DIY Cupcake Bath Bombs With Soap Frosting

We love getting creative with our bath bombs. Using soap to make truly unique bath bombs creates amazing STEAM activities for your tweens and teens. Plus the creativity and science involved is completely fascinating. Here we tried our hand at some cupcake bath bombs that have a soap frosting topper. They look amazing and create a luxurious bath experience.

Homemade Cupcake Bath Bomb Recipe

DIY Cupcake Bath Bomb Recipe with soap frosting

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What is a Bath Bomb?

Maybe you stumbled onto this article thinking we were making some delicious cupcakes only to discover we are talking about some type of bomb for the bathroom. What the heck? Well a bath bomb is simply a fragrant little creation that when added to your warm bath water reacts into this explosion (more like a fizzy, bubbly reaction, not a real explosion), of bubbly, fragrant fun. Kids and adults alike love bath bombs. We love that they involve some fascinating science and creativity, making them an excellent DIY project for teens.

Are Cupcake Bath Bombs Hard To Make?

These bath bombs are a little more complex to make than our simple bath bombs. The frosting can be a challenge and you will need to work quickly. For this reason I only recommend this bath bomb making activity once you have mastered our other bath bomb with soap recipes like our Winter Storm Icicle Bath Bomb or our Donut Bath Bomb with Soap Icing Glaze. You need to be ready to move forward with confidence to get these bath bombs decorated! But keep in mind, even if they don’t look perfect, they will function just the same in the bath tub and be just as much fun!

Like we have said before, making bath bombs is a process that you will master with practice. Environmental conditions can really affect your mix. If you are working in a humid environment you may experience premature fizzing. Or, if you are like me, and live in a dry climate you might find the mix is a little too dry. If this happens you can add an extra teaspoon of coconut oil to the bath bomb mix. Just add slowly and mix really well. It is easy to over do it.

Due to the colours we chose, this cupcake bath bomb would make a wonderful Valentine’s Day bath bomb or New Years Eve Bath Bomb. Feel free to alter the colours to suit your needs.

DIY Cupcake bath bombs in pink

Cupcake Bath Bomb Ingredients

Bath Bombs

1.5 cups baking soda
1/4 cup cream of tartar
1 cup citric acid
1/4 cup pink Himalayan Epsom salts
1/4 cup coconut oil
2 tablespoons polysorbate 80
10-20 drops each of bergamot essential oil and orange essential oil (or use your preferred oils)
1 tablespoon of light pink mica coloring powder
1-2 teaspoons pink biodegradeable glitter
Spray bottle of rubbing alcohol

Soap Frosting

1/4 cup clear or white melt and pour soap base
3/4 cup whipped soap base
1 tablespoon corn starch
1 tsp vegetable glycerin
Orange and bergamot essential oils
Pink mica coloring powder
Silver and gold candy sprinkles (optional)

Cupcake Bath Bomb Tools and Equipment

1 large mixing bowl
1 microwave safe bowl
Muffin tin
Cupcake wrappers
Piping bag with large tip (since this activity requires that you act quickly, I recommend having one bag per person so you can each apply the icing quickly to the cupcakes)
Disposable gloves (optional but recommended so you don’t dye your hands)
Candy thermometer

Click on the images to find ingredients and supplies for making your own bath bombs.

Sodium Bicarbonate, Baking Soda, by Pure Organic Ingredients, 2 lb, Highest Purity, Food Grade, Eco-Friendly PackagingCream of Tartar (1 lb.) by Pure Organic Ingredients, Eco-Friendly Packaging, All-Natural, Non-GMO, Kosher, for Baking, Cleaning, DIY Bathbombs, MoreCitric Acid - 1 lb USA Made Pure for Bath Bombs - Gluten Free Kosher No GMO's - Verified for Organic FoodsDr Teal's Restore & Replenish Pure Epsom Salt & Essential Oils Pink Himalayan Mineral Soak 48 ozViva Naturals Organic Extra Virgin Coconut Oil, 16 OuncePolysorbate 80, 32oz 1 Quart Jug. Safety Sealed ContainerMica powder – Soap Making Kit – Powdered Pigments Set – Soap making dye – 24 coloring - Hand Soap Making Supplies - Resin Dye - Mica Powder Organic for Soap Molds - Bath Bomb Dye Colorant – Makeup DyeBiodegradable Holographic Chunky Body Glitter, ELECTRIK Rave Festival Eco Friendly Cosmetic for Face Hair Nails (Silver)Clear Glycerin Soap Base- 2lbWhite Soap Base 5 Lb.Unscented Whipped Soap, Fluffy Cream Soap, 4 fl ozNOW Solutions Vegetable Glycerine (Liquid), 16-OunceGreen Direct Standard Size White Cupcake Paper/Baking Cup/Cup Liners, Pack of 500Wilton Elegance Cupcake Liners, 150-Count40 Pieces Silicone Pastry Bags, Reusable Icing Piping Bags Baking Cookie Cake Decorating Bags, Cake Decorating Tools with 8 Pack 4 Sizes, 24 Icing Piping Tips, 6 Standard Couplers, 2 Cleaning BrushKitchenAid KSM150PSER Artisan Tilt-Head Stand Mixer with Pouring Shield, 5-Quart, Empire RedNitrile Exam Gloves - Medical Grade, Powder Free, Disposable, Non Sterile, Food Safe, Textured, Indigo Color, Convenient Dispenser Pack of 100, Size MediumPolder Candy/Jelly/Deep Fry Thermometer, Stainless Steel, with Pot Clip Attachment and Quick Reference Temperature Guide

Making The Cupcake Bath Bombs

Add baking soda, citric acid, cream of tartar and Epsom salts to a large bowl and whisk together.

In a microwave safe bowl melt the coconut oil for a few seconds until it becomes a liquid. Mix in the polysorbate 80 and essential oils. Once it is combined, add to the large bowl and mix everything together.

Add the mica color and glitter. This is where this turns into a very sensory experience! Using your hands, break down as many clumps that may be remaining in your mixture. Use your hands to really mix everything together. You will know when the mixture is perfect when it feels like wet sand and you can press the mixture together in your hands and it stays together.

Now we are ready to make the bath bombs. This step is so simple. Just add cupcake liners to a muffin tin and add a handful of the bath bomb mixture to each cup. Press down gently to pack it in nice and tight. Allow the cupcake bath bombs to harden for at least 24 hours before moving on to the frosting step.

Making The Soap Frosting For Cupcake Bath Bombs

Now we are ready to frost our cupcake bath bombs.

Pull out your mixer. Start by adding whipped soap base and glycerin to the mixing bowl. Fold in the cornstarch, essential oils and pink mica coloring. Keep the mica small, 1 teaspoon or less is plenty. Mix on medium speed for 1 minute.

Next, melt your soap base in microwave safe bowl in 30-minute intervals, stirring after each, until melted. Allow it to cool to 140 degrees or about 2 minutes. Use your candy thermometer to check the temperature.

Start to whip the mixture again on medium speed for 1 minute, slowly adding in the cooled down soap base as you go. Once it is all added, beat it on high until the mixture forms peaks, (like when you make a meringue). This takes about 2 minutes. If your frosting is not stiff enough, add another teaspoon of cornstarch and mix. Repeat until the mixture is nice and firm and has nice peaks.

Add the frosting to your piping bag and pipe frosting onto your cupcake bath bombs.

You must work quickly as the frosting will begin to harden after about 5 minutes. At this point, frosting the cupcakes becomes more difficult.

Finally, add a few colorful candy decorations if desired. We added the gold and silver colored candy sprinkles. These just dissolve in the bath water but make a pretty extra touch.

Let set for 4 hours or until soap is completely hard.

Homemade cupcake bath bombs

Check Out Our Video Making Cupcake Bath Bombs

Storing and Using Homemade Cupcake Bath Bombs

Store your bath bombs in airtight containers. After a few days your soap may harden and come off of the bath bomb base fairly easily. This is not a bad thing. If you keep them wrapped nicely it makes it easier to remove the soap and use it in the tub with your bath bomb.

When it is time to use your bath bomb, fill your bath tub with warm water. Climb in. Now lower your bath bomb into the water and enjoy the bath fizzy fun! It will bubble away filling your bath with fragrance and fizzy fun.

If your soap frosting isn’t already hardened and releasing, once you add it to the bath water and the reaction starts, the soap frosting will lift off so you can use it to clean yourself.

Why Do Bath Bombs Fizz? 

This here is the reason we love making bath bombs. The chemistry behind the fizz and bubbles is fascinating! Bath bomb making is a fantastic way to get hands on with chemistry and learn some real life applications. The creativity is also fantastic. There are so many cool bath bomb designs you can make. Add in the need for being exact with your measurements and ratios, and you have some great math thrown in. Bath bomb making is a fantastic STEAM project for your teens and even tweens.

So what is the science? Bath bombs are an acid base reaction. The dry acid ingredients include citric acid and cream of tartar. The dry base ingredient is baking soda. You can mix the dry ingredients and they will not react. For the chemical reaction to be triggered we need to add water.

Another cool ingredient in this recipe is polysorbate 80. It plays a vital role in bath bomb recipes as the emulsifier. This recipe includes oils which would not normally mix well with water. This means without polysorbate 80 you would end up with a slimy, floating mess on top of your water and sticking to the sides of the tub and yourself. It’s not pretty. Polysorbate 80 makes the water and oils mix creating a colourful, fragrant, wonderful bathing experience. I recommend never making bath bombs without polysorbate 80. The mess is simply not worth it.

DIY Cupcake Bath Bombs with Science Lesson


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