The garden is formed by the salt after the water and ammonia evaporate away. The ammonia helps to speed the evaporation of the liquid from the mixture. The laundry bluing helps to form crystal blooms instead of crystal chunks or plates. The bluing solution is actually a colloidal suspension; it has very small particle that will not dissolve, but are held up and separated by the liquid. As the water evaporates away, the salt forms crystals using the colloidal particles as a seed, or nucleus, for growth. The liquid mixture and the salt are pulled away from the bottom of the container up to the tops of the porous material by capillary action, much the same way water spreads through a sponge. This allows you to add more mixture to the bottom and have your garden bloom and grow forever. You could experiment by leaving out the ammonia or bluing, or changing the ratios in the recipe.
Allow the container to sit open to the atmosphere overnight. By the next day, crystals should have formed on the items in the dish and your crystal garden should be starting to bloom. You can keep the garden “in bloom” by adding 2 more tablespoons of salt on the second day, then half batches of the whole mixture from time to time. Make sure to pour the liquid into the base of the container and not on top of the already formed crystal blooms, as it will dissolve them and you will have to start all over…which is also a lot of fun!
This garden produces very nice, broccoli-like salt crystals from readily available ingredients. They tend to be fragile…but quite beautiful.
For this experiment, it is recommended (not necessarily required) to have a basic understanding of high-school chemistry. To perform a sugar crystallization, most experiments involve saturating water with sugar. See . For more background knowledge on sugar crystallization, click .
Begin by mixing 2 tablespoons of salt with 4 tablespoons of water, stirring to dissolve as much salt as possible. Next add 2 tablespoons each of ammonia and laundry bluing, again mixing as you go. The mixture will be a blue, watery sludge. Pour the sludge, liquid and extra salt, on top of the porous substrate in the plastic dish. Make sure to get all the salt out of the mixing cup and onto the porous items in the plastic dish (Note: If you use a sponge, wet it first abd squeeze dry for better sludge absorbtion). All the salt may not go into solution; this is okay as long as you pour the extra salt on top of the items in the dish. The porous materials in the dish will not immediately soak up all the liquid; this is okay. The crystals will naturally grow white, like the salt. If you want colored crystals, add a drop or two of food coloring on each item in the dish. The crystals will grow that color.