Lava lamp: what the liquid is made of

The liquid in a lava lamp is not just water, as this would not produce the desired effect. Two ingredients are required

This is the composition of the liquid in a lava lamp

Lava lamps were very popular a few years ago. They could be found in almost every living room or teenager’s bedroom. The boom may have subsided somewhat, but the fascination remains. The liquid in a lava lamp consists of these two ingredients:

• A lava lamp contains two liquids that interact with each other. They must have a similar density, but must not dissolve or mix into each other.

• As a rule, a wax or an oil is used, which is colored. This is therefore a hydrophobic liquid.

• The second liquid is usually isopropanol or ethylene glycol. This is a so-called hydrophilic liquid.

• A light bulb is installed under the cylinder containing the liquids. This is not only used for lighting, but also for heating the liquids.

• Initially, the colored wax or oil is located in the lower part of the lamp. However, as it heats up, it becomes lighter than the other liquid and therefore rises to the top in bubbles.

• On reaching the top, the hydrophobic liquid becomes colder and therefore heavier again. As a result, it flows back down again. This is why the bubbles in a lava lamp always rise and fall, creating the typical effect