Chemistry
rock crystal candy

How to grow crystals for a science fair



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Growing crystals for a science fair project is much easier than it may sound. It can also be a fun project for beginners to experts. There are many types of crystal recipes available and the ingredients for most of the recipes are items that you may already have on hand. Some ingredients can be more difficult to work with than others and parental supervision should be given to the novice or younger crystal grower.

When working on a science fair project, you need to document the steps you take in the project. Keep track of all ingredients, temperatures of your solutions and time to crystal formation. Understand crystals themselves, crystals are a structure, formed from repeated patterns of connected molecules or atoms. Nucleation is the term used for the crystal growth process. You should have a good understanding of this process so you can include the information in your project summary.

Seed crystal

If you wish to grow a large single crystal structure you will start with a seed crystal. There are several methods available to make a seed crystal. Pour your solution (see recipes below), onto a plate and allow the solution to evaporate. Scrape of the crystals formed when dry. You may also use a glass jar and hang a string inside of it, in contact with your solution. Crystals will form and grow on the string.

Crystal gardens

You may also wish to grow a crystal garden or mass of crystals. You can grow the crystals into a tree formation or geode formation. To make a geode formation, pour your solution (recipe) over a substrate. You can use a sponge, rock or piece of brick as the substrate. Cover your creation with a coffee filter or paper towel and allow time for your solution to evaporate. There are many sources available for detailed instructions on this process.

Recipe: Epsom salt crystals

Epsom salts are readily available and safe to handle. The crystals formed from Epsom salts grow quickly and easily. You will need:

  • one half cup of water
  • one quarter cup of Epsom salts
  • a shallow non-metallic dish or bowl
  • You may also use a sponge as a substrate and add food coloring if desired for effect.

Boil the water and add the Epsom salts. Stir your mixture until the salts are completely dissolved. If you wish to add color, add it while stirring. Pour your mixture into your container and allow the liquid to evaporate. You now have Epsom salt crystals

Recipe: Alum crystals

Alum is a pickling spice and available in most grocery stores. Alum crystals are easy to grow and produce large crystal formations. To make alum crystals you will need:

  • a jar with one half cup of hot water
  • a second clean jar
  • alum
  • nylon string

Add the alum slowly while stirring until no more alum will dissolve. Cover your jar with a paper towel or coffee filter and allow it to sit undisturbed for 24 hours. After 24 hours, pour your solution into a clean jar. You now should see beginning crystal formation. Tie a piece of nylon string around the best of your crystals. Hang your string into another clean jar with the rest of your solution. You will want to check on your experiment daily and if crystals begin to form on other areas of your jar just transfer your string and crystal free solution into a new clean jar.

Recipe: Borax crystals

Borax is a laundry booster, also available in grocery or household supply stores. Borax crystals form quickly if you need fast results. You will need:

  • three tablespoons borax
  • one cup of water
  • cotton string

Follow the basic instructions for alum crystals but use cotton string or pipe cleaners instead of nylon string.

Recipe: Rock candy (for fun):

  • three cups of sugar
  • one cup of water
  • food coloring if desired
  • up to 1 teaspoon of liquid flavoring if desired.
  • cotton string
  • a glass jar

Bring your sugar and water mixture to a boil but do not overheat. Stir your mixture well until all of the sugar is dissolved. You may add food coloring and/or flavors while stirring. Allow your mixture to cool in a refrigerator until it is about 50 degrees F. While the mixture is cooling, hang a string in your glass jar. You can tie your string around a small clean artists paint brush or other item to hold it on top of the jar. When you mixture is cool, pour it into your jar. Cover the jar with a paper towel or coffee filter and allow it to sit undisturbed until the liquid evaporates or you are happy with the size of your crystal candy.

Remember to document your ingredients and all the steps you take in the process of making your crystals and you should have a successful science fair project. If you make candy crystals, you can even enjoy your project when the fair is over.


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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://chemistry.about.com/cs/growingcrystals/a/aa012604.htm
  • InfoBoxCallToAction ActionArrowhttp://chemistry.about.com/od/growingcrystals/a/seedcrystal.htm
  • InfoBoxCallToAction ActionArrowhttp://chemistry.about.com/od/growingcrystals/ht/epsomcrystal.htm
  • InfoBoxCallToAction ActionArrowhttp://chemistry.about.com/cs/howtos/ht/boraxsnowflake.htm