Suitable fabric for a functional garment

Outerwear

The fabric we found was part of a jacket from the brand NorthBend. A search on google.com doesn’t give a lot of information about the brand. We found a site selling NorthBend outdoor shoes, which indicates the brand is specialized in outerwear. The jacket has a coated fabric called airtech, it is made of 100% polyester with a coating, which “meets the needs of the prople who demand superior protection from elements and exceptional durability.” as the brand says. 

Fabric construction and production process

The fabric is made of a plain weave of non-twisted polyester filaments with a high density. There are about 27 warps and about 11 wefts per 5 millimeter, which makes about 54 warps and 22 wefts per cm or 21 warps and 9 wefts per inch. The more warps and wefts per inch the finer the fabric is. The high density is useful to make the fabric closed, but fine fabric is not as strong. Therefore polyester is used. Polyester has the highest tensile strength besides nylon, and it doesn’t loses its strength when its wet. 

Polyester is made in a similar way as nylon. Polymer chips are melted at 280 degrees and extruded through spinnerets. After drawing, the flat filaments can be spun into yarn, textured or non-textured, directly used or cut into staple fibres. After the polyester is woven in a fabric it goes to the coating process. The clothing technology book explains: “Coating is the application of a layer of natural or synthetic polyemer to one side of the fabric, followed by fixation in a curing oven.” The coating is applied directly to the fabric. The combination of the coating and the fabric gives the fabric new properties. 

Airtech is a special coated fabric. It is protective rainwear, but still breathable. The outer shell is made of polyester, which gives the needed strength for the outdoor clothing. Inside of the jacket a membrane is applicated. We guess that the airtech coating is similar to a gore-tex coating, since they have the same properties.

On the inner shell a PTFE-membrane is applicated, outside is a lining out of polyester to make the jacket comfortable to wear. The membrane is very porous. On 1 square centimeter you will find up to 1.4 billion pores. These pores are 20.000 times smaller than a water drop, so a water drop cannot get through. But the pores are still big enough to let water vapour through. All in all the fabric is windproof and waterproof but still breathable. Breathability is not about air coming through the fabric, but about the ability to let water vapour escape. This is important for outdoor clothing, since wet clothes make you lose heat 3 times faster than dry clothes. Every seam has a risk of a possible leak in the fabric. It is very important to protect the seams by using a seam tape, which closes the small holes of the sewing machine. The coating is a synthetic polymer. This polymer is applicated to one side of the fabric. After the application the fabric has to run through a curing oven to fix the membrane.

Testing

Whereas the label implies the jacket is water and windproof and the jacket should let water vapour out of the jacket to breath, we performed several tests to proof it. We performed a water resistance test, a water vapour permeability test and a tearing test.

Water resistance test

The water resistance test uses pressure to press water to the surface of the fabric and measures at which pressure the water goes through the fabric. When the test starts the observer should press  a button when he/she sees the first water drop. After seeing the third water drop the machine stops the process and measures the pressure in mili meter water column. Mili meter water column means the pressure it gives of putting a column of water of a mili meter on top of the fabric.

 

 

We performed 3 tests. During the first test the third tinny water drop ran through the fabric at 392 mmWC. During the second test the machine stopped at 384 mmWC. Compared to other jackets with a similar coating the mmWC can go up to 10.000, so these results are not that good. Another sample has been tested a couple of weeks ago and had result of 955 mmWC. We figured that we were testing the lower back of the jacket. Since it is a secon hand jacket, this part may have lost its performance. We did a third test using the upper part of the back and we let the machine run until all the water would splash through. As you see in the movie the machine stopped the test at a 12.500 mmWC when the fabric started to tear from the pressure. It took 16 minutes and a lot of water came through the fabric. 

Water vapour permeability

It is pretty difficult to measure the breathability of a fabric, whereas it is difficult to measure vapour going through a piece of fabric. In the lab of TEKO it is possible to measure it. The test consist out of a can filled with water and on top lies the fabric which is sealed so no water can go out. The can will be placed in a machine which makes it slowly circle. Before the can is placed in the machine it will be weighted. If the fabric has circled for 24 hours, the can should be weighted again. Using a formula is it now possible to calculate the water vapour permeability. 

We started the test at 6-3-2013 at 14.22 and we ended the test at 11-3-2013 at 13.22. the test has run for 54 hours. We tested two functional textile to make comparisons. Our textile started with a weight of 135.22 grams and ended with a weight of 120.54 grams. It lost 14.68 grams of water. The other fabric was of 135.32 grams ended with a weight of 107.14 grams. It lost 28.18 grams of water. When we opened the cans we could see our fabric significantly lost less water. The table also shows that the other textile has a much better breathability than our fabric. The jacket we’ve found is probably not a nice to wear when you are sweating and it is cold outside, whereas all the sweat cannot leave through the fabric and you will get wet and cold wearing the jacket. 

The formula which is used is: (weight before – weight after)/ (factor of surface X time) X 24 hours = Water vapour permeability. The higher the outcome the better the breathability.

Tearing test

The jacket should also be strong. Therefore we did a tearing test. We performed 4 tests both in the warp and the weft direction. During the first test we used load d to tear a piece of fabric in the warp direction. The result was 10.64 Newton and the machine advised to use a lighter load. So for test 2 we used a C load in the warp direction and the result was 12.41 Newton. We also tested the fabric in the weft direction. The third test we used a B load and tested in the weft direction and the result was 16.51 Newton. The last test gave a result of 16.85 Newton. The fabric is stronger in the weft direction, whereas there are more warps. But we were surprised that the results are significantly lower than the tearing test we performed with the silk fabric. It is really easy to tear the fabric. 

Weight is 152 grams per square meters and 4.50 ounces per square yard.

Properties

We already wrote about the strength, the water resistance and the breathability and tested all of these properties. Polyester has a high abrasion resistance. As mentioned before the wet strength is the same as dry and also should be, whereas it should not lose strength when the jacket will get wet. 

The breaking extension is between 15 and 50%. Probably the coating will break easier than the polyester itself, which lower the property of the polyester. Polyester is wrinkle resistant, which is a good quality for this jacket, whereas the coating shouldn’t be ironed at a very high temperature. Polyester scarcely absorbs water, but it can transport liquid. Therefore the breathability of the coating should be good. 

It is possible to create polyesters with a lot of different properties, like high strength, flame resistance, high shrink, high crimp, antistatic or low pill. We are not sure which treatments are used to apply which properties to this fabric. 

Care instruction

The care instruction states the jacket can be washed at 40 degrees, it should not be tumble dryed, nor bleached. It can be ironed on the lowest temperature and the jacket should be washed with similar colors. Probably the jacket can withstand a higher temperature, but it is not certain what will happen with the coating. 

References

Clothing Technology from fibre to fashion fifth edition 2008

Fabric for fashion, The swatch book first edition 2010

Gore-tex.com

Suitable fabric for evening wear

We wanted to know more about silk and we found a silk tie in the second hand store. A silk tie or bow tie is essential for a classic evening dress code. 

Silk Filament

 

The silk filament consists of fibroin. Two of these fibroin fibres make one raw silk filament. The two fibroin fibres are surrounded by sericin, which is a silk gum, that holds the fibres together. It is water-soluble and can be pigmented. 

Production of silk

The silk in this tie probably is originating from the mulberry silkworm. After coming out of the egg, the caterpillar develops itself from 2 mm to a big silkworm. It feeds itself with a large quantity of mulberry leaves. After 30 days the silkworm is as large as a middle finger and begins to pupate. The silk fluid comes out of 2 glands. After 3 days the spinning is done and 3000m of silk are produced. The final cocoon has the size of a pigeon´s egg. 

14 days later the pupa transited to a moth and crawls out of the cocoon. The moth destroys the cocoon to crawl out. Therefore the pupa has to be killed to produce silk. The cocoon is placed in hot steam or hot air. After that the cocoon is put in hot water to find the end of the filaments. Then the filaments are wound up on a reel. The silk filament is really thin, therefore 7 to 10 filaments are reeled together. This silk is called net silk and is used for the finest fabrics. The net silk will be twisted together in the silk throwing machine. Spun silk is made of the longer fibres and therefore very soft and smooth. It is also called Schappe silk. The shorter fibres are spun into an irregular yarn called Bourette silk.

Materials

When we took it apart we saw that there are 4 types of fabric used in the tie. All of the fabrics in the tie have a special purpose. 

Material 1

The outside is made of 100% silk with satin weave with a pattern. The interlacings in satin weave are distributed uniform to create a very shiny fabric. There are less interlacings in a satin weave than in a plain weave. Therefore you have a predominance of warp on the surface and the fabric looks very lustrous.The fabric of the tie is usually cut on the bias.  

The fabric is yarn dyed and the yarns are twisted in a S-direction.

The fabric of the tie is usually cut on the bias. This is done, because the fabric can handle the tug. Therefore the pattern is often diagonal too. 

 















Material 2

 

The second material is a lining made of polyester. It is between the silk and the woolen lining. It is not dyed and not twisted. It is made in a loose plain weave. The lining should protect the silk from the scratchy woolen lining.

Material 3

The third material is a woolen lining which is constructed in a doubled plain weave. It is not dyed and twisted in S-direction. The lining of the tie is very important. It should be a soft and elastic fabric. Therefore in high quality ties wool is used. The lining functions as a cushion to fill up the tie and smoothen the silk fabric. With the lining it is easier to tie the tie and to keep the form.

Material 4

 
 The last material is a cotton fabric of a plain weave construction. The fabric is not dyed, but maybe bleached. The yarn is twisted in Z-direction. This layer is used to make the tie even more stable and voluminous.

Testing

Washing

The care label stated that the tie is only allowed to clean by dry cleaning. We were curious what would happen if we washed the tie. Therefore we used the A1S program, which washes on 40 degrees for 30 minutes with a detergent, but without steel balls, since silk is a very delicate fibre. There were no changes in the appearance, but the silk does not feel so soft anymore.

Tear Strength 

We also performed a tear strength test. We tested the fabric in the warp direction and in the weft direction. 

In the warp direction we put on a D load and the result was 50.49 Newton. 

In the weft direction we also put on a D load and the result was 41.26 Newton.

We also try to test the tearing strength in the diagonal direction, in which the tie is cut. But it teared in the warp direction with 46.65 Newton.

Weight

Weight is 104 gram per square meters and 3.05 ounces per square yard. 

Properties

In a tie, silk doesn’t have any functionality rather than appearance and feel. Still we will state the properties of silk as it is used in clothing to show what silk can do when it is used in garments. 

Silk can give a cooling effect when filament silk is made into fine fabrics with a small volume of enclosed air. Still, silk can be warm by creating a layer of air between the fabric and the skin, which cannot escape easily. The adsorption of water is the same for silk as it is for wool. It can absorb and hold about 1/3 of its weight of water vapour without a wet feeling. The main property of silk is the next to skin comfort. Silk is very pleasant to wear because of its fineness and softness. 

As we’ve seen, silk is very strong and has a very good tenacity. The extensibility of silk lies between 10% and 30 percent. In the tie it is not possible to stretch it, also because of the other added materials inside the tie. A very good property of silk is that the resilience is outstanding. It does almost not crease at all and wrinkles are smoothening out easily. A good property for women’s blouses is that it doesn’t built up electrostatic charge, because it always contains moisture. 

Care instruction 

The most severe laundering conditions that a fibre can tolerate are seldom those to be recommended for a given item of clothing. The care instruction says the tie can only be cleaned by dry cleaning and can be ironed on the lowest level. As we’ve seen with the washing test, the fabric loses some of its good properties when washed. Whereas a tie doesn’t need to be washed that often it is wise to follow the care instruction. 

The tie didn’t have the silk seal, which is an internationally recognized seal that stands for pure silk and good quality. The label does say it is pure silk.