Coral Crystal Garden Using Laundry Bluing

Coral Crystal Garden (Anne Helmenstine)
Coral Crystal Garden (Anne Helmenstine)

The coral crystal garden is a colorful and interesting crystal project that resembles an undersea scene. The crystals look like delicate coral. Fortunately, you don’t need an aquarium or access to the ocean to grow these crystals. This simple project only requires ammonia, salt, and laundry bluing:

Coral Crystal Garden Materials

  • 3 tablespoons household ammonia
  • 3 tablespoons iron(III) ferrocyanide solution (Mrs. Stewarts Laundry Bluing) [buy from]
  • 1 tablespoon table salt
  • food coloring or water soluble markers
  • cardboard or construction paper
  • scissors
  • shallow dish or plate

It is unlikely you’ll find laundry bluing at your local store, but it’s readily available online. A bottle is not too expensive. You can save it for other projects or use it to make your whites whiter (its original intended purpose). If you have access to a chem lab, you can use an aqueous solution of the iron ferrocyanide.

How to Grow the Crystal Garden

  1. Cut out the paper or thin cardboard so that it resembles a coral undersea grotto. Be creative!
  2. Color your scene with water soluble markers or dot it with food coloring. You do not need to completely cover the scene because the crystal growing solution with spread the colors outward.
  3. Prop up the scene on a plate or shallow dish.
  4. Mix together the ammonia, bluing (iron ferrocyanide solution) and salt.
  5. Dribble some of the solution onto the paper scene. Pour the remainder into the bottom of the dish so that the paper can absorb it.
  6. Set the undersea scene somewhere that it won’t get bumped or disturbed. The crystals will grow over the next several hours. Expect your crystal scene to be complete overnight or within 1-2 days. The length of time depends on temperature and humidity. The solution will evaporate more quickly when it is warm and dry. If you like, you can add more crystal growing solution to the base of the scene.

Caring for the Crystals

You can keep the crystals when they are done growing, but expect them to lose some structure over time. Fragile crystals may break off or the salts may re-dissolve under high humidity.

Related Crystal Projects

Watch a Time Lapse Video of a Coral Crystal Garden Growing