Science Smarts: Fake blood

By Patty Rooks on October 18, 2025.

With the cooler weather the past few days, I am beginning to feel fall and of course, Halloween is approaching fast. I am also noticing decorations for the season popping up around town. A big shout-out to those of you who decorated your yards and driveways for the “holiday” – they look spooky!

Well, in keeping up with a Halloween theme this month, this is a fun activity that may help you with your costume and learn a little science as well. Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

– Cornstarch

– Water

– Corn syrup (golden)

– Red food colouring

– Green food colouring

– Measuring cups

– Measuring spoons

– Bowl

– Mixing spoon

Procedure

1. Measure 175 mL (3/4) cup of cornstarch AND corn syrup. Pour into the bowl.

2. Add 75 mL (1/3 cup) of water.

3. Stir well.

4. Add 15 mL (three teaspoons) of red food colouring AND 5 mL (one teaspoon of green food colouring.

5. Mix well.

6. Mold into shapes or splatter (and allow to dry) on whatever you need fake blood on for your costume!

7. NTE: you may have to adjust the quantities of food colouring depending on what shade of red you want your “blood” to look like.

What is going on?

In this experiment you made fake blood. Did you know that blood gets it colour from HEMOGLOBIN? Hemoglobin is a protein that contains iron and is found in red blood cells. When you breathe in, oxygen diffuses in your lungs and then into the blood where it binds to the hemoglobin and is carried by the blood cells to the rest of your body.

Why does blood look red? Blood appears red because of the light. It actually reflects the colour red while absorbing the other colours in the light spectrum.

Our annual FAMILY SCIENCE OLYMPICS has arrived! Join us Saturday at Medicine Hat College from 10 a.m. to 3 p.m. This is a FREE event BUT one adult must accompany all participants. I am looking forward to seeing you there!

Patty Rooks, senior scientific consultant Praxis Science Outreach Society. Praxis has moved! We are very fortunate to be located in the Community Futures Entre Corp Building at #202 556 Fourth St. SE, Medicine Hat, Alberta, T1A 0K8. For all your science needs, please email praxis@praxismh.ca.

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