Attractive crystals can be made from everyday ingredients, with no specialist equipment. Table salt crystals make a popular science fair project, especially when the results are compared with crystals made from other materials, such as Epsom salt or sugar. They can also be made as a stand alone project, perhaps adding food colouring to make them more spectacular.
To make table salt crystals all you need is:
– Table salt. Different varieties will produce different types of crystals.
– A jar, or other clear container.
– A pencil.
– A piece of string.
– Something to use as a seed crystal, such as a paper clip or a ready made smaller crystal. If you are using rough string it is not necessary to use a seed crystal.
– Food colouring, if you want to colour your crystals.
What to do:
1. Boil the water.
2. Pour the water into the jar.
3. Gradually add the salt and stir it in, letting it dissolve. Continue until the salt is no longer dissolving and is instead collecting at the bottom of the jar.
4. If you wish, add a few drops of food colouring to the solution at this point.
5. Cut a length of string almost as long as your jar is tall. Tie one end around the pencil and tie the paper clip or seed crystal to the other end.
6. Place the pencil over the jar so that the seed crystal hangs down into the solution. It should almost touch the bottom of the jar.
7. Leave the jar for the crystals to form.
If you leave the jar in a cooler, darker location, it will form more slowly. Crystals formed slowly are more likely to grow into one large crystal rather than a group of smaller crystals.
The crystals should be noticeable after 1-2 days, but you may wish to leave them longer so they have an opportunity to grow larger. If you decide to leave it for a long period of time, you should place your crystal in a renewed salt solution every few days.