In this activity , a chance to make some creative cards for the holidays. Earlier this year, Lisa Brindley from our Brisbane CSIRO Science Education Centre (CSIROSEC) told me about a great way to produce a snow effect on home-made cards.
You will need
Salt
Teaspoon
Cardboard (I found dark colours worked best)
A cup, about one-quarter filled with hot tap water.
Cotton buds
A desk lamp with an incandescent bulb (optional)
Hairspray (optional)
Other arts and craft supplies (such as scissors and glue)
An adult
Warning: Hot water can burn. Have an adult help with this activity.
What to do
Dissolve as much salt into the water as you can.
Using the cotton bud, paint the salt water mixture over the areas where you would like to have snow on the card.
Use a thick coating of salt water. When you look at what you have drawn, you should see a ridge of water on the cardboard in the shape you want.
Place it in the sun to dry or you can use a lamp by bringing the lamp within a hands-width (about 10cm) and placing cardboard under it to help dry the water more quickly.
Once the water has dried, you should see a snow effect from the salt crystals.
Finish decorating the card.
You can keep the salt stuck to the paper a bit better by spraying the card with hairspray after it has dried. Make sure you don't hold the spray too close to the cardboard, or the blast might knock some of the salt off.
Tips
Many felt-tip pens and markers use water-soluble ink, so use them after you have made the snow. If you're not sure, test them first.
You can make up stencils of snowflakes or other shapes and use them to produce your designs.
Practice making the snow on some scrap cardboard before doing your final card.
What's happening?
As the water evaporates, the salt (sodium chloride) dissolved in it is left behind as white crystals.
We used hot water for two reasons:
The hotter the water is, the more salt will dissolve in it. By using hot water, more salt will be left behind when the water evaporates.
When the water is hotter, it will evaporate more quickly. The faster the water evaporates, the smaller the salt crystals will be. Tiny crystals help make it look more like snow. Using the sun or a lamp also helps evaporate the water more quickly.
