Nothing says Valentine’s Day like hearts and slime. If this is your first time stopping by our site, you will see how much we love making slime. If you have seen our slime ideas before, you know that we just had to share a Valentine’s Day Heart Slime with you and your kids. Slime is cool science and sensory play all rolled into one simple slime recipe.

Best easy Valentines Day heart slime ever! Nothing says Valentine's Day like slime. If this is your first time stopping by our site, you will see how much we love making slime. If you have seen our slime ideas before, you know that we just had to share a Valentines Day Heart Slime with you and your kids. Slime is cool science and play all rolled into one simple to make slime recipe.Pin

How to Make Slime

Slime is an excellent science activity to share with kids, and making slime is much simpler than you might think. Our Valentine’s Day heart slime is perfectly festive for the special occasion. Also check out our Valentine’s Day Science Activities!

Slime-making is even more fun when you add creative themes for special occasion days like Valentine’s Day. We have several slime ideas to share, and we are always adding more. This homemade Confetti Heart Slime recipe is yet another AMAZING slime recipe we can show you how to make.

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Basic Slime Recipes

Our holiday, seasonal, and everyday theme slime uses one of our 5 basic slime recipes that are super easy to make! We make slime all the time, and these have become our go-to favorite slime-making recipes.

The base for any of these slimes uses one of our common slime activators, which include saline solution and baking soda, borax powder, or liquid starch.

Slime Science Information

We always like to include a bit of homemade slime science, too, and that’s perfect for exploring Valentine STEM. Slime is an excellent chemistry demonstration, and kids love it too! Mixtures, substances, polymers, cross-linking, states of matter, elasticity, and viscosity are just a few science concepts that can be explored with homemade slime.

What’s the science behind the slime? The borate ions in the slime activators (sodium borate, borax powder, or boric acid) mix with the PVA (polyvinyl-acetate) glue and form this cool, stretchy substance. This is called cross-linking. The glue is a polymer of long, repeating, and identical strands or molecules. These molecules will flow past one another, keeping the glue liquid. Until…

When you add the slime activator or borate ions to the mixture, it starts to connect these long strands. They begin to tangle and mix until the substance is less like the liquid you started with and thicker and rubberier like slime!

Picture the difference between wet spaghetti and leftover spaghetti the next day. As the slime forms, the tangled molecule strands are much like a clump of spaghetti!

Is slime a liquid or solid? We call it a non-Newtonian fluid because it’s a bit of both! Experiment with making the slime more or less viscous with varying amounts of foam beads. Can you change the density?

Valentines Heart Slime Science Pin

Printable Valentine Slime Project Pack

  • Easy to follow basic slime recipes for fluffy slime, borax slime, liquid starch slime, and saline solution slime.
  • Fun Valentine-themed slime recipes and printable labels for parties!
  • Combine slime and math with easy-to-use printable sheets.
  • Find fun ways to experiment with slime science including science information and key vocabulary.
  • Cool slimy theme activities perfect for centers, early finishers, or classroom party time!

Heart Slime Recipe

This confetti heart slime uses one of our most basic slime recipes: clear glue, water, and liquid starch. Now, if you don’t want to use liquid starch, you can test out one of our other basic recipes using saline solution or borax powder.


  • 1/2 Cup of Elmer’s Washable PVA Clear Glue or White Glue 
  • 1/4 Cup of Liquid Starch
  • 1/2 Cup of Water
  • Valentine glitter and confetti hearts
Make Liquid Starch Slime SuppliesPin


STEP 1: Mix 1/2 cup water and 1/2 cup of glue (mix well to combine thoroughly).

STEP 2: Now’s the time to add glitter and confetti! You can never add too much! Mix the glitter and confetti into the glue and water mixture.

STEP 3: Pour in 1/4 cup of liquid starch. You will see the slime immediately start to form. Keep stirring until you have a gooey blob of slime. The liquid should be gone!

Make slime with kids cool sciencePin

STEP 4:  Start kneading your slime! It will appear stringy at first but just work it around with your hands and you will notice the consistency changes. You can also put it in a clean container and set it aside for 3 minutes, and you will also notice the change in consistency! 

STEP 5: Enjoy your slime!

make heart slime for kids slime sciencePin

Storing Your Heart Slime

For one batch of slime, an 8-ounce deli container works well, but if you want to make slime party favors, you can use condiment containers. Add our free printable Valentine labels for a fun science Valentine!

Slime lasts quite a while. Make sure to keep your slime clean, and it will last for several weeks. Enjoy!!

More Fun Valentine Activities

Click on the photo below for more awesome Valentine STEM activities to try with your kids.

Love making slime? Grab our free slime recipe cards!


  1. Click on black box that says get your recipe here and you will find step by step directions with pictures.

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  4. Sta-flo is another common brand for liquid starch that works fine. If you don’t have access to any, try it with our saline solution slime recipe too.

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  12. Can you make the basic slime the night before a classroom party and have the kids add glitter, confetti, etc?

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