Make a Homemade Lava Lamp – With and Without Alka-Seltzer

How to Make a Homemade Lava Lamp
The two way to make a homemade lava lamp use oil and water. One uses Alka-Seltzer while the other uses salt to make the lava move.

Have you ever wanted to make a homemade lava lamp? Lava lamps that you buy use high heat and toxic chemicals, but you can make a lava lamp at home using safe kitchen ingredients. Here are two simple ways to make a homemade lava lamp.

Homemade Lava Lamp Materials

This project results in a non-toxic lava lamp that is safe for kids to make and use. The size of the bottle really does not matter, so just use whatever you have available.

  • 1-liter plastic bottle
  • Vegetable oil
  • Water
  • Food coloring
  • Alka-Seltzer tablets
  • Glitter (optional)

Make a Lava Lamp

  1. Fill the bottle most of the way full with vegetable oil.
  2. Add about a tablespoon of water.
  3. Drip in a few drops of food coloring. If you like, add some glitter.
  4. Break an Alka-Seltzer tablet into pieces and add them to the bottle.
  5. Seal the cap on the bottle.
  6. After the reaction is complete, you can break and add another Alka-Seltzer tablet to make more bubbles.
  7. Feel free to shine a flashlight on the bubbles to add the ‘light’ part of a traditional lava lamp.

I made a lava lamp video of this project so you can see what to expect.

How It Works

Oil has a lower density than water, so normally it floats on top of the water. Food coloring dissolves in water, so it dyes the water. However, you can use an oil-based colorant if you want the oil colored instead. As the seltzer tablet dissolves, it releases carbon dioxide bubbles. This is because Alka-Seltzer contains citric acid and sodium bicarbonate (baking soda). These two chemical react much like baking soda and vinegar and produce bubbles. These bubbles mix the oil and water layers. The lava effect comes from the immiscible liquids separating and returning to their original layers.

Alka-Seltzer Substitutes

Replicate the effect of Alka-Seltzer without the expense by using kitchen ingredients. Here are two simple substitutes:

  • Add two heaping spoons of baking soda to the oil and water mixture. Slowly pour vinegar into the liquid and start the lava.
  • Prepare the lava lamp with oil, water, food coloring, and glitter. Add one spoon of baking soda and 2 spoons of citric acid.

Make a Homemade Lava Lamp Without Alka-Seltzer

You can make a homemade lava lamp without Alka-Seltzer. This version of the project also uses a lot less oil, so it’s more economical.

  • Skinny glass
  • Vegetable oil
  • Water
  • Food coloring
  • Salt
  1. Fill the glass 2/3 to 3/4 full with water.
  2. Add a few drops of food coloring. Don’t make the liquid too dark or you won’t see the lava!
  3. Fill the glass the rest of the way using vegetable oil. Leave a bit of space between the liquid level and the top edge of the glass.
  4. When you’re ready for action, dump a spoonful of ordinary table salt onto the oil. The first bubbles form as the salt sinks and releases air bubbles. Once it reaches the bottom, oil blobs move as the salt dissolves, giving the true lava lamp effect.
  5. Add more salt to repeat the effect.

How It Works

The homemade lava lamp that uses salt works because oil is less dense than water and floats on top of it. Salt is more dense than either oil or water, so it sinks when you add it to the glass. Oil blobs stick to the salt and sink with it. As the salt dissolves, the oil globules stick together and slowly return to the top of the glass.