How we did it:
- plastic lids - flat and clear
- cup - (microwave-safe)
- craft stick - (or spoon)
- epsom salt
- pen - (dull pencil)
- hot glue
Carefully cut out the inner circle of one of your plastic covers (yogurt or Pringles lids work well!). Cut as close to the rim as possible. Throw away the rim, but keep the inner circle for later.
In your second plastic cover, use a needle to carefully poke a hole in the rim. You can use a dull pencil or a pen to widen the hole. You will need to fit your string through the hole later.
Make your salt solution. You will need to use the same amounts of water and salt. For example, we used 1 cup of hot water and 1 cup of epsom salt. To heat our water, we put it in the microwave in a microwave-safe cup for 45 seconds. Add salt to the cup and stir for 2 minutes.
When the salt has dissolved, place your second plastic cover with the little hole in a sunny place where it won't be disturbed. Pour your salt solution into the cover. Don't overfill! Then let it sit for approximately 4 days to get a cover full of crystals! You should see some crystals growing in 1 day.
Once your crystals have grown to fill the cover. Carefully hot glue the plastic circle from your first plastic cover over the crystals. Make sure not to crush the salt crystals, they're fragile.
Lastly, string about 5 inches of string through the hole in the rim and tie a knot.
What's going on?
You discovered that Epsom salt creates sparkly crystals as it dries. When you stirred the Epsom salt into the water, the salt didn't disappear. It was just dissolved, or mixed up in the water. Then, as you let your suncatcher sit to dry, the water escaped from the dish into the air. This is called evaporation.
Epsom salt doesn't evaporate, so it got left behind in the dish. As the water started to leave the dish, that left less and less room for the bits of salt to stay dissolved in the remaining water. Little bits of the salted start to fall out of the water -essentially, the salt un-mixed itself from the water! The bits of salt grew together to form the crystals you saw. This is called crystallization.