It may seem like a simple piece of chalk, but it is the beginning of a million activities taking place every day on playrooms, sidewalks and playgrounds. It unleashes hopscotch. Foursquare. Tic-tac-toe. It is the brush that paints portraits, landscapes and still lifes. It is hangman and mazes and puzzles. It’s all of these things without batteries or screen. As luck would have it, making sidewalk chalk at home is surprisingly simple and makes a pretty good rainy day activity all its own (with adult supervision).
Homemade sidewalk chalk is easy to make using plaster of Paris and something to pour it into. We like the size and heft of chalk made using toilet paper rolls, but cardboard tubes of other sizes can be used or silicone molds like those used for candy or baked goods will also work.
Use duct tape to seal one end of the toilet paper rolls. This recipe is built to mix one stick of chalk at a time to make as many or as few colors as paint or inclination permits.
Cut wax paper sheets half an inch to an inch longer than the cardboard tubes and line each tube with a sheet. Make sure the edges of the wax paper overlap so that no cardboard is left exposed inside the tube.
In a sandwich-size plastic bag, combine 1 cup plaster of Paris and 1/2 cup warm water.
To color chalk, add about 2 tablespoons of tempera paint to the bag. Tempera paint is a non-toxic washable paint often used for finger painting. Use as much or as little as you’d like for creating pastels or richer colors, but more paint in the mix will result in weaker chalk.
Seal the bag and squeeze and roll by hand until a thick, evenly-colored paste forms.
Cut a hole in a corner of the bag about half an inch wide. Slide the open corner inside one of the prepared cardboard tubes and squeeze to pipe the plaster into the tube to fill. Make sure there are no gaps or large air bubbles. Mix new bags of plaster for each color.
Allow to rest for 24 hours to harden.
Peel the cardboard and wax paper off of your finished chalk.
Hit the driveway! This mighty sidewalk chalk is a handy playtime tool, easy to clean up and is almost as much fun to use as it is to make.