Colored toilet paper was first manufactured in 1950s, became popular in the 1970s, when the design was formulaic and people color- coördinated everything. Then, in 1980s with the decline in sales and the expense involved, manufacturers gradually reduced quantities of colored toilet paper and almost completely disappeared. But what caused it?
There are several reasons. Firstly, the problem of dyes. Environmentalists expressed concern that the dyes aren't biodegradable; doctors began warning that dye could cause skin irritation.
One of the reasons is related to the way the human mind perceives white. It automatically decides that "white" is equivalent to "clean." White toilet paper looks cleaner than the natural color (brownish before it is bleached). Bleaching is not only for aesthetic purposes but also removes the lignin or glue from the wood. The removal of lignin can make the paper much softer. You've probably seen the old newspaper, yellowed by time. In fact, the yellow color is due to the presence of lignin in the paper. Therefore, bleaching also acquires longer shelf life.