Exploring the Density of Liquids with Salt

This modified version of a lava lamp is definitely one of our favorite cool science experiments! It’s a super fun way for kids to explore the density of liquids using materials you have right in your kitchen.

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Cool Science for Kids: Exploring the Density of Liquids~ BuggyandBuddy.com


We have a lot of cool science experiments for kids on Buggy and Buddy like this Baggie Burst experiment and exploring Colorful Chemical Reactions! I think this exploration of liquid density ranks right up there with our favorites!


With just a few household materials, children can explore the density of liquids and even practice mixing colors in a super fun way! (This post contains affiliate links.)


Cool Science Experiments: Density of Liquids

Materials for Science Experiment

Science Experiment Procedure

1. Fill your clear glass about 2/3 of the way with water.


fill your glass with water


2. Pour vegetable oil into your cup. (You want to create a layer that’s about 3/4-1 inch high.) What happens to the oil after you pour it in your cup? Why do you think this happens?


add vegetable oil


3. Add one drop of food coloring to the cup. What happens to the drop of food coloring? Why do you think this happens?


add one drop of food coloring


4.  Sprinkle salt into your cup and watch what happens!


Cool Science Experiments: Exploring the Density of Liquids


5. Continue adding more salt and observe. (The kids started by doing small sprinkles of salt, then progressed to adding big pinches of salt, and then spoonfuls of salt.)


Cool Science Experiments: Exploring the Density of Liquids


6. Allow time for your child to explore the setup on their own. Lucy (6 years old) wanted to add different colors of food coloring to her cup to see what would happen.


add more food coloring to the density experiment- such a cool way to mix colors


This science activity was a great sensory experiment for Theo, my 3 year old. He loved watching all the movement in the cup and would even stick his finger in the liquids to see what would happen!


Cool Science Experiments: Exploring the Density of Liquids

What’s Going On?

In the beginning of the experiment, the oil settles above the water because it is less dense. When you add salt to the to the cup, the salt sinks to the bottom of the cup since it is heavier than the other two liquids. The salt carries a blob of oil with it. As the salt begins to dissolve in the water, it releases the oil which floats back up to the top.


Cool Science Experiments: Exploring the Density of Liquids- Buggy and Buddy

Be sure to try this similar density experiment– comes with a free printable too!

Cool Science Experiment for Kids: Explore Liquid Density with Sensory Bottles

Want to go even further?

Even more activities to inspire creativity and critical thinking for various ages.

1. Try this Dancing Raisins experiment. How is it similar to the one you just did? How is it different?

2. Explore the density of objects in this simple sink and float experiment.

3. Try this Seven Layer Density Column experiment.

Cool Science for Kids: Exploring the Density of Liquids


Be sure to check out STEAM Kids book and ebook for even more creative STEM and STEAM ideas!

STEAM Kids: 50+ STEAM STEM activities for kids


Cool Kitchen Science for Kids: Exploring the Density of Liquids- fun science activity for preschool, kindergarten, first grade and on up! Science experiment using salt and water that always amazes children!  ~ BuggyandBuddy.com


  1. What an amazing way to learn. Love. Stepping in from Tuesday tots.

  2. This looks so cool! And so pretty! I can’t wait to give it a try.

  3. Loved it!! Tried with our little guy tonight. We added pepper after the salt, which was pretty cool! The pepper floated in the oil and when we took a plastic stick to push the pepper down it stuck to the stick until we pulled the stick back up.

  4. Fun fun fun !!!!!!!!!!!!!!!!!!!!!!!

  5. Anonymous says:

    I tried this and it works! The explanation, however, doesn’t seem thorough enough? Does the Salt make the food color’s density greater, therefore, bringing the color down into the color portion?

    • Glad you enjoyed it and thanks for the comment! The food coloring is water soluble. It will not mix with the oil, but will mix with the water. Since it was added after the oil in small amounts, it remands suspended in the oil and won’t mix with it. (If you squeeze a ton at once- which my son happily tried- it will go directly into the water.) The salt is heavier than both the oil and water, so when it lands onto the drops of food dye, it pulls the dye and blobs of oil down with it into the water where the dye will spread.

      • Thanks for the further explanation. We’re using this for a homeschool lesson and I like being able to answer all of her questions.

  6. Lyli Barnes says:

    Not just for the little ones. I had some bored teenagers here on a Saturday night who really got into this

  7. really cool my kids loved it


  1. […] Explore the Density of Liquids with Salt: You only need a few materials from your kitchen to set up this fun science exploration! My kids came up with all kinds of ideas and predictions while doing this! […]

  2. […] colorful experiment further explores the density of salt vs. water, from a different angle. In addition to water and […]

  3. […] Explore the Density of Liquids. A super fun way for kids to explore the density of liquids just with a few household material in your kitchen! All you need is clear glass,water, vegetable oil, food coloring, salt. Tutorial via Buggy and Buddy. […]

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