Ingredients
- 4 large eggshell halves, rinsed and dried, about 2 inches wide each
- 1 cup alum powder, food-grade or pickling alum
- 1 cup hot tap water, about 120 to 140 degrees Fahrenheit
- 1 tablespoon white craft glue, such as Elmer's
- 1/2 teaspoon red liquid food coloring
- 1 tablespoon fine white salt, optional, for a slightly more textured crystal surface
- 1 small paintbrush, about 1/4 inch wide
- 1 small glass measuring cup, at least 2-cup capacity
- 1 wooden craft stick or teaspoon for stirring
- 1 shallow baking dish, about 8 inches by 8 inches
- 4 small paper cups, 3 ounces each, for supporting the shells
- 1 sheet wax paper, about 12 inches by 12 inches
- 1 clean dish towel, about 18 inches by 24 inches
- 1 pair nitrile or household cleaning gloves (optional for sensitive skin)
- 1 pair safety glasses (helpful while mixing and brushing)
- 1 disposable table covering, about 24 inches by 36 inches
Instructions
- Cover your table with the disposable covering to protect the surface.
- Place the clean, dry eggshell halves in the shallow baking dish, cut side up. Use paper cups around them to keep them steady.
- Brush 1 tablespoon of white craft glue over the inside of each shell half, ensuring a thin and even layer.
- Sprinkle about 1 tablespoon of alum powder across the wet glue inside each shell and tap out excess alum back into the dish.
- Leave the coated shells for 30 minutes, until the glue is no longer wet.
- Pour 1 cup of hot tap water into the glass measuring cup and add the remaining alum. Stir for about 2 minutes.
- Add 1/2 teaspoon of red liquid food coloring and, if desired, 1 tablespoon of fine white salt. Stir slowly.
- Let the solution sit for 5 minutes, then stir once more. Pour enough solution into each shell to reach about 1/4 inch below the rim.
- Set the baking dish in a dry place away from direct sunlight and leave the shells uncovered for 24 hours.
- Check the shells after 24 hours and pour off any remaining liquid without scraping the crystal surface.
- Set the shells on fresh wax paper in the paper cups and let them dry for another 12 hours.
- Brush away any loose grains with a dry paintbrush and repair any spots with a dab of glue and a sprinkle of alum if needed.
- Wipe the outside of each shell with a damp cloth and let them air-dry for 1 hour before displaying.
Notes
This project is suitable for beginners and can be made with supervision for children aged 8 and older. Safety precautions should be taken when handling alum and hot water.
