Mr. Zimmerman's Science Class     |     home
What You Need:
1/2 c hot tap water
2-1/2 T alum
nylon fishing line
pencil, ruler, or knife
2 clean jars
coffee filter/paper towel


How to Grow Alum Crystals

Alum crystals form as attractive glasslike squares. Add different shades of food coloring and grow numerous crystals to make a colorful alum-crystal garden.
1.  Heat 1/2 c. water almost to boiling.
2.  Remove from heat.
3.  Pour into a bowl.
4.  Stir in alum slowly. Add in more until the alum is no longer dissolving but is starting to settle at the bottom of the bowl.
5.  Pour a small amount of the solution into another bowl.
6.  Allow to cool. Once cool, you should see small crystals forming.
7.  Take out one of the crystals and allow it to dry completely. This is your "seed" crystal, or the place from which the rest of the crystal will grow.
8.  Tie one end of a piece of thread around the crystal, and tie the other end around the middle of a pencil.
9.  Prepare another solution, repeating steps 1 through 4.
10.  Pour the solution into a glass jar.
11.  Place the pencil over the jar so that the thread hangs down into the jar and the crystal is suspended in the solution.
12.  Place a paper towel over the top of the jar to keep dust from getting into the crystals.
13.  Allow several days for the crystal to grow.
  You can find alum in the grocery store, in the section for spices or canning.
  Make sure to supersaturate your solution. This means continuing to add the alum and stir it in until the solution is saturated, and the alum begins collecting on the bottom of the dish.
  If the thread hanging from the pencil is too long when you place it in the solution, just roll the pencil between your hands until the thread wraps around it and the length hanging down becomes shorter.