Bluing (fabric)
From Wikipedia, the free encyclopedia
Bluing, laundry blue, or washing blue is a household product used to improve the appearance of textiles, especially white fabrics. Used during laundering, it adds a trace of blue dye (often synthetic ultramarine, sometimes Prussian blue) to the fabric.
White fabrics acquire a slight color cast after use (usually grey or yellow), because they can never be cleaned perfectly. Adding a trace of blue color to the slightly off-white color of these fabrics makes them appear whiter. Laundry detergents may also use fluorescing agents to similar effect.
On the same principle, bluing is sometimes used by white-haired people in a blue rinse.
Bluing has other miscellaneous household uses, including as an ingredient in rock crystal "gardens" (whereby a porous item is placed in a salt solution, the solution then precipitating out as crystals), and to improve the appearance of swimming-pool water.
Blue colorings have been added to rinse water for centuries, first in the form of powder blue or smalt, or using small lumps of indigo and starch, called stone blue. After the invention of synthetic ultramarine and Prussian blue it was manufactured by many companies, including Reckitt's Crown Blue [1] in Hull and Dolly Blue in Cumbria.[2] It was popular until the mid 20th century in the UK and USA, and is still widely used in India and Pakistan. In many places, it has been replaced by bleach for its primary purpose.
Bluing is usually sold in liquid form, but may also be a solid. Solid bluing is sometimes used by hoodoo doctors to provide the blue color needed for 'mojo hands' without having to use the toxic compound copper sulfate.
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