The salt printing process, invented by William Henry Fox Talbot in the 1830s, was one of the earliest photographic methods. It involves coating paper with a salt solution, typically sodium chloride, and then sensitizing it with silver nitrate to create light-sensitive silver chloride in the paper fibers. When exposed to sunlight under a negative, the areas exposed to light darken, producing a visible image.

To enhance the aesthetic and archival qualities, prints were often toned with noble metals like gold or platinum. Gold toning, popularized in the mid-19th century with albumen prints, helped to increase image contrast, impart a cooler tone, and improve print stability by replacing much of the silver with more stable gold particles. This process not only added visual richness but also contributed to the longevity of salt prints.