fabric

Hemp Fiber

Hemp fiber is a fiber obtained from the stem, similar to other bast fibers, but somewhat softer than fibers from other types of stems. It was first used in countries across Asia. Hemp was grown in China around 2000 BC, and the Chinese used hemp fiber to make paper. The Japanese believe hemp is their oldest fiber. It was later brought to European countries and became an important fiber for countries in that region.

The Egyptians and Phoenicians came to use hemp after already using linen extensively. Today, the countries that grow the most hemp are Russia, India, and China. Hemp is a very hardy plant that can grow at elevations up to 8,000 feet above sea level, so it thrives well in generally warm or hot climates.

Hemp is an annual plant that must be replanted every year, but it can be grown on the same land more often than flax. It must be planted densely so the stalks grow tall and slender, with leaves only near the top. The flowers are small with 5 petals, and the fruit is small with many seeds. When the leaves at the base begin to turn yellow, that is the stage when the hemp stalks can be harvested.

Extracting hemp fiber uses the same method as extracting linen fiber: the stalks are retted until soft, the bark is peeled off and crushed, then the fibers are removed and spun into yarn for weaving into fabric. The natural fiber has a dark brown color that is difficult to bleach white, so it is usually dyed in bright or dark colors instead.

Hemp fibers vary in length depending on their intended use — long fibers are typically used in industrial applications, while short fibers are used for general purposes. The specific gravity of hemp fiber is 1.48 g/cm3, with a tenacity of 5.2 g/denier. It stretches very little, about 1.6%, and has low elasticity. Its moisture regain under standard conditions is 12%, but it can retain up to 30% of its weight in moisture when the air is very humid.

Reaction to acids and alkalis: concentrated alkalis, or alkalis at high temperature, will dissolve the fiber, but it can withstand dilute alkalis whether hot or cold. Dilute acids, especially mineral acids, will reduce the fiber's strength and eventually cause it to break. Hemp can be washed with detergents and used with bleaching agents if used in the right amount and in the correct way. Hemp fabric withstands sunlight and heat similarly to cotton fabric, and resists moths and insects well, but is not resistant to mold. To test whether a fiber is hemp, soak it in an iodine compound in sulfuric acid — if it turns blue-green, it indicates genuine hemp fabric.

Uses of hemp It is commonly used to make rope, sacks, and home decorative fabrics, woven into thick fabric used for making large bags and sacks.

 

 

 

Ramie fiber is a fiber obtained from the stem (Bast Fiber). It is a plant that has been cultivated for hundreds of years in China and the island of Formosa. The Chinese call it "China grass," and there is evidence that it was also grown and used long ago in the Mediterranean region, alongside the use of linen fiber. Today it is grown extensively in China, Japan, Egypt, France, Italy, Russia, the United States, and Indonesia.

Ramie is grown from seed, forming clumps or bushes. When first planted, the stalks must be cut back several times, then allowed to regrow, until the stems can be harvested for fiber — this takes about 2-3 years. After cutting, the bark must be peeled off by hand or machine, then the fibers are separated through a fiber-extraction process. Cleaning is done by soaking the fibers in water mixed with caustic soda for several hours, which bleaches the fibers white and removes the waxy coating on them. They are then soaked in dilute acid water to neutralize them, then washed clean and dried.

Ramie fiber is a long fiber, fairly stiff, with a beautiful white sheen close to that of silk. Ramie fiber is very strong, with tenacity ranging from 5.3-7.4 g/denier. It has low elasticity and stretches the least of all fibers. Ramie is durable and reacts chemically the same way as other cellulose fibers, withstanding mineral acids at low temperatures, and resists moths and insects well.

Uses
Ramie fabric resembles linen fiber and is therefore often used for the same purposes as linen fabric, such as making clothing, tablecloths, and other household textiles. Because ramie fabric has a fairly stiff texture, it is often blended with other fibers such as cotton and rayon, which helps make it more pleasant to use, since ramie is very strong while cotton and rayon provide softness.