Grow your own salt crystals

To make this miracle happen you will need the following items

Table Salt
2 glass jars or containers (clean)
1 large table spoon
Some short string
1 pencil
Sellotape

Yes, that's it!

Stir the salt into boiling hot water until no more salt will dissolve into the water.

You may see crystals at the bottom of the jar. It's important that the water is as close to boiling water as possible.

Hot tap water is not sufficient and will produce poor results.

If you want to form larger cube crystals then you need to drape some string in the saturated salt mixture and leave this undisturbed in a cool, dry location for a few days. Before you put the string into place make sure that you empty the salt mixture into another clean contained and be careful not to pour in any undisolved salts at the bottom on the container.

I have found its best to tie the string around a pencil and use this to secure the string in place. You can use sellotape of whatever you deem appropriate to secure the pencil to the container. It's vital that the base for the string and the container is solid and free from movement in the first few days of crystallization the newly formed crystals don't have a strong bond to the string and will detach easily from the base. The string should be placed into the water and the container should be covered for best results.

You will soon start seeing salt crystals forming on the string in the next few days!

Set the container in a location where it won't be disturbed. You are most likely to get a perfect crystal rather that a mass of crystals if you allow the crystals to grow slowly undisturbed in a cool shaded location which is free from vibrations.

If you want to grow crystals quickly you can soak a piece of cardboard in the saturated salt solution. Once it's soggy place it on a pan or plate and set it in a warm sunny location to dry out. Numerous salt crystals will soon start to form on the surface.

Experiment with different types of table salt. Try iodized salt, unionized salt, sea salt, or even salt substitutes. Try using different types of water, such as tap water compared with distilled water. See if there is any difference in the appearance of the crystals.
If you are trying for the 'perfect crystal' use unionized salt and distilled water. Impurities in either the salt or water can aid dislocation, where new crystals don't stack perfectly on top of previous crystals. You can even try dissolving Cooper sulphate solution and watch the sulphate form spectacular blue crystals.

If you just want to grow a mass of crystals or a crystal garden, you can pour your saturated solution over a substrate (rocks, brick, sponge), cover the setup with a paper towel or coffee filter to keep out dust, and allow the liquid to slowly evaporate.

On the other hand, if you are trying to grow a larger single crystal, you will need to obtain a seed crystal. One method of getting a seed crystal is to pour a small amount of your saturated solution onto a plate, let the drop evaporate, and scrape the crystals formed on the bottom to use as seeds. Another method is to pour saturated solution into a very smooth container (like a glass jar) and dangle a rough object (like a piece of string) into the liquid. Small crystals will start to grow on the string, which can be used as seed crystals.

Crystals that were made from a water (aqueous) solution will dissolve somewhat in humid air. Keep your crystal beautiful by storing it in a dry, closed container. You may wish to wrap it in paper to keep it dry and prevent dust from accumulating on it. Certain crystals can be protected by being sealed with an acrylic coating (like Future floor polish), although applying the acrylic will dissolve the outermost layer of the crystal.