Table salt or sodium chloride crystals are among the easiest crystals to grow. The materials are easy to find and inexpensive, plus the crystals are non-toxic.
Salt Crystal Growing Materials
You probably have all the materials you need for this project:
- table salt – sodium chloride – NaCl
- clean clear container
- piece of cardboard (optional)
- pencil or butter knife (optional)
Salt Crystal Step-By-Step
- First you need to prepare a saturated salt solution. Stir salt into boiling hot water until no more salt will dissolve. Salt may settle out at the bottom of the liquid. This is fine – just make sure none of the undissolved salt gets into your crystal-growing container. Be sure the water is as close to boiling as possible. Hot tap water is not sufficient for making the solution. As the solution cools, the saturated solution becomes supersaturated. If you want colored crystals, you can add some food coloring to this solution.
- If you want crystals quickly, you can soak a piece of cardboard in this supersaturated salt solution. Once it is soggy, place it on a plate or pan and set it in a warm and sunny location to dry out. Numerous small salt crystals will form over the span of a couple of hours.
- If you want a mass of crystals, you can simply pour the saturated salt solution into a clear container and let it slowly evaporate. Crystals will grow on the sides of the container.
- If you are trying to form a larger, perfect cubic crystal, you will want to make a seed crystal. One way to get a seed crystal is to pour a small amount of saturated salt solution onto a saucer or watch glass. As the liquid evaporates, crystals will start to form. Select a single square crystal and remove it from the dish.
- To grow a big crystal from a seed crystal, carefully pour the supersaturated salt solution into a clean container (so no undissolved salt gets in), allow the solution to cool, then hang the seed crystal in the solution from a pencil or knife placed across the top of the container. The solution needs to be saturated and cooled so that it won’t dissolve your seed crystal. You could cover the container with a coffee filter or paper towel to keep out dust, yet permit evaporation.
- Set the container in a location where it can remain undisturbed. You are more likely to get a perfect crystal instead of a mass of crystals if you allow the crystal to grow slowly (cooler temperature, shaded location) in a place free of vibrations.
Crystal Growing Tips
- Avoid using salt containing anti-caking agents. Usually, these don’t dissolve so you can filter them out. But, the particles lead to small crystal formation rather than large crystals.
- Experiment with different types of table salt. Try iodized salt, uniodized 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 uniodized 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.