The earliest examples of fake blood, from red cloth to glycerol gooSome folks believe that the pre-modern cultures simply used actual blood in plays and tableaus, for maximum verisimilitude. Alfred Hitchcock opted to use chocolate syrup as the fake blood deployed his iconic Psycho shower scene. So throughout the mid-20th century, filmmakers had to use “opaque and almost garish raspberry red” fake blood mixes, Knape explains. “From that time on, most fake blood products have been variations on a limited range of ingredients,” Knape explains. So if you’re pondering your own Halloween costume and decor right now, don’t worry too much about the fake blood you’re using.