With everything that’s been going on in the world for the last year, it’s been quite a while since I’ve been to a proper spa, but these DIY French Spa Bath Salts make for a fantastic at-home spa experience. They smell just like a proper, luxurious spa and transform your bath water into a silky, fragrant treat. Swoon!

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Being bath salts, the bulk of this product is… salt! I’ve used four different salts. The bulk of the salt blend is velvet French Gray Sea Salt. It’s super smooth, fine salt—almost more like flour than salt. It feels surprisingly creamy, and dissolves very quickly when added to baths. Up next—Epsom salt for soothing sore muscles, and then some plain ol’ sea salt. You can play with the salt blend a bit, but make sure you keep the grain size of the salts fairly small so they dissolve in the bathwater and you don’t end up feeling like you’re sitting on gravel in the tub.

The fourth salt is dendritic salt, which is a special high surface area salt. While it looks like regular table salt to the naked eye, that high surface area makes it extra awesome and a key ingredient when creating free-flowing bath salts. Dendritic salt boosts fragrance retention and prevents clumping, meaning our bath salts don’t fuse into a bath brick in their jar after sitting on a shelf for a while. I consider that to be a pretty essential characteristic of bath salts, which makes dendritic salt an essential ingredient. To learn more, please refer to the Humblebee & Me DIY Encyclopedia.

I’m using Brambleberry’s new Frosted sea glass fragrance to scent these bath salts because oh my, it smells just like an expensive spa. It’s fresh and green, with notes of humidity and moss and clean seaside air. Brambleberry describes it as “a fresh mix of bergamot, lily of the valley, dewy greens, water, ozone, lavender, eucalyptus, cedarwood, oakmoss, resin, and musk.” You could use something else that you love, but if you love fresh, spa-like scents, you might want to give this fragrance oil a try.

Making the bath salts are easy; massage the wet things (the fragrance + solubilizer) into the dendritic salt with gloved hands, and then blend in the rest of the salts. You will need to spread the salts out and leave them to dry for two or three days before packaging, but that’s about it. It’s really simple!

Relevant links & further reading

• Dendritic Salt in the Humblebee & Me Encyclopedia
• Polysorbate 80 in the Humblebee & Me Encyclopedia
• Different solubilizer type things
• Popping Cocoa Coconut Bath Salts
• Lavender Oat Foaming Bath Salts
• How long will ______ last? What is its shelf life?

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French Spa Bath Salts

25g | 10% dendritic salt (USA / Canada)
1.25g | 0.5% Frosted sea glass fragrance
2.5g | 1% Polysorbate 80 (USA / Canada)

71.25g | 28.5% Epsom salt
62.5g | 25% fine sea salt (USA / Canada)
87.5g | 35% French grey sea salt (velvet)

Weigh the dendritic salt, Polysorbate 80, and fragrance into a bowl. Mix together with gloved hands until uniform. Add the rest of the salts, and massage together until uniform.

Spread the mixture out on a cookie sheet and leave it to dry for two or three days before packaging. I used a pretty apothecary-style jar with a cork top and wooden spoon from YellowBee. To use, add a few tablespoons (or more—it’s up to you!) to a running bath and enjoy!

Shelf Life & Storage

Because these bath salts do not contain any water, 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!). Kept reasonably cool and dry, these bath salts should last two or three years.

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 250g.
• To learn more about the ingredients used in this formulation, including why they’re included and what you can substitute them with, please visit the Humblebee & Me Encyclopedia. It doesn’t have everything in it yet, but there’s lots of good information there! If I have not given a specific substitution suggestion in this list please look up the ingredient in the encyclopedia before asking.
• You could try Natrasorb instead of dendritic salts. I really recommend including something that’ll help keep the bath salts from seizing into a solid lump.
• Polysorbate 20 should work instead of Polysorbate 80.
• You can play around with the salt blend, though you may need to re-test the finished product to ensure it doesn’t seize.
• You could use a different bath-safe fragrance oil.