Bluing (fabric)

White fabrics acquire a slight color cast after use (usually grey or yellow).

Bluing is not permanent and rinses out over time leaving dingy or yellowed whites.

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.

In Australia it was used as a folk remedy to relieve the itching of mosquito and sand fly bites.

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(II) sulfate.