Silk fabrics

Infobox on Silk fabrics
Example of Silk fabrics
Facts
Origin	India China Japan Brasil Thailand
Stowage factor (in m3/t)	3,4 m3m/t (bundles)
Humidity / moisture	Relative humidity: 65-70% Water content: 9-11%
Ventilation	-
Risk factors	See text

Silk fabrics

Description / Application

Silk is a natural protein fibre, some forms of which can be woven into textiles. The protein fibre of silk is composed mainly of fibroin and produced by certain insect larvae to form cocoons. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture). The shimmering appearance of silk is due to the triangular prism-like structure of the silk fibre, which allows silk cloth to refract incoming light at different angles, thus producing different colours.

Silks are produced by several other insects, but generally only the silk of moth caterpillars has been used for textile manufacturing. There has been some research into other silks, which differ at the molecular level. Many silks are mainly produced by the larvae of insects undergoing complete metamorphosis, but some adult insects such as webspinners produce silk, and some insects such as raspy crickets produce silk throughout their lives. Silk production also occurs in Hymenoptera (bees, wasps, and ants), silverfish, mayflies, thrips, leafhoppers, beetles, lacewings, fleas, flies and midges. Other types of arthropod produce silk, most notably various arachnids such as spiders.

The entire production process of silk can be divided into several steps which are typically handled by different entities. Extracting raw silk starts by cultivating the silkworms on Mulberry leaves. Once the worms start pupating in their cocoons, these are dissolved in boiling water in order for individual long fibres to be extracted and fed into the spinning reel.

Silk has a smooth, soft texture that is not slippery, unlike many synthetic fibres.

Silk is one of the strongest natural fibres but loses up to 20% of its strength when wet. It has a good moisture regain of 11%. Its elasticity is moderate to poor: if elongated even a small amount, it remains stretched. It can be weakened if exposed to too much sunlight. It may also be attacked by insects, especially if left dirty.

Silk is used to produce raw silks for ready-made garments, fancy goods, jersey goods, ties and dress and lingerie fabrics and as sewing and embroidery yarns. It is also used in the chemical and electrical industries (insulating material, such as cable tape) and for industrial fabrics (parachutes).

Shipment / Storage

Raw silk is exported in folding cartons or reels, i.e. as silk filaments wound in skeins. The silk skeins are packed in bales and wrapped in a double layer of jute fabric and plastic film.

Silk products are packed in boxes, for example, which are lined with water-resistant paper. Silk is strongly hygroscopic and has a high swelling capacity.

It is a very delicate cargo which can also be carried under temperature control for hanging silk garments, silk yarns and silk cocoons. (Dri-Bags can also be used to control humidity).

General
Temperature setting	13°C
Temperature range	12°C-14°C
Humidity	Active on 70%
Fresh air vents	10% open
Drain holes	Closed
Cooling down period	4 days, maximum reduction of 5°C (down) per 24 hours

Risk factors

• Self-heating / spontaneous combustion
• Odour
• Contamination
• Mechanical influences
• Shrinkage / shortage
• Insect infestation / Diseases