What you need
- plaster of Paris
- disposable mixing containers (try paper cups)
- disposable mixing utensils (try icy-pole sticks, plastic spoons or thick bamboo skewers)
- powdered tempera paint
- baking paper
- masking tape (not washi)
- 5–8 toilet paper rolls
- Tape off the bottom of your toilet paper rolls with masking tape, making sure there are no holes for the chalk mixture to get through.
- Line the insides of the rolls with baking paper, and then place on a baking tray or a dish lined with baking paper. Set aside.
- Add approximately 1/2 cup of plaster of Paris powder to 1/4 cup water (ratio 2:1). (IMPORTANT: Always add plaster of Paris powder to the water—not the other way around!)
- Add 1 heaped tbsp of powdered tempera paint and mix thoroughly, making sure there are no lumps. Work quickly before it gets too thick! (The consistency should be like pancake batter. Add a little more water if you think the mixture is too thick.)
- Pour mixture into the toilet paper rolls and let sit for a few hours.
- Once the plaster has hardened, peel the roll away from the chalk and continue to dry for a few days.
Tip 1. If you want to make rainbow or striped chalk, allow each layer to set slightly before pouring the next one. For swirly chalk, layer the colours and then take a bamboo skewer and run it through the liquid plaster.
Tip 2. Creating multiple colours at the same time can be challenging, as the plaster thickens very quickly. It’s best to prepare just one or two colours at a time.