A leuco dye is a dye whose molecules can acquire two forms, one of which is colorless.{Clarify|Here, it`s `the thing with two forms` that`s a leuco dye. Later sounds more like the `leuco dye` is the colorless form that can be made colored by some reaction|date=May 2010} For example, the spiro form of an oxazine is a colorless leuco dye; the ...