Prussian blue, a pigment used in paints, was added to tea to enhance its color and make it appear fresher. This practice was part of the widespread adulteration of tea, which often involved drying and re-coloring used leaves. The use of such chemicals in food was eventually regulated, but it took many years to effectively control the practice.

The use of Prussian blue in tea was a subject of satire and social commentary, with poets and cartoonists mocking the practice of 'painting' food. The theme of artificial colors hiding decay was a powerful metaphor for Victorian society's obsession with appearances. This theme appears in the works of writers like Oscar Wilde and the Aesthetic movement, who explored the relationship between art, commerce, and morality.