The charcoal crystal garden is a classic crystal-growing project. You use charcoal briquettes, cardboard or a sponge, ammonia, salt, bluing, and food coloring to grow a crystal garden. The components of the garden are not edible, so adult supervision is recommended.
You only need a few materials for a charcoal crystal garden:
- charcoal briquettes, cardboard, or pieces of sponge or porous rock
- table salt (sodium chloride)
- laundry bluing agent
- food coloring
- glass dish or shallow bowl (non metal)
- measuring spoons
- clean glass jar
Laundry bluing isn’t common for laundry anymore, but it’s available online if you can’t find it at the store. The key ingredient in the product is Prussian blue (ferric ferrocyanide). You can use a bit of Prussian blue acrylic paint instead of laundry bluing.
- Gather your materials.
- Place chunks of your substrate (i.e., a cardboard scene, charcoal briquette, sponge, cork, brick, porous rock) in an even layer in the non-metal pan. You want small pieces, so you may need to (carefully) use a hammer to break the material up.
- Sprinkle water, preferably distilled, onto the substrate until is has been thoroughly dampened. Pour off and discard any excess water.
- In an empty jar, mix 3 tablespoons (45 ml) uniodized salt, 3 tablespoons (45 ml) ammonia, and 6 tablespoons (90 ml) bluing. Stir the mixture until the salt is dissolved.
- Pour the mixture over the substrate layer (over the scene, brick or sponge or whatever).
- Add and swirl a bit of water around in the empty jar to pick up the remaining chemicals and pour this liquid onto the substrate, too.
- Dot drops of food coloring here and there across the surface of the ‘garden’. Areas with no food coloring will be white.
- Sprinkle more salt (about 2 T or about 30 ml) across the surface of the ‘garden’.
- Allow your ‘garden’ to grow in an area where it will not be disturbed.
- On days 2 and 3, pour a mixture of ammonia, water, and bluing (2 tablespoons or 30 ml each) in the bottom of the pan. Try to avoid pouring liquid on the delicate growing crystals.
- Keep the pan in an undisturbed place, but check on it periodically. Let it grow until your are pleased with its appearance. Enjoy!
Tips for a Beautiful Charcoal Crystal Garden
- Bluing is found in the laundry aisles of some grocery stores. If you can’t find bluing at a store near you, it is available online.
- The crystals grow quickly for this project because the substrate (charcoal or whatever you chose) has a large surface area. Crystals start to form on the porous materials and then grow as capillary action draws more fluid up from the dish. Water evaporates on the surface, depositing solids/forming crystals, and pulling more solution up from the base of the dish.
View a Time Lapse of the Charcoal Crystal Garden Growing
Here’s a video I took of these crystals growing. You can expect to see growth within about half an hour, with a good change of appearance overnight.