Bubbling Halloween Slime – Hocus Pocus Slime Making Science

The evil witches of Hocus Pocus would easily love this bubbling Halloween slime recipe! If you are looking for a spooky good time with a family friendly movie theme, our bubbling, fizzing, erupting cauldron of oozing slime is perfect! This incredible homemade slime recipe is easy to make and a hit with the kiddos any time of the year, but who doesn’t want to mix up spell binding potions once in a while.

bubbling slime recipe hocus pocus theme slime making activity

You will be taking Halloween slime making to a whole new level of slimy awesome-ness!

You are definitely going to want a cookie tray to catch this  bubbling and fizzing “potion”. Hands down, this is the best slime making fun we have had together. Why is that?


Because we love anything that fizzes, bubbles, and erupts. This bubbling slime has the definite oooh and aaah factor, but is also super easy to set up. A little messy, this bubbling Halloween slime is going to be a big HIT this season.

Turn on the movie Hocus Pocus and get set to for your own witch’s or wizard’s brewing station. You choose the colors and creepy crawlies.

Plus you get a fun, stretchy slime out of the science experiment! We used our classic saline solution slime recipe with a bit of a twist…


Honestly, what’s not to LOVE about this bubbling cauldron of slime, and I can’t wait to share with you how to set it up…

The recipe instructions and mixing are different then all our other slimes, so I recommend you read through the directions, tips, and tricks before you get started. As always the right slime ingredients paired with the BEST slime recipes is key!

Note: The slime that is produced is fun and stretchy but definitely is not as high quality as our original slime recipe. Of course, making the bubbling, fizzing slime is half the fun. If you want a super awesome stretchy slime without a volcano, check out the original saline slime recipe here.


We always like to include a bit of homemade slime science around here. Slime really does make for an excellent chemistry demonstration and kids love it too! Mixtures, substances, polymers, cross linking, states of matter, elasticity, and viscosity are just a few of the 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 forms this cool stretchy substance. This is called cross linking!

The glue is a polymer and is made up of long, repeating, and identical strands or molecules. These molecules with flow past one another keeping the glue in a liquid state. Until…

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

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

Is slime a liquid or solid? We call it a Non-newtonian fluid because it’s a little bit of both!

SLIME FOR NGSS: Did you know that slime aligns with the Next Generation Science Standards? It does and you can use slime making to explore states of matter and its interactions. Check out NGSS 2-PS1-1 for more information!

Read more about slime science here!

Of course there is an additional science experiment going on here which is the chemical reaction between the baking soda and the vinegar. When the acid and base mix together, they produce a gas called carbon dioxide. This is seen in the fizzing bubbling eruption that takes place when you stir the slime! Continue to explore states of matter too!



1/2 cup Elmer’s Washable White School Glue

1 tbs Saline Solution

2 tbs Baking Soda

1/4 cup White Vinegar

Food Coloring (green or any Halloween colors you want!)

Small Cauldron or Container (for mixing slime)

Small Cup (for mixing vinegar and saline)

Cookie or Craft Tray

Creepy Crawlies


When looking for a good container for your fizzing slime volcano, find something that is on the taller side but with a wide enough opening to allow you to easily mix the slime as well. The nature of a baking soda and vinegar volcano is that the gas produced during the reaction pushes up and out. A taller and narrower container will yield a better eruption compared to a wider and shorter container.

We chose a small black 5″ cauldron for the theme of the slime!


STEP 1: Start by combining the glue and baking soda in your chosen container. You will notice that as you stir the baking soda into the glue it thickens! This is really the point of adding baking soda to saline solution slime recipes.

Go ahead and get witch-y! Throw in all sorts of creepy crawlies!

SLIME TIP #2: Experiment with different amounts of baking soda!

STEP 2: For our bubbling Halloween slime we used green food coloring. Orange and purple would be fun too!

Step 3: In another small container, mix the vinegar and the saline solution.

SLIME TIP #3: You can also play around with the amount of vinegar you use for another way to set up a slime experiment!

Step 4: Pour vinegar/saline mixture into the glue mixture and start stirring!

You will notice the mixture begin to bubble and eventually erupt everywhere! This is the reason for the tray!

Step 5: Continue to stir until the eruption is complete. You will notice that it gets harder and harder to stir because you are mixing your slime as well!

Once you have stirred as much as possible, reach in and pull out your slime! It will be a bit messy at first but this slime is wonderful! All you need to do is knead it a bit.

SLIME TIP #4: add a few drops of saline to your hands before you reach in for the slime!

It should not be sticky on the hands either! But if after kneading your slime it still feels sticky, you can add a drop or two of saline to it and continue to knead. Don’t add too much or you will end up with a rubbery slime!

Go ahead and play with your bubbling slime!

Want more Halloween Science Experiments, click here

What can you do with the leftover slimy eruption on the cookie sheet? You can actually play with it too! We added a squirt of saline to it and had some fun messy slime play. It makes a great popping sound when you squeeze it due to all the bubbles from the reaction that are left over!

As I mentioned above, the slime that is created along with the bubbling Halloween cauldron is not necessarily something that will save for weeks. We found it got a bit watery and not as nice the next day.


Check out even more amazing Halloween slime recipe ideas.

Check out the BEST slime recipes and ideas. See our whole collection here including fluffy slime, cloud slime, crunchy slime, and so much more!


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