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From a University Paper on the history of "Flax and it's impact on Early Civilizations and the development of sail material"

Quote:

Flax plant Linum usitatissimum in the process of making linen fibers.
Flax plant, Linum usitatissimum, (usitatissimum means 'most useful'). The flax plant, used as a source of fiber for the making of blankets, handkerchiefs, paper, clothing and sails, became a valuable commodity, indeed a staple of life during the 17th and 18th centuries. Its importance to world societies can be traced all the way back to ancient Egypt, Phoenicia, Mesopotamia, Greece, and Rome and through its use as a sail cloth, is also perhaps the main contributor to the spread of human culture throughout the world.
The use of flax/linen as an acceptable sail material was especially important to the world's greatest explorers. The renowned Mayflower, along with many other ships associated with our early history, had sails made from the plant's fibers. Flax was of such commercial importance in colonial America that a school for its making was established in Boston. Later, during the Revolution when England's General Howe reported that "linen goods were much wanted by the rebels" he gave the order to carry away all of Boston's linen when British forces evacuated the city. In many respects pre industrial societies did indeed center on the use of flax. This valuable commodity was and still is dependent upon two soil microbes, Clostridium felsineum and Clostridium pectinovorum.
Flax is an annual plant and, under favorable conditions grows to a height from two to three feet. The plant is characterized by bright blue flowers and a field of flax in full bloom is said to have the appearance of an inland sea. Ripened, the plants are carefully uprooted in order to preserve their fiber length and laid out to dry. Once dried, they are sorted according to size, loosely bundled and placed onto moist fields or submerged into slowly flowing streams or stagnant pools. The Clostridium bacteria, ubiquitous in soil, then begins to grow on the flax and digest pectin, a major substance of the plant. This process of "retting" the flax loosens the flax fibers preparatory to spinning.

Sail cloth in modern times:

In the beginning of the 20th century the most common sailcloth's were made with cotton or flax. Cotton, being a natural fibre, has poor resistance to rot, UV light and water absorption. Hence the coating of sailcloth with varnish, making the sails quite heavy and 'stiff'. These qualities made it unsuitable cloth sailcloth.

Nylon was one of the 1st man-made fibres to be used for sailcloth. The chemical formulation and general properties of nylon have changed little over the intervening years. It is a cheap, durable and relatively resistant to UV light, good flex-fatigue resistance and shows middle of the road strength properties. However Nylon is mostly restricted to use in spinnakers due to its poor stretch resistance. Even for spinnakers it is not the ideal material as it can absorb as much as 3% its own weight in water.

The most important development occurred in the mid 1950's when polyester sailcloth’s were developed. Until the 1980's the only widely used sailcloth was woven polyester (or Dacron, DuPont’s trade name for their polyester yarn). Dacron is a very durable sailcloth and is resistant to mould and water absorption. Dacron is also very durable making it an excellent sailcloth.

Woven sail clots have an inherent problem with its stretch resistance. Some yarns pass over and under one another. Over time as load is applied these yarns attempt to straighten out, this results in the fabric stretching. This is commonly referred to as crimp. This lead to the development of laminated cloths where the fibres are laid is straight as possible.

A further development of polyester occurred in the 90's with the development of PentexTM. A derivative of polyester which 2 and a half times the elastic modulus of traditional polyester. Which makes for sailcloth which is more resistant to stretch and holds its shape longer.

In the mid eighty's sail makers began the development of laminated sails. These were to be developed for America's cup yachts and over top end racers. The reason these were developed was that the resulting laminate is lighter, stronger and more stretch resistant.

New manufacturing methods:

In the end of the 80's and the beginning of the 90's there were developments in the sail making industry to make sails which would hold their shape better and be lighter and more durable. The results of this work were 3 different solutions, namely:
North sails 3DL system
Sobstad Genesis system
And UK sail makers Tape-Drive® system

North sails use large moulds mounted on hydraulics, these moulds can change shape to the desired shape of the sail. Then with a combination of robots and people suspended over the mould laminate films and fibres are laid down, consolidated and heated with an infrared lamp. The fibres are laid in a precise manner by a robotic arm, which lays them along the lines of principle loads. The resulting sail is extremely light and holds its shape much better than a sail made by stitching fabric together. The drawback of this method is that the capitol investment in the machinery and technology needed is huge. There is currently only one manufacturing centre for 3DL in the world, located in the US. There is doubt on whether north sails can keep manufacturing these sails, as there is a bitter dispute with Genesis about Patent issues. North sails were accused of breaching Patent and copyright law with the use of 3DL and if Genesis gets its way then North Sails will be forced to discontinue production.

The Genesis system is similar to the North sails system, the difference being that they don't use a large moveable mould like the 3DL system.

The latest development in sail technology was the Introduction of Cuben fibre. This was given its first major test aboard "team adventure" which was the Giles-Olier super cat, which took part in "The Race" in 2000. There were no major problems with the sails as the Cat powered its way round the world. At the start of the race there were light winds it could be sent then that the Cuben Fibre sails were performing very well. Team adventures speed was higher that that of her sister ships which were using older tried and tested sailcloth's. In the same race the super cat "Playstation" used a new suit of Cuben fibre. These were not as successful as aboard "Team adventure" this was put down to the factors of safety, which the "Playstation" designers used, was not nearly as much as "Team adventures". There is no doubt that Cuben Fibre will become widely used for sails in the future, its only drawback at present is its prohibitively high cost.

Cuben fibre is a combination of different fibres the precise fibres that they use has not been disclosed. At the time it came out people assumed it was some new exotic type of fibre similar to carbon fibre, this is not the case. It is manufactured in a unique process whereby large panels are laid up with as many as 7 different layers of yarn. This is lightly bonded to a Mylar substrate, which is in turn heated and pressurized in an autoclave until the layers become one. The resulting sail produced is extremely light, waterproof and has unequalled strength and stretch resistance. The laminate has the feel of heavy plastic, this means that sail repairs are easy to carry out; patches can be made up and glued on with a hot glue gun.

There has been an increase in the last decade of the use of full batten systems. These systems enable the sail designer to make the final sail conform to a better aerodynamic shape. The recent development in composite technology has enabled battens to be manufactured, which were both light strong and flex correctly. Noticeable increases in speed can be seen with the use of full batten systems compared to normally battened sails.

Vectran is a fibre the US navy developed. The US navy wanted a fibre to listening devices behind submarines. The requirements for the fibre were for the length of the tow to be constant and one, which could withstand adverse conditions. The result of the research was Vectran. It is a liquid crystal polymer, which shows similar initial properties to the commonly used grades of Aramid. Flex fatigue resistance is much higher than Aramid fibres; its UV resistance is slightly lower. However it is considerably more expensive than Kevlar. Current applications for this cloth are in endurance events such as the Volvo ocean race.

PBO was developed in the late 90's and was heralded as the new wonder material. It has higher stretch resistance than any other material, except carbon, and very high initial strength. It has one major drawback, poor light resistance. Research showed that the fibres were damaged by visible light and therefore that led to further developments in film technology to combat this problem. At present this cloth is reserved for use in high-end racing such as the America's cup and grand prix racing.

Maybe more than you wanted to know.

Trying to find sailcloth for models is not easy. It has to do with scale. Using regular materials for model sailcloth doesn't fit the scale of most models. Believe it not, I found the best material to be from fine (weave) all cotton shirts. Wash it about two times with no additives except bleach. Rinse about two times in clean fresh water (to get any remaining bleach out). Cut out the sails you need, sew seams etc, coat with a fine artists' varnish (Damar is a good one) (try one coat and see how it looks. Then maybe apply a second coat), iron with medium hot iron, and install.
Of course the wife

, may not be too thrilled that your cutting up your $50 dollar dress shirts.