Harry Potter Bath Bombs In Cauldrons – with house reveal!

Our love of Harry Potter around here is far from a secret! So it only makes sense that we continue to come up with ideas that let us indulge our geeky love and proud Potterhead status. This week we decided to create special Harry Potter bath bombs in cauldrons that have a special house reveal, just like the sorting hat. Will it be Gryffindor, Slytherin, Hufflepuff or Ravenclaw? Have a bath and find out!

Harry Potter Bath Bombs in Cauldrons – Bath Bomb Making Project For Kids

Harry Potter Cauldron Bath Bombs

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A few weeks ago we created a whole Harry Potter school plan full of cool educational ideas. Turns out that wasn’t enough for my kids, we needed more magical Hogwarts inspired lessons! So this week we dabbled in a bit of potions (chemistry) and created bath bombs in cauldrons. These are not just any bath bombs though, these are house reveal bath bombs! It was a fun twist that the kids loved in this project.

Want to try another Harry Potter Bath Bomb? Check out our gorgeous Golden Snitch Bath Bomb or our Triwizard Tournament Golden Egg Bath Bomb!

DIY Harry Potter Bath Bomb created to look like a Golden Snitch from Quidditch.

The Potions Lesson – The Science Of How Bath Bombs Work

The best part about this bath bomb project is that it feels like a real potions class! With all the little cauldrons and the many bowls of different coloured potions brewing, it makes for a fantastically real feeling class from Hogwarts. We just need Snape pacing around us, peering down his nose and it would be perfect.

Now, we know Professor Snape would be all about the facts and details. So let’s chat a bit about how bath bombs work.

The magical fizzy of bath bombs is actually the result of an acid-base reaction between citric acid and baking soda. We have done some really cool “potions” classes that explore the reactions between acids and bases, like our colour changing oobleck and pH study. That “fizz and bubbles” is actually Carbon Dioxide gas that is released during the chemical reaction.

So why don’t bath bombs react right away like they do in our other experiments? For the reaction to happen we need to add water. In our other experiments we usually use vinegar as our acid which already has water to activate the reaction. When making bath bombs our citric acid and baking soda (base) are in dry powder form. They can mingle without any reaction. That is until we add the all important… water!

cauldron bath bomb with hogwarts house reveal

Once we add water, citric acid [C6H8O7] and sodium bicarbonate [NaHCO3] (baking soda) react to form sodium citrate [Na3C6H5O7], water, and carbon dioxide [CO2] gas.

Then our magical fizzy bubbles start erupting everywhere and our little cauldrons bubble over!

For a little extra potions lesson, you can explore the role of two more ingredients – Polysorbate 80 and SLSA.

Polysorbate 80 is an emulsifier. We know oil and water don’t usually mix. But with the addition of an emulsifier we can help them blend and dissolve to create a nicer bath experience and helps keep the oils and colours in the water rather than on the sides of the tub.

SLSA (Sodium Laurel Sulfoacetate) is a surfactant that helps create more foam during the reaction which means more bubbles! It also helps prolong the fragrance release so your bath will smell amazing from beginning to end.

Harry Potter Cauldron Bath Bombs

Unlike some of our other bath bomb activities this one is actually fairly easy for younger kids or those with fine motor struggles. With our other bath bomb making techniques we have to be very careful about how we pack the molds. In this bath bomb recipe the cauldron is part of our bath bomb experience. So once kids pack the cauldrons they can just take the whole thing into the bath with them. There is none of the struggle to remove the mold, or worrying about packing it tight enough to ensure it holds together.

However, be cautious when having younger kids help with the powders. I find when the younger kids help, the citric acid powder especially likes to become airborne and can be a bit of an irritant. Kids seem to put lots of energy into dumping the ingredients into the bowl! It is best to make in a well ventilated place and if you have concerns, use respiratory protection. I still find this activity is best with older kids, tweens and teens. But with lots of adult supervision, younger kids can do this too.

Kids bath bomb making activity

Harry Potter Bath Bombs in Cauldrons Supplies

1 cup corn starch
2 cups baking soda
1 cup citric acid
1 cup SLSA (Sodium Laurel Sulfoacetate).
5 tablespoons coconut oil
1 teaspoon polysorbate 80
Optional – glitter and essential oils
Mica powders
1 Large mixing bowl and 8 smaller bowls
Plastic cauldrons
Spray bottle of rubbing alcohol

Milliard Citric Acid 5 Pound - 100% Pure Food Grade NON-GMO Project VERIFIED (5 Pound)Sodium Lauryl Sulfoacetate (SLSA) (1.5 lb (24 oz)) by Earthborn Elements, Resealable Tub with Scoop, Bath Bomb Additive, Gentle on Skin, Long Lasting Foam & BubblesPolysorbate 80 (Solubilser) 125 gramsMica Powder Pure 23 Color(Total 230g) - Epoxy Resin Color Pigment with Spoon - Cosmetic Grade Slime Pigment for Resin Coloring Soap Making, Natural Epoxy Colorant for Paint,Art,Bath Bomb - 0.36oz EachFun Express 12 mini cauldrons + 12 broom pens Harry Potter party or Halloween Party set!Electrik Glitter Biodegradable Body Glitter (5G) (Silver Sand Dollar)

DIY Harry Potter Bath Bombs in Cauldrons with House Reveal 

In a large mixing bowl, add baking soda, citric acid, cornstarch, and SLSA.

In a small bowl add coconut oil, approximately 10 drops of the essential oils of your choice, and polysorbate 80. Blend well. Then add to the large bowl.

Mix ingredients together until the texture of wet sand and the mixture forms a ball in your hand.

Separate the mixture evenly into the 7 smaller bowls.

Add glitter to one bowl if desired, this is your white mix. Then one of each color listed below to one the remaining bowls. So black in one bowl, lemon in another, etc. Here are the names of the colors we used for each house from this set:

Hufflepuff: Black and Lemon
Ravenclaw: Blueberry and Grey
Slytherin: Forest and Grey
Gryffindor: Wine and Gold.

Incorporate color thoroughly into each bowl.

For each cauldron, you will add the darker color of the Hogwarts House first and fill a bit less than halfway, pressing down gently. The lighter color will be added next, again pressing down gently until just under the lip of the cauldron. The white mixture will be on top and pressed down until flush with the top of the cauldron.

When you are ready for your reveal, add warm water to the tub. Drop the cauldron in. The white will foam, then you will see the lighter color, and finally the darker color. From start to finish, this process can take 3 to 5 minutes.

Harry Potter Cauldron Bath Bombs Video Demonstration

We decided to make a quick batch of these on video to show you how they work and how truly easy they are to make. However, once we set up we realize we were missing a few ingredients. But that never stops a true scientist, we simply adjusted our recipe.

I was out of mica colouring, so we used food colouring and only one colour in this demonstration. This means our colours are paler since we could only use 2 drops of food colouring because the liquid colour causes the mix to start reacting.

We also didn’t have any polysorbate 80 on hand, so if you look closely you can see our colours and coconut oil float on top of the water.  BUT, we were still able to do a fun demonstration and record it for you to see the general idea.

Another thing we learned while making this video is that you get better reactions the warmer the water. Hmmmm… I see a bath bomb scientific investigation in our future….


Harry Potter Cauldron Bath Bombs


Save those cauldrons and reuse them to make even more bath bombs, including these fun Pot of Gold Bath Bombs.

Pot of Gold Cauldron Bath Bombs


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