Today we’re making some fun, colourful Christmas Tree Bath Bombs! I took some decoration inspiration from the top of the Christmas Tree Soap bars pre-swirling, and had a lot of fun playing with mica splatters and scatters after molding up all the bath bombs. The base is really easy to work with—it molds beautifully and fizzes like crazy when you drop one into the tub. These bath bombs make fantastic stocking stuffers, and are also really fun to make with friends. Let’s get fizzy!

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All bath bombs are a dry acid-base reaction that’s just waiting to be triggered. Our acids (pH below 7) are citric acid and Cream of Tartar, and baking soda is our base (pH above 7). I really recommend getting all your ingredients for bath bombs in bulk—while you can buy most of these ingredients at the grocery store, the acids especially get quite pricey if you’re buying food grade, 100g or less at a time.

In order to bind our powder base together so it can be molded we start by mixing in some melted firm butter (I used tucuma) and Polysorbate 80—a solubilizer that will help the tucuma butter solubilize into our bath water so we don’t end up with floating blobs of oil in the tub that are a definite safety hazard when you’re getting out!

After we’ve incorporated the oils we’ll need to add a wee bit of water. The water will let our crystalline ingredients slightly dissolve, and then they can fuse together as they dry. Our water is in the form of witch hazel and 70% isopropyl alcohol, both of which react much less than water does, and dry faster.

When our mixture will hold together when squeezed, it’s molding time! I used a spherical mold from Windy Point, but you could also use a 1/4–1/3 cup measuring cup if you don’t want to invest in anything new. When the bombs are all formed it’s time for a fun mica drizzle! You’ll need to mix your mica with a thin, volatile liquid—something that won’t react with the bombs (so no water), and something that will evaporate quickly. 99% isopropyl alcohol is the most common choice, but I ended up using isododecane as that’s what I had, and it worked beautifully! Have fun with your splattering, set the bath bombs aside to dry for a day, and you are all done! Happy Christmas fizzing!

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Christmas Tree Bath Bombs

Oil phase
16g | 2% Polysorbate 80 (USA / Canada)
32g | 4% tucuma butter

Powder phase
416g | 52% baking soda (USA / Canada)
208g | 26% citric acid (USA / Canada)
80g | 10% Epsom salt (USA / Canada)
40g | 5% Cream of Tartar

8g | 1% balsam cedar fragrance oil (USA / Canada)
or 0.75% fir needle essential oil and 0.25% benzoin resinoid

Witch hazel in a mister, as needed
70% isopropyl alcohol in a mister, as needed

Green & gold micas, pre-distributed in 99% isopropyl alochol or isododecane (USA / Canada)

Weigh the oil phase ingredients into a small heat-resistant glass measuring cup. Melt the ingredients together—both a water bath or short bursts in the microwave will work.

Measure the powdered ingredients into a large bowl and mix them together.

Add the melted oils to the powdered ingredients, stir for a wee while, and then add the essential oil. Blend everything together using a flexible silicone spatula, and then switch to using your hands when the melted oils are no longer hot and you won’t be soaking your hands in essential oils. When you’re done blending the final mixture should be uniform and resemble cookie dough a bit. If you grab a handful of the mixture and squeeze it should hold together a little.

Now it’s time to add just enough liquid to get the mixture to hold together in a mold. Not too much, though, or it will react in the bowl/mold, not in your bath. That’s why we’re using misters (they’ll spread the moisture better) of witch hazel and 70% isopropyl alcohol. The reaction isn’t as vigorous when you use witch hazel and alcohol (with the alcohol being less vigorous), plus the bath bombs dry faster.

Spread your mixture out in your bowl so you have as much surface area as possible, and spritz in some witch hazel—I found I needed 6–8 spritzes of witch hazel. Use your hands to quickly combine, misting and mixing. Once you can grab a fairly good handful of the mixture and it’ll hold together, mix in a few spritzes of alcohol. The final mixture should hold together quite well—you should be able to tap a squeezed handful with your finger and have it hold together.

Mould the bath bombs using a spherical mould. If the bath bombs start to become finicky as you work, that’s likely because the mix is starting to dry out—mist in some more liquid until they become workable again. When you’ve used up all the powder, it’s time for the mica drizzles!

Blend 1g of each mica with about 10mL (2 tsp) of 99% isopropyl alcohol or isododecane. Using a disposable pipette, suck up some of the shimmery liquid and then scatter some drops and drizzles overtop of the bombs. I alternated between green and gold, dropping and splattering pretty randomly for a spotty, droppy, abstract effect.

To use, drop in a hot bath and enjoy! This recipe will make about ten 2″ bath bombs, depending on how many survive molding.

Because these bath bombs don’t contain any water once they dry, they do not require a broad-spectrum preservative (broad spectrum preservatives ward off microbial growth, and microbes require water to live—no water, no microbes!). Be sure to keep them dry to ensure they last as long as possible—don’t let any water get into the container/bag you store them in and they should easily last a year.

Substitutions

As always, be aware that making substitutions will change the final product. While these swaps won’t break the recipe, you will get a different final product than I did.

• As I’ve provided this recipe in percentages as well as grams you can easily calculate it to any size using a simple spreadsheet as I’ve explained in this post. As written in grams this recipe will make 800g.
• You can use  more citric acid instead of Cream or Tartar, but this makes the bombs softer as well as much harder to mold. I would really recommend sourcing some Cream of Tartar—it’ll make your life way easier, and the end product much nicer.
• You can use a different brittle or soft butter in place of the tucuma butter
• You can use a different essential oil blend or fragrance
• The mica splatters are optional