Alum crystals are among the
quickest, easiest, and most reliable crystals you can grow. Did you know you
can make them glow in the dark by adding a common household ingredient to the
crystal growing solution?
Glow
in the Dark Alum Crystal Materials
- fluorescent highlighter pen (I used yellow, but you
can use another color for different colored glowing crystals. Check to make certain the
highlighter will glow under an ultraviolet or black light. Pretty much all yellow
highlighters glow, as do most other colors. Many blue pens will not
glow.)
- alum (sold as a pickling spice)
- water
Grow Glowing Alum Crystals
Carefully cut open the highlighter
and remove the strip that contains the ink. You may want to wear gloves, since
highlighter can stain your fingers.
Pour 1/2 cup of hot tap water into a
clean container.
Squeeze the highlighter strip into
the water to color it with the fluorescent ink. Discard the ink strip when you
are finished.
Slowly stir in alum, a little at a
time, until it stops dissolving.Loosely cover the jar with a coffee filter or
paper towel (to keep dust out) and allow the jar to sit undisturbed overnight.
The next day, you should see small alum crystals at the bottom of the
container. If you don't see crystals, allow more time. You can let these crystals
grow, though they will compete with each other for material.
Alternatively, you can use one of
these crystals to grow a large single crystal.
Growing
a Large Single Crystal
- If crystals are present, pour the alum solution into a
clean jar. Collect the small crystals, which are called seed crystals.
- Tie nylon line around the largest, best-shaped crystal.
Tie the other end to a flat object (e.g., popsicle stick, ruler, pencil,
butter knife). You will hang the seed crystal by this flat object into the
jar far enough so that it will be covered in liquid, but won't touch the
bottom or sides of the jar. It may take a few tries to get the length just
right.)
- When you have the right string length, hang the seed crystal in the jar with the alum solution. Cover it with
the coffee filter and grow a crystal.
- Grow your crystal until you are satisfied with it. If
you see crystals starting to grow on the sides or bottom of your jar,
carefully remove your crystal, pour the liquid into the clean jar, and put
the crystal in the new jar.
Making
the Crystal Glow
When you are satisfied with your
crystal, remove it from the crystal growing solution and allow it to dry. Just shine
a black light (ultraviolet light) on the crystal to make it
glow. Depending on the ink you used, the crystal may glow under fluorescent
light or sunlight.
You can display your crystal or
store it. You can wipe dust from a display crystal using a cloth, but avoid
dampening it with water or else you will dissolve part of your crystal.
Crystals kept in storage may be wrapped in paper for added protection from dust
and changed in temperature and humidity.
True
Glow in the Dark Crystals
If you want the crystals to really
glow in the dark (no black light), then you stir phosphorescent pigment into a
solution of alum and water. Usually, the glow will remain on the exterior of
the crystal rather than get incorporated into the crystal matrix.
Alum crystals are clear, so another
way to make the crystals glow is to mix phosphorescent pigment with clear nail
polish and simply paint regular alum crystals. This also protects the crystals
from damage by water or humidity, preserving them.
How To Grow
a Borax Crystal Snowflake
Borax Crystal Snowflake Materials
String
wide mouth jar (pint)
white pipe cleaners
borax (see tips)
pencil
boiling water
blue food coloring (opt.)
scissors
Time Required: Overnight
Let's
Make Borax Crystal Snowflakes!
- The first step of making borax crystal snowflakes is to
make the snowflake shape. Cut a pipe cleaner into
three equal sections.
- Twist the sections together at their centers to form a
six-sided snowflake shape. Don't worry if an end isn't even, just trim to
get the desired shape. The snowflake should fit inside the jar.
- Tie the string to the end of one of the snowflake arms.
Tie the other end of the string to the pencil. You want the length to be
such that the pencil hangs the snowflake into the jar.
- Fill the widemouth pint jar with boiling water.
- Add borax one tablespoon at a time to the boiling
water, stirring to dissolve after each addition. The amount used is 3
tablespoons borax per cup of water. It is okay if some undissolved borax
settles to the bottom of the jar.
- If desired, you may tint the mixture with food color.
- Hang the pipe cleaner snowflake into the jar so that
the pencil rests on top of the jar and the snowflake is completely covered
with liquid and hangs freely (not touching the bottom of the jar).
- Allow the jar to sit in an undisturbed location
overnight.
- Look at the pretty crystals!!! You can hang your snowflake
as a decoration or in a window to catch the sunlight.
Tips
for Success
- Borax is available at grocery stores in the laundry
soap section, such as 20 Mule Team Borax Laundry Booster. Do not use
Boraxo soap.
- Because boiling water is used and because borax isn't
intended for eating, adult supervision is recommended for this project.
- You can also try table salt (NaCl) but the crystals may
not form as large or as quickly.