Growing crystals can be fast and easy, and your children get to watch an amazing process that will stick with them for years to come. The trick to fast crystal formation is to supersaturate a water solution with a salt that forms crystals. Cooling the solution helps the salt molecules to settle out and coalesce into tiny crystals that quickly form into larger ones. The process is fascinating for young and old alike.
Choose a Container
Pick two containers. You want something that is not very porous, such as ceramic, glass or Pyrex. Each of the containers should be similar in size and shape. Long, narrow containers will produce a more dramatic display. Clear containers make the process much more visible, and therefore more fun to watch!
Prepare a Solution of Epsom Salts
Although many household products can be used to make crystals, one of the best products that gives almost instant results is Epsom salts (also known as magnesium sulfate). You can find it in the pharmacy section of your local store if you don’t have any on hand.
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Prepare one container by combining ½ cup of Epsom salts with an equal amount of very hot tap water. Be sure not to boil the water. With a clean spoon, stir the solution for approximately one minute. This is your growing solution. Be sure to leave some intact crystals in your container, as they are the building blocks for more crystals.
Cool the Growing Solution
Place the container with the growing solution in the refrigerator to chill, along with a second, empty bowl. The second bowl will be used to create a beautiful tower of crystals later on. To ensure easy removal, place heavy, round weighted base materials in the bottom of the container. Poker chips, metal washers, or broken terracotta are good options. They also make for interesting display pieces when finished.
Build a Crystal Tower
After about two to three hours, very fine crystals will have formed in the growing solution. Once this has happened, gently remove the crystals from the growing solution with a clean utensil. Place the mound of crystals in the second chilled bowl. Use caution, because the base crystals will be extremely delicate. Pour the rest of the growing solution into the bowl, but be very careful not to let any undissolved crystals get into the bowl. They will disrupt the formation of a a solid crystal. Let the bowl sit out at room temperature. Within three hours, there should be a tall crystal mound ready for display.
Always have adult supervision when dealing with hot liquids.
TL;DR (Too Long; Didn't Read)
Applying petroleum jelly around the inside surface of the container will prevent crystal growth from building up on the side of the container, ensuring easy removal.