color is made invisible to the eye in an “optical manner”. But if the OBA stops to work what does it happen? It happens that the original yellowish note jumps out again.
But why an OBA stop working? Because it’s not so strongly bound to the fabric to resist to any washing condition and also because it can be quite easily degraded. By whom? Sunlight itself, especially if combined with polluting agents. In fact optical brighteners are very sensitive to radiation by sunlight and in the long run they undergo to photochemical degradation,  much more quickly if polluting gases are present in the surrounding atmosphere (an example of polluting gases are nitrogen oxides – NOx – which come from combustion engines or heating systems). They work as catalytic agents in photo-degradation of OBA’s, that is they heavily quicken the rate of the reaction.

NOx  are also involved in another mechanism of yellowing: the so-called phenolic yellowing, never heard about it?

This type of problem is caused by the combination of NOx with phenolic products which could be present in the tissue. These may come from polyethylene bags used to protect clothing, which are often stabilized with antioxidant phenolic products, like BHT (ButylHydroxylToluene). Or they come from lignin of cardboard used to contain garments. Anyway these phenolic products combine in the dark with NOx and give yellow products. This is a serious problem for manufactures but fortunately this type of yellowing is removed simply by washing in water.

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Tags: BHT, FWA, lignin, NOx, OBA, optical brightener, phenolic yellowing, sunlight, white

In the northern part of the Earth winter is approaching and with it rain and snow .

We want to speak today of some concepts related to the ability of the fabric to keep the body dry. In particular we will talk about water-repellent, waterproof and breathable.

WATER REPELLENCY

Not to be confused with the waterproof water repellency is the ability of a fabric to slip away the drops of water that settle onto the material. Normally, the water repellency is evaluated by the spraytest: tissue, placed at 45 °, is bathed in a small shower, and if the fabric is well-protected droplets tend to form balls and slip away, leaving the material completely dry. The values, which sometimes can be read on the labels of technical apparel, are ISO 1 (or AATCC 50) in the worst case and ISO 5 (AATCC 100) for better water repellency.
The most commonly product used for water repellency is TEFLON: it works very well but unfortunately it tends to disappear as a result of repeated washing and abrasion on the fabric.

WATER PROOFNESS

The waterproofness is the ability of a fabric not to enter the water from the outside inwards. The waterproof ability is evaluated through a test known as “water column” that involves exposing the tissue to an increasing hydrostatic pressure and to assess to what pressure (mm column) the first three drops of water come out. The higher the value of column the better the waterproofness. Highly technical products, such as mountain jackets, should have a water column of 10,000 mm; under this value the fabric has not excellent performance.

Some highly technical fabrics may reach to 20,000 mm!

But how do you get a good waterproofness? By applying a coating to the fabric or a membrane.

What is the difference between the two solutions?
The membrane operates mechanically and is something of a dense network that has holes larger than vapour’s molecule but smaller than water’s ones so that the vapour comes out (good breathability) but the water does not enter.

The membrane must be pasted to the fabric, and then often coupled with a further protective material; it’s usually made of precious materials (an example is PTFE-polytetrafluoroethylene- used for the wellknown Gore-Tex);
Coating is a sort of varnishing of the fabric surface and it’s a cheaper solution than the membrane: a layer of a product, normally based on polyurethane, is spread onto the fabric: as you can decide the entity of product deposition you can obtain different effects: the greater is the thickness of the coating the higher is the water repellency but the lower are breathability and abrasion resistance of coated fabric.

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Summing up…

If you want to purchase an excellent technical clothing:

• - the value of water repellency (spray test) should be high, in order to avoid the outer fabric get soaked (anyway you know that the effect is not everlasting)

• - the value of water column should be 10.000 mm at least

• - in addition to water column and spraytest have a look to the seams: they must have a proper taping on the backside, to avoid water crossing through them!

Tags: coating, membrane, polyurethane, PTFE, sprytest, technical clothing, water column, water repellent, waterproof

Wool is a natural fiber obtained from the hair of sheep and certain other animals. The diameter of a wool fiber is about 18-25 microns (consider that a human hair is about 50-100 microns) and when you examine it with a microscope you can appreciate that wool fibre has typical scales along its surface.

Despite their microscopic dimensions (their thickness is less than 1 micron) they are the very responsible of wool felting.

During washing, either machine’s or handwash, wool fibers are stressed by temperature and rubbing and the tiny scales lift up. As the fibres rub heavily against each other they lock down on nearby fibres and they form a tighter and tighter mass. As a result wool fabric felts and shrinks.

Felting is an avoidable process: it can be drastically reduced controlling the temperature of washing (30°C are desirable) and, mainly, the mechanical stress onto the fabric, by choosing a gentle cycle with few agitation. Obviously dryer is normally not to be used with wool fabrics!

“Superwash wool” is a wool that has been treated by a process that smoothes or glues the little scales on the fibre so that they do not lift up. These treated wools can go through both a washer and a dryer. Anyway we suggest you to be very cautious.

Felting is not only an undesirable consequence of washing. Wool felts are the product of  an industrial process based on controlled use of water, steam, mechanical abrasion and drying.

Felts have many important applications, from the automotive industry, to musical instruments, home construction and free time activities.

By the way… Christmas time is coming…wool felt is an excellent material for home made decorations!

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Tags: felt, microscope, shrinkage, wool, wool scales

Recent years have reported a worrying increase in the incidence of skin cancer worldwide. A primary reason for the increased incidence of skin cancers is attributed to stratospheric ozone depletion. Because ozone is a very effective UV-absorber (UV rays can be very dangerous) each one percent decrease in ozone concentration is predicted to increase the rate of skin cancer by two percent to five percent. It is estimated by the United States Environmental Protection Agency that ozone depletion will lead to between three and fifteen million new cases of skin cancer in the United States by the year 2075! Other reasons for the skin cancer diffusion can be traced to lifestyle changes such as excessive exposure to sunlight during leisure activities.

Fortunately we can use our intelligence to continue enjoying sun exposure and meanwhile avoid undesirable effects of irradiation. Apart from  reducing exposure to the sun, the most frequently recommended form of UV protection is the use of sunscreens, hats, and proper selection of clothing.

Garments play an important role in protecting our skin from this threat!

How?

First of all a short examination of UV rays: the ultraviolet radiations can be divided into three regions: UVA (315 to 400 nm), UVB (280 to 315 nm), and UVC (200 to 280 nm). UVC are totally absorbed by the atmosphere and does not reach the earth. UVA cause little visible reaction on the skin while UVB are most responsible for the  development of skin cancers.

Because fabric is composed of fibers that can absorb, reflect or scatter radiant energy, garments have the ability to absorb and/or block most of the incident radiant energy and prevent it from reaching the skin.

However, a fabric’s ability to block UV rays is dependent on several parameters: fiber chemistry, fabric construction (porosity, thickness and weight), UV-absorbers and other finishing chemicals that may have been applied to the textile material.

Fabric construction and UV protection

Porosity, weight, and thickness are the most important parameters under the fabric construction category. Numerous studies have concluded that fabric porosity (openness) is the best predictor of UV transmission through white and undyed fabrics with fiber chemistry coming in second.

Colour and UV protection

The colour of a fabric is a very significant factor in preventing UV radiation transmission through a textile because dyes act as effective UVabsorbers. The studies related to the effect of colour on UV radiation transmission state that, for fabrics of identical weight and construction, darker coloured fabrics are more effective UV absorbers than lighter shades.

Additives and UV protection

Sometimes fabrics have to be treated with additives in order to improve their UV protection abilities. The simplest type of additive, albeit a very effective one, is  the delusterant pigment TiO2 which acts as an UV absorber. Since TiO2 is incorporated during fiber manufacturing the effect is permanent.

The labeling of UV-protective textiles: UPF value has to be declared!

UV protective capabilities of a textile fabric are ranked with UPF value, that is the acronym for Ultraviolet Protection Factor. It’s the ratio of the average effective ultraviolet radiation (UV-R) irradiance transmitted and calculated through air to the average effective ultraviolet radiation (UV-R) irradiance transmitted and calculated through fabric (ref. ASTM D6603).

The higher the UPF value the greater the protection provided:

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When a fabric is declared UV-protective UPF must be declared in order to permit consumers to compare the amount of protection provided by various textiles and purchase the product that best meets their sun protection needs!

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Consider that when skiing or snowboarding  you are typically at 8,000 feet (or even higher!) above sea level. That means you are exposed to 40% more UV radiation and snow can reflect up to 90% of the sun’s UV rays back at you!

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Tags: fabrics, ozone, skin, sun, TiO2, uv protection

Protective clothing is an important part of textiles classified as technical or industrial textiles. They are used principally for their performance or functional characteristics rather than for their aesthetic or decorative feature. Protective clothing is designed to protect the wearer from harsh environmental effects that may result in injuries or death.

We would like to concentrate on one particular aspect of protective clothing: FIRE PROTECTION

Needless to say that fire is charming but it can be very dangerous…

Human tissue (skin) is very sensitive to heat. It is reported that, at 45°C, the sensation of pain is experienced, and at 72°C the skin is completely burnt.

It’s also important to know that the most frequently ignited materials during a fire are the textiles, especially upholstery and furnishings: is terrible to think that  typical textile flame temperatures may range from about 600 to 1.000 °C!

The purpose of fire-protective clothing is to reduce the rate of heating of human skin in order to provide the wearer enough time to react and escape. Under normal conditions, only 3±10 seconds are available for a person to escape from a place of fire with a heat flux of about 130±330 kW/m2.

Protective clothing designed for flame protection must have two functions, i.e., be flame-resistant and form a heat barrier. The latter is a very important factor if the wearer needs to stay near flames for a fairly long time.

Using inherently flame-retardant materials, applying a flame-retardant finish or a combination of these methods are commonly used to make clothing and textiles flame retardant.

An example for a inherently flame-retardant material? Aramid or para-aramid fibres, such as Kevlar (image) and Nomex.

Their name is a shortened form of  “aromatic polyamide” and they are a class of heat-resistant and strong synthetic fibers, characterized by a highly oriented chains.

And now our final practical tip for you…

If a fire occurs in your home and you don’t have a fire blanket you could try to suffocate it using a normal blanket…  But be careful to use wool; that’s because within the area of flammability of all so-called conventional fibres, wool has the highest inherent non-flammability!

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Tags: aramidic fibres, blanket, fire, fire protection, flame retardant, kevlar, nomex, protective clothes, wool

Never happened to notice that your denim pants slowly fade or turn yellow?

The reason is the particular nature of the dye used for denim. Let’s see.

Jeans are usually coloured with indigo, once a natural dye but now mainly synthetic in nature.

Indigo dye is not soluble in water and so it cannot be directly applied to denim. To be dissolved and bounded to the fabric, it must undergo a chemical change (reduction) which converts indigo into soluble “white indigo” (leuco-indigo). When the soaked fabric is removed from the dyebath, the white indigo quickly combines with oxygen in the air and reverts to the insoluble, intensely blue colored indigo.-

Due to the peculiarity of this process a little part of unbounded indigo is normally present on yarns and it can be easily removed from the fabric; this is the reason why fading of denim is unavoidable when you rub it or when you repeatedly wash it.

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But indigo is also involved in turning yellow of denim. This is a process induced mainly by OZONE , a strong oxidizing agent which accumulates in the air as a consequence of pollution.

Ozone degrades the indigo into isatin and anthranillic acid. As the complex of the two products is yellow in colour your jeans acquire a shade of green.

The complex is very soluble in water and green-yellow disappears only with a washing cycle and a slightly less intense blue colour remains on fabric. Unfortunately the whole cycle can repeat many times and the fading of denim can be very considerable.

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Although ozone induced oxidation of indigo is unavoidable and irreversible you can control this process. How?

If you are a manufacturer of denim pay attention to reduce the excessive unbounded indigo deposed on fibres (back staining) and avoid the presence on fabric of not well rinsed chemical products.

Anyway proper storage is also important to control the turning yellow and consequent fading of denim because high levels of humidity as well as long time of exposure to pollution could drastically enhance this problem.

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A little curiosity… the name “jeans” comes from the American strain of the word Genoa (Genes in French), as the Genoese sailors were seen always with pants made with a similar fabric. A fabric with the same characteristics was also manufactured in the city of Nimes, known as “serge de Nimes” contracted then in denim.

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Tags: backstaining, denim, fabric, fading, indigo, isatin, jeans, ozone

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Many people think sweating is only an annoying problem however this is actually not true at all.  Sweating is important for our body because it helps to keep the body’s temperature properly regulated.

But sweating can also cause troubles like unpleasant odors, due to the bacterial growth on skin, and unwanted stains on your clothes, especially under the armpit area! Often these sweat stains are even invisible, and you will notice them only after some time. Generally sweat stains are more visible on whites (they turn yellow), but also dyed fabric are sensitive to contact with sweat.

If sweat isn’t removed properly it could even weaken the fabric by damaging the fibers. Dry cleaning process and heat can get the situation even worse.

Let us tell you why a sweat stain appears….

What causes sweat stains?

First of all sweat is not directly responsible for stains. The real cause is the combination of sweat with some products contained in many deodorants. What products?

The studies behind armpit stains tend to focus on the Aluminum Chloride (or Aluminum salts) contained in many antiperspirant and deodorant products. Aluminum Chloride doesn’t dissolve easily, and when it combines with your sweat, it tends to create acidity (that could cause the colors on your clothes to shift), and it produces a water resistant stain.

How can you prevent armpit stains?

The best way to prevent potential staining is to apply just a thin layer of antiperspirant to your underarms and to allow it to dry thoroughly before putting clothing on. This will prevent the acids and aluminum salts from getting on your clothes.

Before washing clothes you should focus on the armpit area: warm or hot water can ‘set’ the stains by causing a chemical reaction that binds them to the fabric. Pretreating with a stain remover can make the situation worse. Then it is best to wash the stained part with cold water. The cold water will function to neutralize the acids that consume the fabrics. Just soak the armpit part into cold water before you finally wash it.

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Since sweating is unavoidable you only have to use your products properly and  wash your clothes correctly in order to reduce this unpleasant consequence of sweating!

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Tags: aluminum chloride, antiperspirant, armpit, clothes, deodorant, fabric, stains, sweat stains, textile, tips

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What’s better than a fresh laundry that sways and scents the air under a beautiful summer sun?

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Indeed it is known as the sunlight is hygienically beneficial due to its bactericidal action, thanks to UV (ultraviolet) rays which are a natural component of sunlight.

However exposure to sunlight can also cause the change in color of irradiated tissue. Without going into too much scientific aspects (but if you are interested in we can do it) is sufficient to say that the energy of sunlight, when absorbed by dye’s molecules on the fibers, can cause their gradual destruction, so resulting in slow disappearment of the tissue’s color.

If the fabric is dark in color (dark blue, black, dark brown) it requires a longer exposure to cause a discoloration, rather than a pale hue which could require few hours to discolor. Anyway not all colored garments behave in the same way under sunlight exposure… those dyed with better quality products can resist a lot. If the dyes are bad they start to degrade immediately.
These considerations also apply to white fabrics because many of these are actually dyed with an optical brightener (which is a kind of color) that can degrade by irradiation and leave out the yellowish color of the original tissue (essentially white fabrics could turn yellow).

Finally take care of your garments and preserve them from discolouring by avoiding direct sunlight when drying!

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Tags: colour, drying, fabric, laundry, shade, sun, sunlight, ultraviolet radiation, yellow

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”Now that you’ve chosen your piece of clothing let us give you some useful advice before you wear it”

…First of all, never use a dress without washing it, because a new fabric contains many chemicals.
If it loses a lot of color during washing it’s better to do another cycle. You could use some vinegar in water if the fabric is made of polyamide or wool; or  salt (sodium chloride) if you have cotton … perhaps  it will not lose color anymore.

When you dry the clothes never expose them to direct sunlight and if you use tumble dryer be careful not to use cycles too long (high temperature and rubbing are harmful to fabrics).

Ok, we hope you read something new.  But now it’s time to ENJOY your cloth… and your baby! Bye

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Tags: baby, health, tips, washing