glossary

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Abrasion Resistance open

The professional’s definition of abrasion resistance is the ability of a material to withstand mechanical action such as scratching or rubbing. Having an abrasion resistant material means it will simply last and look better for longer. A Dartex fabric may be bumped, scraped, and scratched so we can add some tougher polymers turning a delicate textile into a tough cookie. We test our fabrics for abrasion using the British Standard BS EN ISO 5470-2 also known as the Martindale Abrasion test. Here samples are fixed and rubbed with an abradant in a cycle. We don’t stop there we further test for water penetration resistance.

Accelerated Testing open

Accelerated testing is a test performed on materials aimed to speed up failures by the same processes the material would experience when in use. At Dartex we use accelerated testing to see how long our fabrics are likely to last when they get to work. Our quality technicians refer to the British Standard ISO 1419:1995. Here the material is placed in a high temperature and humidity environment, this is why the method is also known as the tropical aging or jungle test (I hope they take their mozzy spray!). Each time the temperature is increased by 10⁰C the rate of aging doubles. One day at 70⁰C is the equivalent of 28 days, so 12 days is same as one year under normal conditions! The reaction we are encouraging here is hydrolysis of the polyurethane which happens gradually over time.

Adhesion of Coating open

The adhesion of coating is the strength of the polyurethane bond to the textile. The Dartex quality technicians test adhesion of coating on our materials by peel bond strength. We mechanically strip the polyurethane from the textile. Newtons per 50 mm is our unit of measure and each fabric has its own minimal specified bond strength. This is a standard quality control test performed on all Dartex coated textiles, it is essential for us to know we are producing quality and this test gives Dartex and you that reassurance.

Air Permeability open

A brain boxes definition of air permeability is the ability of a material to allow air flow through it. Our Dartex health care products are not air permeable because where air can flow water is sure to try and follow. Other unwanted bits and pieces, maybe even pathogens might also try to sneak through. Dartex can test for air permeability, we use the standard ASTM D737-96.

Anti-microbial Activity open

When something has antimicrobial activity it can kill or inhibit the growth of microorganisms such as bacteria and fungi. Dartex test our products for antimicrobial and antifungal properties in accredited microbiology labs. These tests are particularly important for the Silver3 range and fungal protection additives performance for all products. This ensures/validates our material for a long life and lifelong performance.

Anti-pill Finish open

An Anti-pilling finish stops pilling, us common folk call this bobbling, which makes the fabric look and feel quite unpleasant. Pilling is associated with spun yarn fabrics, especially when they contain synthetics. Pilling is caused by rubbing on the fabric breaking the yarn and making those irritating little balls of fluff.

Bacteria open

Bacteria, germs or bugs are living microscopic microorganisms just micrometres in length with a variety of shapes such as spheres, rods and spirals. They belong to a class of cells known as the prokaryotes predating cells like ours. They are practically everywhere! On and in our bodies, we have ten times more of their cells than our own! In favourable conditions they can multiply rapidly with numbers doubling in 20 minutes and once inside the body, pathogenic bacteria release poisons or toxins that make us feel ill. Bacteria are highly adaptive capable of changing their genes, a feature responsible for antibiotic resistant bacteria like MRSA.

Fungi are also living microscopic microorganisms micrometres in length and can exist as yeasts, moulds and mushrooms. They belong to the same cell class as our own, eukaryotes meaning they are far more advanced than bacteria. Fungi are widely distributed spreading by the production and shedding of spores. They can colonise our body living on the skin and internally, Candida albicans being a common member of the human flora. Fungi can also be very pathogenic breaking down our tissue causing serious health problems.

Biocompatibility open

Biocompatibility is the extent in which foreign material can be in contact with an organism/living thing without causing harm. Dartex knows that many of our products will contact the skin so we make sure they’ll do you no harm and if you’re making a medical device it’s a regulatory requirement. We test extensively for biocompatibility using ISO 10993 for example cytotoxicity. This is important to ensure no adverse reactions happen by the presence of a Dartex fabric and we are proud to say we have had no reported incidences. All our products are latex free and many are Oeko-tex 100 product class II certified.

Breaking Strength open

Testing for breaking strength literally pulls our material to the limit! Breaking strength is the maximum force recorded when stretching a test sample to breaking point. As always there is more than one way to measure this property. In the USA they prefer the Grab method, whilst in Europe we tend to use the Strip method. The strip method stretches the whole sample width and the grab method stretches a central section of a sample. By knowing the physical boundaries of a fabric you can understand how it will perform in use. Knowledge is power after all!

Brushed Fabric open

Brushed fabric is a material that has been mechanically brushed to raise fibres, making it all furry with a softer look and feel. Natural material such as wool and synthetic fabrics like polyester can be brushed creating flannel the cowboy’s favourite! Brushed fabrics are generally used for clothing and bedding.

Bursting Strength open

Bursting strength is the pressure when a material will burst under stress from all directions. The Dartex quality technicians can test our coated and uncoated materials for their bust strength. This tells us the forces our fabrics can withstand making sure they can do their job and are top quality. We follow the British Standard BS EN ISO 12332:1999 which involves pushing a steel ball through the material. The ball moves at a fixed speed until the fabric is popped, it’s quite fun to watch actually!

Coating Methods open

Dartex knows there are other alternative coating methods, we did our homework and we feel we have chosen the best one for quality healthcare products.

Transfer Coating:

In transfer coating the polymer is layered onto a release surface producing a uniform film, then the substrate is adhered to this layer. The fabric structure remains free to stretch and recover with the same drape as the uncoated fabric. A wider variety of substrates can be used as the problem of polymers passing through the fabric in direct coating is eliminated.

Direct Coating:

In direct coating the polymer is applied directly to the fabric. The fabric must be dense enough to prevent the flow of polymer through, limiting the substrate range to mainly woven fabrics. Direct coating could be described as buttering toast where the polymer glues the fabric together reducing consistency, stretch and waterproof abilities.

Transfer and Direct Coating are the two principle methods of coating fabrics however, the method in which a coating is applied can be altered a tad.

Knife over roller: The Dartex Way!

Knife over air:

Gravure Coating:

Reverse Roll:

Hot Melt Web:

Myer Bar:

Slot Extrusion:

Immersion/ Dip Coating:

Curtain:

Spray:

Scatter:

Gravure Coating: This uses an engraved roller turning into a coating bath which fills the engraved pattern with the coating material. The coating is deposited onto the fabric as it is passed between the Engraved Roller and a Pressure Roller. Excess coating material is removed by a Doctor Blade. This method produces variability and often discontinuous coating.

Composition open

Composition is what a mixture is made up of; its ingredients. Composition tests are available for our fabrics looking at their % by weight.

Cotton Fabric open

Cotton is a soft and very fluffy natural fibre which grows in bolls around the seeds of cotton plants to help the seeds spread. Dartex likes cotton for its soft feel, light weight, flame retardant performance and moisture management. We can coat FR treated cotton for clothes to healthcare products.

Course open

A fabric course is a row of yarn loops running across the fabric width of the fabric. Course is the opposite of wales!

Decitex open

Decitex (dtex) is a part of the metric tex system. Tex is a unit of measurement for the linear mass in grams per one kilometre of fibres, filaments, slivers or yarns, quite something to get your head round. Decitex is the most commonly used unit which is the fiber mass in grams per 10,000 meters. Denier the mass in grams per 9,000 meters remains more common in the United States and United Kingdom, a term you’re more likely to hear on the hosiery aisle.

Dimensional Stability open

Dimensional stability is a material’s ability to keep its shape after being placed under a particular condition. The Dartex dimensional stability testing is usually a wash test. We check for fabric shrinkage by comparing the size of the washed fabric to its original size. Dartex fabrics have increased dimensional stability as the coating holds everything in place.. We don’t want that “shrinking feeling”.

Double Coated open

The Dartex lamination line produces our double coated products. This is simply when a second coat is applied to the uncoated fabric side. The second layer in a mattress cover for example gives that little more security, durability, stretch control or water protection. Think of it as our extra safety net to guarantee reliable performance.

Dry Cleaning open

All of our Dartex fabrics are dry clean compatible which may be required for the more delicate textiles such as wool. The dry clean ability gives you further cleaning options however, most products are machine washable so a dry clean may be used as a rare treat!

Dyed Fabrics open

Fabric can be dyed, scoured or printed and Dartex works with them all. Dying adds colour to the material using special chemicals. Scouring fabrics intensively washes the textiles to remove any impurities such as oils and dirt making the fabric all nice and clean. Scouring is normally done to prepare the fabric for dying or printing but plain old scoured fabric can still be used as it is. Printing fabrics gives colour, patterns or text again using dyes or pigments. Many printing methods exist such as rotary screen printing, heat transfer printing and block printing exist. Printing or dying your fabric before coating can add vibrancy, prevent seams showing or allow complex designs, messages or images to appear on your fabric.

Elastane open

Elastane is an intelligent man-made fiber formed from polyurethane-polyurea copolymer. Elastane is known for its exceptional elasticity and are normally incorporated with other yarns such as cotton or polyester to give that extra stretch! Elastane is also known commercially as spandex and lycra, great for working out! Dartex can coat fabrics containing elastane for more specialised healthcare equipment which need that touch more spring.

Electrical Resistance open

Your old physics teacher would define electrical resistance as the opposition an electrical current meets when it flows through an element and electrical conductance is the ease a current can flow through an element. Electrical resistance is measured in ohms (Ω) and conductance in siemens (S) using the metric system. Dartex can create conductive fabrics with an electrical resistance between x103 to x106 ohms per meter square. The trick is to include a conductive material that creates a path for the charge to flow along. Conductive material is great for the surgery environment protecting the fancy expensive equipment from static charges. Dartex tests our materials resistance following the British Standard BS 2050, measuring the resistance between several points.

Embossing open

Embossing is a process that creates a 3D texture or design in a material by normally using heat and pressure. Dartex can emboss using the same principles however we can also use our paper on the coating line to leave a textured finish. Embossing polymers can give a faux leather effect or create patterns on the surface which look and feel great.

Examination open

At Dartex we take quality very seriously so every metre of every roll of fabric is checked and examined. We have a fine eye for detail looking for the tiniest mistakes and faults before it’s shipped out. Our examination stage adds that extra check point to minimise our customers receiving anything they shouldn’t keeping everybody much happier.

Flex Resistance and Flex Testing open

Flex resistance is a material’s ability to withstand bending stress. Dartex can produce lots of flex resistant materials which can bend in every direction again and again without the polyurethane showing its age! This means that the material can conform to complicated shapes without any problems and the fabric flexes its muscles in use. The Dartex quality technicians complete flex tests on our products using any of these: • Schildknecht method which compresses and relaxing the fabric (BS EN ISO 7854: 1997), • SATRA/VAMP method compressing and relaxing the fabric with a downwards crease (BS EN ISO 7854: 1997) • Crumple/Flex method simultaneously twisting and compressing the fabric (BS EN ISO 7854: 1997). They are the limbo champions of the fabric world!

FR Halogens open

Our clever people at Dartex can incorporate halogens into our products to give you flame retardant materials for better health and safety. Halogens are a very reactive group on the periodic table and this property makes them pretty useful to stop fires. Under high temperature the coated fabric releases the halogens and they get to work by reacting with potential fire accelerants rendering them harmless.

The Dartex scientists know that halogens aren’t the friendliest for our planet so we have also come up with a really effective and tough halogen free flame retardant MelaphosFR.

 

 

Fungi open

Bacteria, germs or bugs are living microscopic microorganisms just micrometres in length with a variety of shapes such as spheres, rods and spirals. They belong to a class of cells known as the prokaryotes predating cells like ours. They are practically everywhere! On and in our bodies, we have ten times more of their cells than our own! In favourable conditions they can multiply rapidly with numbers doubling in 20 minutes and once inside the body, pathogenic bacteria release poisons or toxins that make us feel ill. Bacteria are highly adaptive capable of changing their genes, a feature responsible for antibiotic resistant bacteria like MRSA.

Fungi are also living microscopic microorganisms micrometres in length and can exist as yeasts, moulds and mushrooms. They belong to the same cell class as our own, eukaryotes meaning they are far more advanced than bacteria. Fungi are widely distributed spreading by the production and shedding of spores. They can colonise our body living on the skin and internally, Candida albicans being a common member of the human flora. Fungi can also be very pathogenic breaking down our tissue causing serious health problems.

Gloss Level open

Gloss level is the finish we can give our fabrics. We can make them super matt or give them extra shine, we could even apply a textured finish and this is all possible because of Dartex uses the transfer coating process.

Guarantee open

All of Dartex products come with a guarantee. We like to give you a minimum 12 months guarantee for your protection usually starting from when the material has been transformed into the final product. This means that after a year the fabric remains in spec. That isn’t the case with everyone else so it is worth checking the small print. The length of the guarantee however does depend on a number of terms and conditions such as the product type and its end use.

High Visibility open

High visibility is the capability of being seen easily and Dartex does this by colour. We have a range of neon colours which are shade checked to, this builds continuity so you’ll always be spotted! The high visibility is particularly useful for outdoor and security clothing where being seen keeps you safe.

Hydrolysis Resistance open

The Dartex scientists describe hydrolysis as the reaction which breaks down polyurethane and we want to keep it at bay. The long chains of polyurethane are broken up into smaller pieces just like diced spaghetti losing contact points between the polymers. The coating will break down, no longer keeping the liquids out and the result is “strikethrough”, letting all sorts of “nasties “into the mattress. The Dartex quality technicians test for hydrolysis in the accelerated aging tests using heat and humidity to break down the polymer.

Hydrostatic Head open

Hydrostatic Head is the measure of water pressure that a fabric can withstand. The water pressure is increased on one side of the material to greater than 100kpa, that’s about half the pressure of your average car tyre!

Hydrostatic Head after Cleaning open

Our wipe clean products need to be tested to ensure they preform after every wipe and wash! We expose our wipe clean range to cleaning agents such as alcohol and chlorine to simulate the conditions a Dartex fabric may meet and to push the performance boundaries. To make sure cleaning keeps the fabric in tip top condition we test for water penetration afterwards using a hydrostatic head. To be really sure we sometimes stretch it, flex it and abrade it.

Imperial/ US Customary Units open

Imperial units or the United States customary units are systems of measurements derived from the British Imperial system through the evolution of local units over the centuries.

Knitted Fabric open

Knitted fabrics are thread or yarn converted into cloth. They are one of three major fabric groups along with woven and nonwoven material. The structure created is a series of interlocking loops linking left, right, above and below. The two basic types of knitted fabrics are warp knit and weft knit. Dartex uses a lot of knitted fabrics due to their affective stretch and recovery properties.

Knitting Gauge open

Knitting gauge refers to the number of stitches per inch. The gauge can be measured by counting the number of stitches for hand knitting or the number of needles for a knitting machine over a few inches then by dividing the number of inches in the width of the sample. That wasn’t too bad.

Ladder Resistant Fabric open

Ladder Resistant Fabrics are materials which are resistant to runs or ladders, the name pretty much explains it all. A ladder in a pair of tights is probably the best example of a run. All warp knit fabrics are resistant to runs more so than weft knit and with the addition of a Dartex polyurethane coat the chances of a ladder are very slim.

Light Fastness open

Light fastness is the amount of change in colour caused by light. Dartex have a range of particularly light fast fabrics (the endurance range) resisting colour change on light exposure. The colours stay bright and don’t fade away.

Mean Mass open

Mean mass in Dartex is the average weight of sections across the width of the fabric. Weights may fluctuate across the fabric so Dartex likes to check you’re getting the right quality. We have set minimum weight requirement for our products. This is a standard quality control test performed on all Dartex fabrics. Unlike most of us our fabrics always keep their target weight. Jammy little …….

Melaphos open

The Dartex development team has cunningly created a clever halogen free flame retardant MelaphosFR. Loads of our products can use the MelaphosFR system to keep you fire safe without the use of environmentally unfriendly halogens. All our MelaphosFR materials behave as normal unlike other halogen free flame retardants so you never have to compromise performance. MelaphosFR is patented so you can only get this from us!

Metric/SI units open

The metric system or International System of Units (abbreviated SI from French: Système international d'unités) is a system of units of measurement devised around seven base units and the number ten.

 

Micro Fleece open

Micro fleece is a fuzzy insulating man-made fabric created from Polyethylene terephthalate (PET), polyester to you and me, or other synthetic fibers. Micro fleece has some of wool’s finest qualities but weighs a fraction of the lightest available woollens making it a pretty good alternative. Micro fleece also known as polar fleece or simply fleece is used in winter clothes and bedding keeping you all snug and warm for when the nights draw in.

Modacrylic open

Modacrylic is a carbon based man-made copolymer linked with multiple cyanoethane groups forming the fabric fibers, some quite big words there! Modacrylics are incorporated with other fabrics to change their performance, usually for flame resistance. Dartex uses modacrylic incorporated fabrics for the Melaphos ranges for this very purpose. Modacrylic also provides enhanced shape retention, chemical resistance and strength over standard acrylic.

Moisture Vapour Permeability open

Water vapour permeability is the movement of water vapour molecules through a material, this material however is impermeable to liquid water. Sometimes this is called breathability which can be confusing as air has nothing to do with it!

The water vapour can travel in either direction depending on the humidity each side of the material. The molecules will move from the higher humidity to the lower as a natural instinct. A healthy human body loses around 450-750g/m2/day of water vapour so interference with this loss would make things pretty uncomfortable, so we need a fabric that works alongside the body that’s breathable.

To make something ‘breathe’ we could make a micro-porous material using special polymers creating tiny holes too small to let liquid water pass through. These materials however tend to damage easily and potentially anything small enough to fit through these holes will try to sneak through like a virus.

Hydrophilic (meaning water attracting) materials such as polyurethane can attract water molecules and transmit them through the polymer coat. There’s no holes so it remains tough and completely impermeable to liquid water, along with everything else, pretty clever stuff!  This makes polyurethane a great choice for close skin contact and for places microbes maybe hanging around waiting to cause trouble.

There’s loads of ways of measuring water vapour permeability but to make it even more annoying you can’t compare products that have been tested using different methods. A moisture vapour permeability figure means nothing unless you know exactly which test method was used. Each method places the fabric under different conditions and some of these conditions favour the transfer of water vapour more than others.

Here is a list of a few tests used to measure water vapour permeability:

  • The index method BS 7209:1990 aka BS3424 (37) 
  • ASTM E96
  • The Hohenstein sweating guarded hot plate ISO 11092
  • Payne Cup ASTM D 1653

Here at Dartex we use the ‘BS 7209:1990’ aka BS3424 (37) as our main test, and sometimes use the Payne Cup ASTM D 1653 test, although this is much less common.

Polyamide open

Polyamide is a man-made polymer created from monomers of amides linked by peptide bonds, quite a chemistry lesson! Polyamide is also found in natural fibres such as wool and silk. Polyamide in its fabric form is commonly known as nylon. Nylon is highly durable, abrasion, chemical and biologically resistant making it very useful for those tougher jobs.

Polycarbonate PU open

The Science Lesson Our scientists say The Dartex scientists see polycarbonate polyurethane as the ‘super cars’ of the polyurethane family containing all the features of standard polyurethane along with increased strength and chemical resistance! Take your pick of jobs for this polymer! The science lesson: You remember how the polyurethane was made with a reaction between and isocyanate and a polyol. Well this is just the same but the polyol has polycarbonate groups in it. They are like the diamonds in a chain of rhinestones.

Polyester open

Polyester is a cleverly engineered polymer created from many single units linked by lots of ester bonds. Polyester is also produced naturally in the cutin of plant cuticles. Synthetic polyester fibers make up the fabric giving great strength, shrink and crease resistance whilst remaining light weight. Dartex works with polyesters for many end uses such as a mattress cover or wheel chair seat!

Polyurethane open

The guys in the white coats say polyurethane is a class of polymers which contain urethane linking groups forming big long spaghetti like chains. The recipe includes isocyanate functional group which bond to hydroxyl group forming the urethane link, it’s just like magic!

The fun doesn’t stop there. There are two types of Polyurethanes: aromatics containing carbons in a ring structure and aliphatics with the carbons in a line.

The Dartex scientists have chosen polyurethane for its abrasion and water resistance, a high load bearing capacity, excellent stretch and breathability. This makes polyurethane great for skin contact products.

Alternative coating polymers are poly vinyl chloride (PVC), silicone, rubber, polyamide, polyester and acrylic blah! blah! blah! Our scientists don’t like these so much ; they say they give less stretch, breathability and are less environmentally friendly.

Printed Fabrics open

Fabric can be dyed, scoured or printed and Dartex works with them all. Dying adds colour to the material using special chemicals. Scouring fabrics intensively washes the textiles to remove any impurities such as oils and dirt making the fabric all nice and clean. Scouring is normally done to prepare the fabric for dying or printing but plain old scoured fabric can still be used as it is. Printing fabrics gives colour, patterns or text again using dyes or pigments. Many printing methods exist such as rotary screen printing, heat transfer printing and block printing exist. Printing or dying your fabric before coating can add vibrancy, prevent seams showing or allow complex designs, messages or images to appear on your fabric.

Proban open

Proban or cythioate and Pyrovatex are organophosphate based flame retardant treatment processes. The fabrics are chemically treated with the organophosphates, an alternative environmentally friendly flame retardant compared to halogens. These materials are mainly used for protective clothing or for equipment in high fire risk environments.

Protection Against Fungi and Bacteria open

Fungi and bacterial protection simply means their growth is inhibited. Fungi like to snack on polymers so we add antifungal ingredients to put fungi on a strict diet. Dartex fabrics last longer, preform longer and taste bad for longer! (To fungi at least). Dartex likes to help protect patients from getting any nasty bugs, pressure sores or discomfort through material failure so we give all our products protection against fungi and have invented Silver3 Technology for full microbial protection.

PU open

PU is a commonly used acronym. It can have two meanings. The first is 'Polyurethane', and the second is 'Pressure Ulcer'.

Pyrovatex open

Proban or cythioate and Pyrovatex are organophosphate based flame retardant treatment processes. The fabrics are chemically treated with the organophosphates, an alternative environmentally friendly flame retardant compared to halogens. These materials are mainly used for protective clothing or for equipment in high fire risk environments.

RF Weldable open

Radio frequency welding is the use of radio waves to weld plastics together. We can also call this process high frequency welding. What makes radio frequency possible are the properties of the polymers themselves. Some polymers have dipoles, meaning the molecule has changes. When alternating high frequency radio waves and pressure are applied to the plastic the molecules move creating heat caused by friction. Radio waves are usually at 27.12 MHz that’s 27,000,000 molecular flips per second! Caused by the dipole trying to keep up with radio waves that would defiantly make you sweat! Under the welding conditions the polymers can be pushed together creating a neat join. Radio Frequency welding is very fast connecting polymer layers forming a strong, constant and leak proof seal! This form of welding is the most common for polyurethane coated fabrics so many of Dartex fabrics are suitable.

Scoured Fabrics open

Fabric can be dyed, scoured or printed and Dartex works with them all. Dying adds colour to the material using special chemicals. Scouring fabrics intensively washes the textiles to remove any impurities such as oils and dirt making the fabric all nice and clean. Scouring is normally done to prepare the fabric for dying or printing but plain old scoured fabric can still be used as it is. Printing fabrics gives colour, patterns or text again using dyes or pigments. Many printing methods exist such as rotary screen printing, heat transfer printing and block printing exist. Printing or dying your fabric before coating can add vibrancy, prevent seams showing or allow complex designs, messages or images to appear on your fabric.

Spray Ratings open

The spray rating test measures the opposition of a fabric to surface wetting but not water penetration. Water falls through a shower head onto the fabric. The water pattern is examined and graded using standard guidelines. This test lets us know exactly how our fabrics will perform when confronted with a splash or spillage!

Stain Resistant Finish open

Some Dartex fabrics have a water and stain resistant finish meaning the fabric property resists spots and stains. The fabric is treated to prevent liquid wicking into the material allowing liquids to bead and roll off. This is not the same as waterproof, if you rub a bead into the surface it will wet in through the fabric. The Dartex quality technicians use a spray rating method to score the repellent surface on a standard scale. A stain resistant fabric does exactly what it says on the tin!

Tear Strength open

Tear strength is the force necessary to tear a material. This test tells us about our fabrics strength and behaviour. At Dartex we test tear strength using three methods the tongue tear, the single tear test, and the trapezoidal tear. The single tear test requires a sample cut into trouser shape and the ‘legs’ are placed into opposite jaws of a tensile tester. The fabric is torn apart and the tear strength/force is recorded. Ouch!

Tongue Tear Strength open

Tongue tear strength is the force required to tear fabric when using the tongue tear method. It does exactly what it says on the tin! This test tells us about our fabrics strength and behaviour. Dartex uses the tongue tear test following the British Standard procedure BS 3424 (1982). A ‘tongue’ strip is cut out from a square piece of fabric and the tongue and two remaining strips are clamped in opposite jaws of a tensile tester. The fabric is then torn apart and the tear strength is recorded. You don’t want the handles to tear of a mattress when you turn it.

Towelling Fabric open

Towelling Fabric is a material with loops on the surface that can absorb large amounts of water. We will all have used a towel when we get out of the bath, this is the same stuff. Towelled fabric can be made by weaving or knitting and is made using two beams. Terrycloth is the alternative name for this material used for towels, bathrobes and bed linen.

Transfer Coating open

Dartex makes our material by transfer coating and the end result is a one side polymer coated fabric.

The Dartex coating Line

The Formula:

Paper + Polymer + Fabric - Paper = Product

To make a Dartex fabric we begin by coating polymers onto a carrier with a release surface, normally paper.  This creates a thin film of the polymer.  We keep building up the polymer layers like a sandwich with the final layer being an adhesive. The fabric is pressed onto the polymer fixing all the layers to the textile. After a swirl of hot air in the oven it is released from the paper for its life in service.  A Dartex fabric is born! With the best survival equipment for being cleaned, stretched and used for its working life, it is a hard life!

A wide variety of fabrics can be coated at Dartex retaining their characteristics such as stretch and recovery. The coating is a uniform layer and the release surface used can change the look and feel of the material. The pattern on the release surface makes an everlasting “first impression” on the finished product. By tailoring our formula the Dartex production line gives our products the perfect performance features for your needs.

Transfer Lamination open

The formula:

Paper + Polymer + Fabric - Paper + heat = Product

Dartex can make products by transfer laminating also. It is a lot like transfer coating but instead of pushing the fabric into wet adhesive it is pressed into hot, dry adhesive. To make a laminated Dartex fabric we begin by coating several polymer layers onto a carrier with a release surface, usually paper and then we bake to perfection! The fabric meets the freshly made polymer layers over a hot roller squeezing them together creating a new Dartex laminated product! We can do this on both sides of the fabric making a double coated fabric. It’s just like having your eggs easy over! The Dartex double coated material adds an extra safety layer for that performance piece of mind. Dartex can modify our base formula to offer stretch control, water impermeability and breathability whilst still keeping the fabrics original stretch characteristics.

Usable Width open

Usable width is the width of material which can be taken from the Dartex production line and created into an end product such as a mattress cover. Our usable width range is 90-154cm.

Wales open

Wales isn't just a great country in the UK, they are also columns of loops along the length of a fabric. ‘Wales’ are the opposite of ‘course’! Easy peasy.

Warp Knit open

Warp knitting is a form of knitting where the yarn zigzags along the fabric length following the wales. There are several types of warp knitted fabrics such as tricot, raschel knits, and milanese knits. All warp-knit fabrics are resistant to laddering and unraveling and there’s a high dimensional stability more so than the weft knit. This makes a warp kitted fabric an excellent choice for a coated material!

Warranty open

All of Dartex products come with a guarantee. We like to give you a minimum 12 months guarantee for your protection usually starting from when the material has been transformed into the final product. This means that after a year the fabric remains in spec. That isn’t the case with everyone else so it is worth checking the small print. The length of the guarantee however does depend on a number of terms and conditions such as the product type and its end use.

Washability open

Our products may be in high contact or transfer areas so we know naturally things will get dirty with use. Dartex makes most/all our products whether it be printed, dyed or scoured machine washable for reuse and your ease. The working environment will be cleaner, fresher and the risk of cross contamination and infection is reduced. Our Dartex quality technicians test wash many times checking for faults and structural changes ensuring the same performance after ever wash. We wash our products between 40 and 95⁰C depending on their end use. The NHS MAC manual requires 71⁰C for decontamination and Europe at 95⁰C meaning our Dartex fabrics fit the bill for international healthcare use.

Water Penetration Resistance open

Water penetration resistance is the inability of liquid water to pass through a barrier under certain conditions such as high pressure. It means it is really, really waterproof, and so are our fabrics. Keeping water out keeps many other fluids out too, protecting whatever’s underneath from the not so nice things. For our fabrics to be water penetration resistant they need to be strong The Dartex quality technicians exert 120kpa of water pressure onto the fabric (that’s the equivalent of a 12 metre column of water stacked on top!!). This is done using Dartex’s hydrostatic head or Shirley hydrostatic head test apparatus.

Water Repellent open

Some Dartex fabrics have a water and stain resistant finish meaning the fabric property resists spots and stains. The fabric is treated to prevent liquid wicking into the material allowing liquids to bead and roll off. This is not the same as waterproof, if you rub a bead into the surface it will wet in through the fabric. The Dartex quality technicians use a spray rating method to score the repellent surface on a standard scale. A stain resistant fabric does exactly what it says on the tin!

Water Vapour Permeability open

Water vapour permeability is the movement of water vapour molecules through a material, this material however is impermeable to liquid water. Sometimes this is called breathability which can be confusing as air has nothing to do with it!

The water vapour can travel in either direction depending on the humidity each side of the material. The molecules will move from the higher humidity to the lower as a natural instinct. A healthy human body loses around 450-750g/m2/day of water vapour so interference with this loss would make things pretty uncomfortable, so we need a fabric that works alongside the body that’s breathable.

To make something ‘breathe’ we could make a micro-porous material using special polymers creating tiny holes too small to let liquid water pass through. These materials however tend to damage easily and potentially anything small enough to fit through these holes will try to sneak through like a virus.

Hydrophilic (meaning water attracting) materials such as polyurethane can attract water molecules and transmit them through the polymer coat. There’s no holes so it remains tough and completely impermeable to liquid water, along with everything else, pretty clever stuff!  This makes polyurethane a great choice for close skin contact and for places microbes maybe hanging around waiting to cause trouble.

There’s loads of ways of measuring water vapour permeability but to make it even more annoying you can’t compare products that have been tested using different methods. A moisture vapour permeability figure means nothing unless you know exactly which test method was used. Each method places the fabric under different conditions and some of these conditions favour the transfer of water vapour more than others.

Here is a list of a few tests used to measure water vapour permeability:

  • The index method BS 7209:1990 aka BS3424 (37) 
  • ASTM E96
  • The Hohenstein sweating guarded hot plate ISO 11092
  • Payne Cup ASTM D 1653

Here at Dartex we use the ‘BS 7209:1990’ aka BS3424 (37) as our main test, and sometimes use the Payne Cup ASTM D 1653 test, although this is much less common.

Waterproof open

Waterproof is the ability of a material or fabric to remain fully resistant to water penetration just like your garden pond/paddling pool. Water Resistance is when a material is designed to resist but not to wet, instead it runs off like water off a ducks back. The textiles industry has various ways of testing their claim to waterproof or water resistant fabrics. Hydrostatic Head Hydrostatic Head is the measure of water pressure that a fabric can withstand. The water pressure is increased on one side of the material to greater than 100kpa, that’s about half the pressure of your average car tyre! Spray Ratings The spray rating test measures the opposition of a fabric to surface wetting but not water penetration. Water falls through a shower head onto the fabric. The water pattern is examined and graded using standard guidelines. This test lets us know exactly how our fabrics will perform when confronted with a splash or spillage!

Weft Knit open

Weft knitting is a form of knitting where the yarn loops up and down across the width of the fabric following the course. This is the most common type of manufactured knitting. There are several types of warp knitting such as single jersey, purl, and rib. You can knit with a single or many different yarns to make patterns in the fabric! Weft knitted fabrics normally has good stretch and have excellent drape even after coating, making them suited for lots of jobs!

Wipe Cleanable open

Dartex knows washing isn’t everyone’s favourite chore and in a high demanding environment frequent industrial washing is not always possible. Dartex have created a range of fabrics which are wipe cleanable making cleaning practical and easy. This is convenient for high patient transfer in healthcare, decontaminating the fabric quickly for reuse. The Dartex quality technicians test our wipe clean fabrics for chemical resistance towards cleaning agents such as alcohol and chlorines for performance insurance. We test for long and short term chemical exposure followed by water penetration and abrasions resistance investigations. This proves a Dartex fabric can live on wipe after wipe!

Woven Fabric open

Woven fabric is a cloth created by weaving. Woven fabric has a weft with yarn running across the fabric width and a warp with yarn running down the length like criss crosses! There are several types of woven fabric plain-weave, twill-weave and satin weave. These can be used for various products such as clothing, furniture and curtains. Woven material is however prone to fraying at the edges unless treated and they only tend to stretch diagonally to the warp and weft direction limiting the stretch properties. Woven textiles are measured in Ends and Picks. Ends per inch are the number of warp threads per inch and picks per inch is the number of weft threads per inch of woven fabric.