Iron oxides are most commonly found in cosmetics but can also be used as food colouring. You’ll very likely find iron oxides in your favourite red lipstick, foundation, concealer, eyeshadow, eyeliner and more. It’s also commonly used in foods like cakes, sweets and more.

Iron oxides are made with an extremely simple process. By treating a solution of ferrous sulphate with an alkali and oxidising the precipitate in hot air. Since the iron present in these oxide precipitates is in the ferric form it’s not actively available to body tissues and safe for food and cosmetic applications. This process also eliminates contamination from other heavy metals like mercury and lead.

Iron oxides are some of the oldest natural pigments known to humanity. Some of the oldest cave paintings in South Africa (up to 77 000 years old!) are made using ochre, which gets its warm colours for a high iron oxide content.

Certain shades of tattoo ink use iron oxides as a body-safe pigment.

Some less than reputable food producers have been found to treat their salmon meat with iron oxide pigments (E172) to make them appear more pink.