Halloween is right around the corner and that means that spooky scenes with fake blood are just around the corner! Fake blood is used to add that extra scary touch to costumes, Halloween decorations, haunted houses and scenes, and in the horror movies we all enjoy this time of year.
Blood is a colloid - suspension of particles, including red blood cells (erythrocytes), white blood cells (phagocytes), and platelets suspended in plasma. Blood is a non-Newtonian, shear thinning fluid, meaning that it's viscosity decreases with an increased rate of shear. The viscosity - fluid's resistance to flow - and they color of blood (real and fake) determine the look of the blood, and in the case of fake blood the "realness". Viscosity of blood determines how it flows not only through our bodies (via blood vessels), but also how it flows out of our body - or in a scary Halloween scene or costume.
At normal body temperature (37 degrees Celsius), blood is four times more viscous than water, and as a result, it flows more slowly and it is stickier. (Scientific America) While blood is more viscous than water, if is far less viscous than 'stickier' substances, such as corn syrup or honey (by the thousands fold). These substances can be diluted with water to reduce their viscosity and achieve a flow similar to that of blood.
Blood viscosity values between 3.5 and 5.5 cP are considered to be normal by most cardiovascular handbooks. (Nader et al., 2019) The viscosity of corn syrup at 37 degrees Celsius is between 2,000 and 3,000 cP, while the viscosity of water is approximately 0.69 cP. There are endless recipes online for fake blood. To achieve a look and flow for your fake blood that mimics real blood it is recommended to mix 3 parts corn syrup with 1 part water. This combination will give you the viscosity - or consistency - you want to achieve, but you will still need to experiment with color combinations to achieve the red you desire. Mixing red food coloring with drops of blue and green can achieve the dark red color of blood, as can mixing in chocolate syrup or cocoa mix.
As we have said many times before - viscosity is everywhere and this is just one fun way to incorporate it in your Halloween tricks and treats!
Written by: Eden Reid, RheoSense Senior Marketing and Sales Operations
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