Also known as a salt crystal garden, the salt garden is a simple a formation composed of salt that crystallizes around some type of medium, such as sponge, coal, or a piece of brick. The crystals develop in interesting shapes, providing an attractive appearance. Creating a salt garden is a relatively common project in many grade schools, since the process helps teach children a few basic scientific principles.
A basic salt garden recipe involves common table salt, and some type of base material. Coal, a charcoal briquette, or an old brick are ideal bases for the garden. Along with the salt and the base, a small amount of ferric hexacynaoferrate, known as fabric bluing, is also introduced into the mixture. Finally a very small amount of water is required.
To begin the process of salt gardening, mix equal parts of table salt, bluing, and water. Place the base material in a glass bowl. Pour the prepared solution on top of the base material, taking care to make sure the material is coated. Mix another batch of the water, salt, and bluing. For some added color, you can also add a drop or two of mercurochrome or vegetable coloring into this second batch. Pour the batch into the bowl, allowing it to settle around the bottom and a portion of the sides of the base material.
As the water content of the salt garden evaporates, the salt will begin to crystallize, creating graceful formations on the base material. Depending on the level of humidity in your area, it may be necessary to add a drop or two of ammonia in order to expedite the evaporation process. Within a few days, the crystal formations will begin to appear, and will continue to form for some time.
Once the salt garden is actively forming, it is possible to add to the garden from time to time. This is accomplished by adding a small amount of salt, water, and bluing in equal parts around the bottom area of the base material.
Teachers sometimes use a salt garden to help young children learn about evaporation, as well as help them understand how salt can be harvested from the ocean and turned into a useful product. Because no two salt gardens ever have the same exact formation, it is possible to have each child create a garden, and enjoy how some gardens produce what looks somewhat like flowers, while others create other interesting shapes.
By continuing to feed a salt garden, it can grow indefinitely. As long as the garden is maintained at a stable temperature, has exposure to sunlight to aid in the evaporation process, and is kept in an environment with relatively low humidity, new formations will appear regularly. This means that children can create gardens near the beginning of the school term, and watch them progress for the remainder of the school year.