experiment with salt water and food coloring

Salt Water Density Experiment

How does food coloring react to salt & fresh water.

We love experiments that are no fuss and easy! Paired with our FREE observation lab sheet, how can you go wrong! Your students get to predict what they think will happen, make observations, and then conclude why. This experiment uses simple kitchen items to mesmerize your students. We use this Salt Water Density Experiment while investigating our Earth’s Water Unit since it is an effective at displaying the difference in density between salt and fresh water.

*Don’t miss our Floating Egg Experiment with FREE lab sheets that also investigates the difference in density between fresh and salt water. Wait… there’s more! Discover how the freezing point of salt water and fresh water differ in this experiment, “Does Fresh or Salt water freeze faster?”

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Important Terms and Facts to Introduce

Before conducting the experiment, there are a few things you should cover with your students to create a meaningful learning experience. First, spend time talking about the terms below. We discuss the meaning of salinity and density amongst other terms.

– Density is the amount of mass in a given volume.

– Salt is also called Sodium Chloride.

– Salinity  describes the amount of salt dissolved in water. Saline water is water with salt dissolved in it. 

– Solution is a type of homogeneous mixture composed of two or more substances.

– Solute is a substance dissolved in another substance, known as a solvent .

– Water’s density is 1 g/ml.

Salt Water Density Experiment Observation Sheet

The Salt Water Density Experiment Observation Sheet will guide your students through predictions, observations, and give students a place to write a conclusion. Teacher will need to guide student through the experiment and science explanation.

Gather Materials

The materials list is likely to be found within your kitchen. You will need 2 clear glasses, water, salt, and food coloring. Yes, that is it!

Salt Water Density Experiment Lab Procedures

Make predictions.

We started by filling both glasses up with about 1 1/2 cups of water. To create salt water, we added 2 tablespoons of salt to one of the glasses and stirred until completely dissolved.

Next, the students made their predictions about what they thought would happen when we added the food coloring to each glass. One of mine thought that the fresh water would be lighter in color while the salt water would be darker. Two other students predicted that the food coloring would produce bubbles in the salt water.

Make Observations

The first glass we put food coloring into was the fresh water. We only put 3 drops of blue food coloring in. There is no need to stir. This is the optimum time to just observe and then draw your observations. You will notice that the food coloring drops went to the bottom of the glass.

Next, we added the drops of food coloring to the salt water. As you can tell from the next photo, it immediately stopped when it hit the saline solution. It stayed in a layer above the salt water.

Draw Conclusions

the kids and I talk about why they think the food coloring reacted the way it did. In the end, we discuss how salt added mass to the density of the water causing it to become more dense. The density of water is a little less than 1 g/ml. So, if something sinks in water, like the food coloring, it is more dense. If something floats on a liquid, like the food coloring in the salt water glass, it is less dense. 

What I find interesting though, is that if you wait thirty minutes or so, the food coloring in both glasses will disperse. This is because the density of all of the liquids are close enough that the water molecules will eventually collide and join. Liquid molecules move and slip past each other. Pretty cool, huh?

DOWNLOAD Salt Water Density Experiment Observation Sheet

More free resources.

John 4:14  – But whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life.

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Salt Water Density Experiment

Introduction: Salt Water Density Experiment

Step 1: Materials

Step 2: Procedure

Step 3: Additional Ideas and Resources

Extension/Modification Ideas:

• Use a triple beam balance of electronic scale to teach or practice that skill
• Use hot and cold water instead.
• Compare salt and fresh water and connect with the environment.
• Have older students teach this to younger students.
• Use other liquids to make density columns. (Water, oil, alcohol, etc.)
• Make a much larger one as part of a science night.
• Let students try making different density salt solutions and try to figure out which ones work the best and how that relates to density.

Other Density Demos:

• Egg in salt water or tap water
• Ice in water or rubbing alcohol

Attachment: I attached a Word document that is a template for a guided lab report that you feel free to modify and use. Other Ideas and Resources: These are just some ideas and alternate extensions. Some additional references will many different versions of this same idea: DENSITY: SALTWATER COLUMN LAB TEACHER PREPARATION Explains a different way to prepare solutions and some "discussion" questions as a worksheet for students Liquid Rainbow Written from the standpoint of ocean science for elementary school. Contains a lot of "teacher lingo" (e.g. key concepts, big idea, objectives, etc.) GEMS: Discovering Density book This book costs $18, but I think is where I first saw the idea for this lab. The handouts are free online in Spanish. So that might make this a cool activity to do with students learning Spanish too! Steve Spangler 7-Layer Density Column This link provides a video showing a different density experiment with different types of liquids to see how their relative densities are different. They do use the word "heavier" instead of density. He uses a slightly different way of layering. NOAA Lesson Plan: Hot, Cold, Fresh and Salty Another Earth Science/Oceans connection. This lesson plan gives ideas about having students compare hot and cold water and fresh and salty water. These are extensions that would be great to add to a simpler lesson like the one I posted.

Step 4: Real World Connection

In research labs, human blood is carefully pipetted to form a layer on top of a substance called Ficoll-Paque (made by GE). When this tube is centrifuged, the red blood cells (the most dense) go to the bottom, the Ficoll is (the next most dense), then the white blood cells, and finally the plasma (the least dense). Labs use this technique to isolate different parts of the blood. For instance, if you want to isolate the white blood cells, you can remove the plasma layer (yellow) and then gently extract the thin cloudy white layer that contains the white blood cells. Wikipedia's Ficoll-Paque Article This page describes the basics of Ficoll Ficoll-Paque PLUS Manufacturer's Description A short paragraph from the manufactures that uses the word density multiple times Ficoll-Paque Instructional Video This video shows the layering of blood on top of the Ficoll very slowly and gently and the final layers that form

Step 5: Graphic Organizer Word Document

Someone let me know the Word document does not open currently. I tried uploading another version but it also says forbidden. Message me and I can try to send it to you.

Salt and Fresh Water Experiment

It is warm outside and kids are going to the beach (where there is salt water) and the pool. Some kids may notice that they float better in salt water than in fresh water. After doing this experiment, your child will know why this occurs. Explore the difference in density between salt water and fresh water with this easy experiment. 

Let’s Get Started!

• 2 Glasses of Water
• Food Coloring

• Place a few ice cubes into one glass of water

• Add a few drops of food coloring into the ice water.

• Add several tablespoons of salt to the other glass of water and stir so it dissolves.
• Add some ice cubes to the salt water glass.

• Add food coloring to the salt water and see what happens.

• Compare the food coloring in the fresh and salt water.

Why it Works:

• Saltwater is denser than fresh water because the sodium chloride is dissolved in it.
• Specific amounts of salt water is heavier than the same volume of freshwater.
• When salt is dissolved in water, like at the ocean, the salt adds to the mass of the water.
• The salt makes the water denser than it would be without the salt.
• When salt is dissolved in water, as it is in ocean water, it adds to the mass of the water and makes the water denser than it would be without salt. Because objects  float better  on a dense surface, they  float better  on  salt water than in fresh water.

Have fun with this experiment!

Don’t forget to check our two books, Teach your Toddler to Read Through Play and Fun and Easy Ways to Teach your Toddler to Write.

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20 thoughts on “ Salt and Fresh Water Experiment ”

Definitely a great science experiment! Something great for the kids to do during this summer!

Thank you Estefany for the comment. Yes this is simple and fun!

We LOVE experiments like this. This one looks fun and easy to do with things I already have. Thanks!

OH great! I love easy and fun experiments as well. I hope your kids enjoy it. Thank you for commenting Charlene!

My kids are going to love this experiment! It looks like so much fun! Can’t wait to try it out!

Oh great! I do hope your kids enjoy it! It was so simple and fun!

What an amazing experiment on density for kids! You rocked it mama! Thanks for sharing.

Thank you Tam for the comment and compliment!

This is such a great experiment, i better freeze up a bunch of ice cubes fro this weekend. My girls will love this!

Oh great! I hope your girls have fun with this! Thank you for commenting.

This is so easy. My girls would love it. Saving it for my summer activities. Thanks for sharing.

No problem! I love fun and easy activities! Thank you for commenting.

Such a great experiment! We did a similar freshwater/saltwater experiment like this (but with eggs), with our science camp kids, and it was a hit!

This would be cool to do with eggs. My son and I will try this soon. Thank you!

This is such a fun activity with the kids!

Thank you for your comment Mansi!

Hello! I LOVE this for my students, you wouldn’t happen to have a lab sheet to go along with it, would you? Thank you!

Hello Nichole, I am sorry. We don’t have a lab sheet for this experiment. Thank you for your comment. I am glad you like this experiment.

why do you need ice in the water?

Hello Alysha, you don’t need ice. We always put ice in our water.

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Salt Painting For Kids

Raised salt painting with glue and watercolor is an incredible STEAM project because it combines art and chemistry. Kids can explore how salt absorbs water and spreads color. Join us for easy hands-on STEAM activities !

Easy Salt Painting Activity

Raised glue and salt painting with watercolors or food coloring is an excellent STEAM project for kids  because it seamlessly integrates science and art .

On the scientific side, the magic of this project lies in the reaction between the salt and the liquid colors. Kids explore absorption, crystallization, and the dispersion of pigments as the liquid interacts with the salt, providing a hands-on basic chemistry and physics lesson.

💡 What is STEAM? Learn more here.

• PVA school glue or craft glue
• Food coloring (any color of choice)
• White card-stock or watercolor paper (heavier the weight the better)
• Template for your shapes

💡 Recommended Grade Level: Preschool through elementary grades, particularly kindergarten to 2nd grade. However, it can be adapted for older elementary students by incorporating more complex designs or combining them with a lesson on the science of salt absorption.

How to Make Salt Painting Projects

You may want to do this activity in two stages to allow the salt and glue to dry before adding watercolor.

STEP 1: Trace your template onto cardstock.

💡 Stiff paper is recommended for your raised salt painting instead of computer paper or construction paper because it will get a little messy and wet. Look for mixed media or watercolor-type paper!

STEP 2: Add glue to outline your shapes.

STEP 3: Then add a good amount of salt onto the glue and carefully pour the excess salt  off.

STEP 4: Let the glue and salt dry.

STEP 5: Mix a few tablespoons of water with your choice of food coloring to make your watercolor paint.

Salt Painting Tip: The more food coloring you use, the darker your “paint” will appear.

💡Use watercolors instead of our simple food coloring and water mixture below!

STEP 6: Use a pipette to drip the watercolor mixture onto the salt slowly. Try not to drench the patterns but rather watch the salt soak up one droplet of color at a time.

Notice how the water is absorbed and slowly moves throughout the pattern. You can even add drops of different colors and sees what happens!

Leave your salt painting to dry overnight!

Salt Painting Science Info

When watercolor (or liquid food coloring/water) is added, the salt absorbs the liquid. It spreads the pigment along the glue lines, demonstrating capillary action , where liquid moves through a porous material. This project also subtly explores the idea of absorption , showing how different materials interact with water.

Ordinary table salt absorbs moisture from its environment. Its ability to absorb water is what makes salt a good preservative. This property of absorption is called hygroscopic . 

Hygroscopic means salt absorbs liquid water (the watercolor paint mixture) and water vapor in the air. When you do your salt painting, notice how the salt absorbs the watercolor mixture without simply dissolving.

Can you use sugar instead of salt for salt painting? Is sugar hygroscopic like salt? Why not try sugar on your watercolor painting for a fun science experiment and compare the results using the scientific method ?

More Salt Activities

For more fun variations, check out …

• Snowflake Salt Painting
• Ocean Salt Painting
• Leaf Salt Painting
• Grow Salt Crystals

More Fun STEAM Activities

• Coffee Filter Flowers
• Tie Dyed Paper
• Rain Painting
• Paper Sculpture
• “The Dot” STEAM Activities
• STEAM Books for Kids

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

💡 Bonus STEAM Project Pack:  Art meets science with doable projects!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
• Bonus STEAM Project Pack:  Art meets science with doable projects!
• Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics

One Comment

Any reason to not use clear glue?

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Exploring the Density of Liquids with Salt

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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.

Follow our Science for Kids Pinterest board!

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.)

See it in action here!

Cool Science Experiments: Density of Liquids

Materials for science experiment.

• Clear glass
• Vegetable oil
• Food coloring

Science Experiment Procedure

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

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

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

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.)

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.

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!

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.

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

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.

Chelsey was previously an elementary teacher for 12 years and is now creating, playing, and learning at home with her two children. You can follow Buggy and Buddy on Twitter or Facebook by clicking on the icons below.

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