Posts Tagged ‘salt’

Sweet (and Salty) Lava Lamps

March 3, 2010

Pull out a jar, a bottle of vegetable oil, some food coloring, salt, sugar, and water to mix up this easy experiment! 

Fill the jar about halfway up with water and add a few drops of food coloring for contrast.  Add about half as much vegetable oil to the jar and watch it float to the top.  Now, a spoonful at a time, add salt to the jar.  The salt will pull some of the oil down with it, but will release the oil as it dissolves and the oil will float back to the top.  This will make your science experiment look like a real lava lamp.  Keep adding salt to make it keep working.  Now, try adding sugar or even sand. Kosher salt worked really well!

What worked the best for you?  Do you know why oil floats to the top of the water?  Email me your answers in the comments section at for a chance to win a tee shirt (size M.)  I’ll do a drawing for a winner in two weeks!

Growing Crystals

September 20, 2009


Patience is tough for kids, especially in today’s world of instant gratification.  In this experiment, your kids will put a string in some colored salt water and watch and wait for crystals to grow.  The crystals aren’t huge and spectacular, but your child can see them and a magnifying glass makes them easier to inspect.

All you’ll need is a clear container or containers, water, salt, food coloring and string.  We used both kitchen twine and jute twine to see what would happen.  The kitchen twine is white and worked well, but the jute twine didnt’ work at all.  

First, have your child put a few drops of food coloring in the container(s) that you are using.  Then, have them cut a piece of string about six inches long.  It doesn’t have to be exact.  Help your child tie a knot or two at each end of the string.


Boil some water (a cup or two) and, when it is boiling, start adding salt to the water.  Add a tablespoon at a time, stirring the mixture to dissolve the salt.   Do this until no more salt will dissolve (you’ll see salt and it won’t go away no matter how much or how long you stir.)  At this point, you can let the mixture cool a little so it’s not dangerously hot.


When cool, pour an eighth cup or so of the salt solution you’ve made into the container(s) containing food coloring.  Let your child mix it and then have them place one end of the string into the colored salt solution.  They may have to swish it around to get it to soak up the salt water since the string will want to float.   Leave the other end of the string hanging over the edge of the container.IMG_3309

As the water evaporates, the salt that the string has absorbed will remain in the fibers on the string and form new, larger crystals on the string.  Have your child check the string every day and, if they want to, record the results in their lab notebooks.  It may take several days before the water evaporates and the salt crystals form – it took ours five days to evaporate.  Try not to let the end of the string that hangs over the edge of the jar or glass touch the counter, or the salt water will be wicked onto the countertop.  As I said before, a magnifying glass is a fantastic way to look at the crystals that form on the string.  Ask your child what shape the crystal are-cubes, spikes?  What do they see?  If they’re interested, have them draw the crystals and record their observations. 

There are great books on crystals and gems at the library.  Check them out!