Lava lamps are awesome and so fun to watch!
Here’s how to make a lava lamp:
Get a clear jar (glass or plastic). It has to be a container with a secure lid. A 64-oz soda bottle will do.
Rinse the container thoroughly with clean water to ensure that all contaminants and impurities are removed.
Now, fill ¾ of the container with vegetable oil. Add water to fill up the remaining space inside the container. Put a few drops of food coloring (your preferred color) until you see that the water solution appears fairly dark. The oil layer will remain separated from the colored water layer.
If you want, put some glitter dust to add some sparkle to your lava lamp. Add a pinch or two of table salt. Do you see the bubbles? Now, shine a flashlight behind your lava lamp and see how it glows!
You can place your lava lamp on your bedside table. Tap it now and then, and watch the strange liquid shapes form and move inside the bottle.
Here’s the science behind this amazing homemade lava lamp: oil is less dense (lighter) than water, so it rises to the top of the container. Table salt, on the other hand, is denser (heavier) than water, so it sinks. But then oil also gets attached to the salt crystals while the salt crystals sink. Salt dissolves in water, and the attached oil blobs do not mix with water. Thus, when the salt crystals dissolve, the oil blobs rush upwards to the top and you see the bubbles.