Advert for Reckitt's Blue

Reckitt's Blue was a laundry whitener, first marketed in Hull in the 1840s by a Quaker businessman named Isaac Reckitt. His product used a combination of synthetic ultramarine and sodium bicarbonate to produce a mild bleaching effect. Sodium bicarbonate was much cheaper than lapis lazuli, the most common whitening agent prior to the 1840s, and this made Reckitt's Blue both cheap and extremely popular.