sciences

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Looking at the history of Bleaching

Since 5000 B.C., people have had knowledge of bleaching fabrics. Bleaching has the definition of "whitening by exposure to sunlight or by a chemical process." People have had knowledge that they may whiten [bleach] their materials by a process of moisture and extreme periods of time to sun exposure. The bleaching method, in itself, has been a rather old and well-known process to man. People in Asia, Egypt, and Europe all bleached. Egyptians were said to be experts on whitening their materials. They would use the sun to whiten all of their cloths. People have even discovered bleach before the third millennium; they had knowledge about a solution that would be mixed with wood ash, which would turn into lye [Alkaline: acid: pH scale higher than seven], they knew that this would remove color. Many years later, the Dutch established a newer and better way of bleaching in the Eleventh and Twelfth century AD. During that time, the Dutch specialized in the science of whitening laundry, and became well known for their great bleaching skills throughout the European community. They mixed the lye with sour milk to be able to soften the dangerous effects of just the plain lye. Because they monopolized the bleaching business, they didn't let anyone find out their secrets about what there methods were. Because they kept their secrets safe, their methods remained a secret for many years. The Dutch dominated and maintained their business in the bleaching trade. All manufactured linens in Scotland, which were brown, were shipped to Holland [Where the Dutch bleached] to be bleached into white linen. Their whole method was so lengthy that it could take up to eight months. To accomplish the wanted whiteness with using lye, the Dutch would have to drench and then sundry the linens, that they were bleaching, many times. This was very burdensome because it would consume up to eight weeks of time, and not to mention the land space needed for the linens to lie out in the sun. A city in the Netherlands, which there were great huge fields where they could lay the linens down in the sun, was where the bleaching process would take place at the time. The linens were soaked in lye for almost about a week as the first stage. Usually, hoe boiling potassium lye would be poured over the already soaked linens for the second stage. After that, the linens were squeezed out from the liquid and washed and then later placed on wooden containers, which were filled with buttermilk. The linens would remain in the wooden containers and dip for a little less than a week. Finally, the linens were laid over grass. The linens would lay out in the field all summer long, in the sunlight but being moist. This entire process soaking the linens in the alkaline lye and bleaching them on the grass to lay in major sun exposure, which needed to repeated five to six times to accomplish the level whiteness desired.

In 1746, John Roebuck began using watered down acid instead, which scientist fancied years before, of the buttermilk. The watered down acid was an extraordinary improvement, which resulted in the application of sulfuric acid in the bleaching process, that cut the time of bleaching down to only twenty-four hours, sometimes even less than 12 hours. This was way less than the buttermilk method. The buttermilk usually required seven weeks or even months, depending on the sunlight. The practice of bleaching was reduced from eight months to four, which made the trading of linen a moneymaker. 28 long years of using the new watered down acid, in 1774, Swedish Chemist Scheele discovered the element Chlorine, which is a highly skin irritating, green yellowish gas that belongs in the halogen section of elements. Scheele also discovered that chlorine, in itself, was able to demolish color from vegetables. This discovery inspired [1785] scientist Claude Berthollet to modify its utility in the bleaching method, which failed in the beginning. Some years later, in 1794, in a town called Gavel, which is in Paris, chlorine was tried again to bleach. The people produced a chemical by combining a potassium solution with water, and called is "eau de Gavel [water of Gavel]" However, in 1799, a greater discovery to the bleaching industry was provided when a chloride of lime was introduced by Charles Tennant, which is know what you know as bleaching powder.

[hubpages.com/hub/History-Of-Bleach]

Today, nearly household you can find bleach. It is way easier and takes less time than the other methods. It removes stains and whitens all sorts of materials by a chemical reaction that breaks down the unneeded color into smaller particles, which could be easily washed out. There are two types of household bleaches. The two main types are peroxide bleach and chlorine bleach. Peroxide bleach, which was first introduced in the 1950's, helps to remove stains, especially in high water temperatures, but will not bleach most colored materials and doesn't weaken materials, as chlorine bleach does. Also, peroxide bleach doesn't kill germs therefore added to laundry detergents, which can do so and are color-safe. Peroxide also has a longer life shelf than chlorine bleach does and therefore commonly used in Europe where the washing machines could reach up to boiling point, but chlorine bleach is the most common household. Chlorine bleach is more effective at removing stains and killing germs fabrics. Chlorine bleach is very inexpensive to manufacture and can be used in either low or high water temperatures. However, it has very strong chemical properties, which can destroy certain fabrics.

[madehow.com/Volume-2/Bleach.html]

The raw materials for the making of household bleach are chlorine, sodium hydroxide and water. Putting direct current electricity through a sodium chloride salt solution in a process called electrolysis produces the chlorine and sodium hydroxide. By mixing chlorine and sodium hydroxide you can create sodium hypochlorite, which is just common chlorine bleach. So really, bleach is just salt mixed with water that has been changed a little by electrolysis. Bleach is the found in nearly every household. It has stayed through time for whitening fabrics and is still used to whiten fabrics to this day.

[howstuffworks.com/question189.htm]


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