In the last several months I’ve gone from bath bomb hoarder to a multiple-bath-bomb-per-bath-user due to my self-made bath bomb boom (say that ten times fast!). I’ve been having so much fun whipping up all kinds of different bath bombs, playing with my recipe as well as different micas and scent blends. There’s a box in my bathroom full of bath bombs that would make 12-year-old Marie’s head spin (12-year-old Marie was known for hoarding a single bath bomb for upwards of a year for a time when it was truly needed—today’s stash is basically unimaginable bounty!). These lovely Lavender Spruce Bath Bombs have joined that box of wonder, and they well deserve the good company, and a good soak in the tub.

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As I’ve been playing with bath bombs I’ve made quite a few that not only fizz, but foam, thanks to the inclusion of a powdered surfactant. However, I’m finding as much as I love the foaming in theory, I’m not crazy about it in practice. Every time I drop a couple fizzy/foamy bath bombs in my tub I’m left coated in foam when I climb out of the tub, trying in vain to splash myself off with more foamy water (I wish I had one of those handy wand thingies in my bath). It’s hardly the end of the world, but I did decide to keep these ones strictly fizzy.

I opted to incorporate some micas and create a multi-coloured bath bomb. Each one has a purple cap on one end, and a green cap on the other (well… most of them—the last few are a bit more motley!). Because of the multiple colours, if you break a bath bomb they’re a lot harder to re-form and keep ’em looking pretty, so I saved any broken bath bombs for the end and created a few, err, “less distinguished” ones from the mixed-up bits. They’ll still fizz beautifully!

I used a 2″ spherical mold from Windy Point, and that made about fourteen bath bombs (or it would’ve, if they’d all survived!). If you don’t have a bath bomb mold, feel free to just use a measuring cup instead. I find 1/4 and 1/3 cup sizes work really well for bath bombs! Simply pack in the mixture, upend the measuring cup, and lightly tap to release.

The final bath bombs are very pretty, smell delightful, and are a great addition to our Lavender Spruce theme. Enjoy!

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Lavender Spruce Bath Bombs

416g | 52% baking soda (USA / Canada)
208g | 26% citric acid (USA / Canada)
76g | 9.50% Epsom salt (USA / Canada)
40g | 5% Cream of Tartar

16g | 2% Polysorbate 80 (USA / Canada) or Olivem 300 (USA / Canada)
32g | 4% tucuma butter

6g | 0.75% spruce essential oil
2g | 0.25% lavender essential oil

2g | 0.25% purple mica
2g | 0.25% green mica

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

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.

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.

Quickly divide the mixture between three bowls; you want one bowl that’s mostly white, and then two smaller bowls to colour—one purple and one green. I’d say you want about 70% white, 15% purple, 15% green. Use the micas to colour the two smaller bowls.

Once the mixture will hold together, it’s time to mold it! You’ll want a bit of purple in one half of the mold, a bit of green in the other half, and then heap on the white to create the middle. 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, leave the finished bath bombs to dry overnight.

To use, drop in a hot bath and enjoy! This recipe will make ten to fourteen 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
• You can use a different brittle or soft butter in place of the tucuma butter
• The micas are optional
• If you don’t have spruce essential oil another bright coniferous oil like fir or pine will work; cedarwood is too soft.