Silk vs. Organic Silk

Source: DKNY

Silk

About
Silk is a natural fabric and consists of animal protein fibers. These fibers are produced by various insects when building their cocoons or webs. In the commercial silk industry, silk is usually produced by the Bombyx mori and the mulberry silk moth. The mulberry silk moth is the most well-known insect for producing silk and produces the finest silk of all. Silk is one of the oldest fibers we know of and found its origin in China, around 2600 BC.

Characteristics
Highly absorbing (silk can absorb around a third of its own weight), easy wrinkling, quickly drying, robust, shiny, easy to dye and hypoallergenic. Silk is the strongest natural fiber of all and is even comparable to steel yarns in elastic strength. Silk has natural temperature-regulating characteristics which means that the fabric feels warm in the winter and cool in the summer.

Production Countries
The total world production of silk is around 130.000 tons. China is the biggest silk producing country in the world, producing around 80% of the total world production. The second major producing country is India, making 10% of the silk world production. Other important countries are Japan, Korea, Thailand, Vietnam and Uzbekistan. Brazil is also major producing country of silk and is the only non-Asian country worth mentioning. The United States is nowadays the biggest importer of silk.


Soil
Silk is usually produced by mulberry silk moths, finding themselves in mulberry trees. Chemical fertilizers and (agricultural) pesticides are needed for the cultivation of mulberry trees. Besides, this cultivation needs much land, although this is less in comparison to the cultivation of cotton. However, the plantation of mulberry trees has some positive effects such as the reduction in salinity and the discouragement of erosion through wind and water.


Labor
Silk production is highly labor intensive, especially the process of “reeling the filament” (see Processing).


Processing
The cultivation of silkworms in order to produce silk is called sericulture. The first step in the production of silk is called “hatching the eggs”. During this stage, silkworms lay eggs in an artificial environment with the right circumstances to let them lay as many eggs as possible. The female produces around 300 tot 400 eggs at the time. The silkworm dies right after laying these eggs. After 10 days, the eggs hatch into larvae (caterpillars), then comes the feeding period.

During the feeding period, the larvae get feed mulberry leaves (results in the finest silk) and grow very fast. They eat around 50.000 times of their initial weight. In approximately 6 weeks, the larvae are 10.000 times heavier than at the time of hatching and ready to spin a silk cocoon. The silkworm needs around 3 till 8 days to spin a cocoon, thereby producing one kilometer of silk filament.

When the cocoon is ready, it is treated with boiling water or hot air and the silk filaments are unwounded again, getting soft by the heat, which is called “reeling the filament”. One cocoon contains only a small amount of silk and around 2500 silkworms are needed in order to produce one pound of raw silk. Usually at this point, the silkworm (e.g. chrysalis) breaks out of the cocoon and becomes a moth. However, this would damage the silk fibers and therefore the chrysalis is killed during this process. After that, degumming starts in which the “silk gum” is removed from the silk fibers in warm water, improving the color and texture of the silk. However, the gum also protects the silk and is often left on until the dyeing process. In this case, it is called “raw silk”, because there is still gum. After degumming, the silk is ready to be woven or knitted.


Dyestuffs
Silk is easy to dye since silk fibers are highly absorbent. The impact on the environment of dyeing silk depends upon the type of dyestuff. However, it is easy to work with natural dyestuffs when dyeing silk. After the dyeing process, other processes might be used to finish the fabric such as steaming or bleaching.


Costs
Silk is known as a luxurious fabric and is quite expensive. Silk is rather scarce and takes only a very small percentage of the total textile fiber market, even less than 0.2%. However, the trading value in silk products is still very high because silk is very expensive. Raw silk is around twenty times more expensive than raw cotton.

 

Organic Silk

About
Organic silk is a natural fabric and consists of animal protein fibers. These fibers are produced by various insects when building their cocoons or webs. It is difficult to define whether silk is organic, because there are no formal standards for organic silk, although attempts have been made towards a general standard. The term “organic silk” has therefore no single meaning. In the commercial silk industry, silk is usually produced by the Bombyx mori and the mulberry silk moth. The mulberry silk moth is the most well-known insect for producing silk and produces the finest silk of all. Silk is one of the oldest fibers we know of and found its origin in China, around 2600 BC.

Characteristics
Highly absorbing (silk can absorb around a third of its own weight), easy wrinkling, quickly drying, robust, shiny, easy to dye and hypoallergenic. Silk is the strongest natural fiber of all and is even comparable to steel yarns in elastic strength. Silk has natural temperature-regulating characteristics which means that the fabric feels warm in the winter and cool in the summer.

Production Countries
The total world production of silk is around 130.000 tons. China is the biggest silk producing country in the world, producing around 80% of the total world production. The second major producing country is India, making 10% of the silk world production. Other important countries are Japan, Korea, Thailand, Vietnam and Uzbekistan. Brazil is also major producing country of silk and is the only non-Asian country worth mentioning. The United States is nowadays the biggest importer of silk.


Soil
During the cultivation of organic silk, either none or purely natural chemical fertilizers and (agricultural) pesticides should be used. However, the cultivation of mulberry trees still needs much land. On the other hand, the plantation of mulberry trees has some positive effects such as the reduction in salinity and the discouragement of erosion through wind and water.


Labor
Organic silk production is highly labor intensive, especially the process of “reeling the filament” (see Processing).


Processing
The cultivation of silkworms in order to produce silk is called sericulture. The first step in the production of silk is called “hatching the eggs”. During this stage, silkworms lay eggs in an artificial environment with the right circumstances to let them lay as many eggs as possible. The female produces around 300 tot 400 eggs at the time. The silkworm dies right after laying these eggs. After 10 days, the eggs hatch into larvae (caterpillars), then comes the feeding period.

During the feeding period, the larvae get feed mulberry leaves (results in the finest silk) and grow very fast. They eat around 50.000 times of their initial weight. In approximately 6 weeks, the larvae are 10.000 times heavier than at the time of hatching and ready to spin a silk cocoon. The silkworm needs around 3 till 8 days to spin a cocoon, thereby producing one kilometer of silk filament.

When the cocoon is ready, it is treated with boiling water or hot air and the silk filaments are unwounded again, getting soft by the heat, which is called “reeling the filament”. One cocoon contains only a small amount of silk and around 2500 silkworms are needed in order to produce one pound of raw silk. Usually at this point, the silkworm (e.g. chrysalis) breaks out of the cocoon and becomes a moth. However, this would damage the silk fibers and therefore the chrysalis is killed during this process. After that, degumming starts in which the “silk gum” is removed from the silk fibers in warm water, improving the color and texture of the silk. However, the gum also protects the silk and is often left on until the dyeing process. In this case, it is called “raw silk”, because there is still gum. After degumming, the silk is ready to be woven or knitted.

Organic silk has more or less the same processing as conventional silk. However, in the production of organic silk, less chemicals should be used. Usually chemicals (methoprene) and hormone disrupters are applied on silkworms in order to lengthen the time they spin silk.  Another difference might be that during the production of organic silk, silkworms continue their natural lifecycle; they produce cocoons when the silkworms are 35 days old and die naturally. Silk is called “peace silk” when the moth is being kept alive and can break out of its cocoon like it would normally do. This damages the cocoon fibers and the silk fibers then have to spun rather than reeled. This results in softer silk fabric. Moreover, during the production of organic silk, silkworms get a more varied diet instead of mulberry leafs only. Also in the degumming process, less chemicals are used during the production of organic silk. It is important to keep in mind that there is no general standard for organic silk, so always be critical on why silk is labelled as organic.  


Dyestuffs
Organic silk is easy to dye since silk fibers are highly absorbent. The impact on the environment of dyeing silk depends upon the type of dyestuff. With organic silk, natural dyestuffs should be used. After the dyeing process, other processes might be used to finish the fabric such as steaming or bleaching.


Costs
Organic silk is known as a luxurious fabric and is quite expensive. Silk is rather scarce and takes only a very small percentage of the total textile fiber market, even less than 0.2%. However, the trading value in silk products is still very high because silk is very expensive. Organic silk is even more expensive than normal silk.