Blood FX Powder by Ben Nye
Ben Nye's Mass Casualty Blood Powder gives you heaps of hemoglobin in a hurry. Trusted by artists in film and television as well as professionals in training simulations, one jar of Mass Casualty Blood Powder converts into a gallon of regular consistency, freshly exposed blood. Simply mix with water.
The versatile formula can be thinned or thickened by using more or less water, or by substituting water with corn syrup. Washes from most fabrics and surfaces, though spot testing is suggested before use.