The characteristic red color of blood is due to an oxygen-carrying protein called hemoglobin. This protein is found inside cells, called red blood cells.
Iron binds with oxygen to carry it through the body. This link changes the wavelength of light. The higher oxygen, the brighter the blood.
Film specialists have tried to simulate this coloring as closely as possible , with more or less successful results.
The first fake blood was performed at the Grand Guignol Theater in Paris. His secret recipe: a solution of equal parts carmine, secreted by the cochineal insect, and glycerin, a viscous substance.
Decades later, dyed corn syrup was used. Movie makeup master, Dick Smith,
creator of the girl from The Exorcist and designer of the Vito Corleone look in The Godfather. He developed a recipe that revolutionized horror movies: he added methyl parabens, an ingredient used in cosmetics that preserves the properties of blood for longer, and a photographic wetting agent, which made the blood flow more evenly.
The art of passing terror!