This beautifully marbled soap is a wonderful example of things not turning out quite how you expected, but being wonderful anyways. My working title for these bars was “Indigo Swirl”, but this batch of soap had different ambitions. The particular level of trace in the batter meant the pour-swirl I had planned ended up turning into wispy, marbley seams of blue rather than dancing swirls, and I couldn’t be more thrilled with how everything turned out.

How to Make DIY Blue Marble Soap

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For this soap I tried something new—a water discount with the intent of eliminating glycerin rivers. When I met Ariane at the Handcrafted Soap & Cosmetic Guild/ Handmade Bath & Body Guild conference in Toronto last June we got to talking about glycerin rivers, and she excitedly told me about a blog post from Auntie Clara about how to prevent them. The general gist of Clara’s discovery is that water discounting means no glycerin rivers, which is fantastic! It’s taken me a while to get around to trying it out, and I figured I’d go all in with a mostly white soap to really test it out. I’m happy to report it worked beautifully! There isn’t a hint of glycerin-river-ing in these bars. Thanks, Ariane & Clara!

How to Make DIY Blue Marble Soap

How to Make DIY Blue Marble Soap

I was thinking these bars would be a bit more on the swirly side, but when I cut them open I was excited to see a beautiful marble-esque pattern. I let the weight of the pour do all the mixing in the mold—I didn’t introduce any kind of hanger or pot swirl—and the end result was thin seams of blue batter that really got tossed around by the white batter, creating a beautiful marbled effect.

How to Make DIY Blue Marble Soap

How to Make DIY Blue Marble Soap

The blue in the batter comes from an indigo infusion; indigo root creates a stunning blue colour that remains stable in soap. I chose an infusion for a smooth blue colour rather than the speckled look that adding the powdered botanical straight to the batter gives. If you don’t have indigo root, feel free to disperse a pH-stable (no ferric ferrocyanide!) blue mica of your choice in some oil and use that instead.

How to Make DIY Blue Marble Soap

How to Make DIY Blue Marble Soap

In addition to the lack of glycerin rivers the water discount gives us, it also creates a loaf that sets up much more quickly than you might be used to. I sliced these at the 24 hour point, which is earlier than I would usually slice soap, and was surprised at how much harder than usual the bars were. I would definitely make sure you make these bars when you know you’ll be available for slicing 24 hours later—don’t make them and then go away for the weekend!

How to Make DIY Blue Marble Soap

How to Make DIY Blue Marble Soap

Ensuring your titanium dioxide is very thoroughly pre-dispersed into liquid oil before adding it to your batter will help prevent those little bright white streaks.

Our scent is all peppermint—it seemed fitting for the cool blue, and seems extra fitting with the marble-like appearance. I love marble (surprise, surprise 😝) for its solemn cool touch, and peppermint seems like a perfect olfactory tribute.

How to Make DIY Blue Marble Soap

How to Make DIY Blue Marble Soap

I’d definitely recommend watching the video for this soap for a much better idea of how the pour happens—it’s a hard thing to describe well. The video also has the cut reveal, which is always rather exciting! In any event, I’m very happy with this fresh marble-y soap, and I hope you like it as well!

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Blue Marble Soap

25% coconut oil
25% tallow (wondering why?)
45% olive oil
5% castor oil

Calculate to 5% superfat with “water as % of oils” at 21.2% (or water to lye ratio at 3:2)

Per 500g fats:

To colour:

Kick things off by calculating out your recipe for the amount of soap you’re making to get the finite amounts of the fats, lye, and water. Unsure about how to use SoapCalc? I made a video to walk you through it! Please ensure you’re familiar with standard soap making procedure before diving in (click that link if you aren’t!).

Prepare your mould—you’ll want a loaf mould for this soap. Melt your oils together in your soaping pot, and have one container with a pouring spout handy (I use these awesome funnel pitchers). Let your oils cool to slightly warmer than room temperature. Mix up your lye water and let that cool to about room temperature (you can use ice for part of your water to speed up the cooling process).

Lay out your work area so you can easily grab your indigo infused oil, and be sure to pre-disperse the clump-prone titanium dioxide in some extra liquid oil so you don’t have to over-blend the batter to smoothly incorporate it. Prepare your mould by lining it, if required.

Now you’re ready to get started! Begin by blending the kaolin clay into the fats. Once that mixture is smooth, add the lye water and bring to a thin trace. Blend in enough titanium dioxide to get a white-ish batter, and then pour approximately 15% of the batter into your secondary container. Add the indigo infused oil to that batter, aiming for a pale blue colour.

To pour, we want our batter to be just on the thin side of a medium trace. Pour one third of the white batter into the mold, then half the blue batter, then one third white, followed by the other half of the blue batter. Top everything off with the remaining white batter, using your spatula to style the top. The pour is definitely best communicated in video form!

Leave the soap to set up for 24 hours (no longer!) before slicing and leaving to age for three weeks before using. Enjoy!

How to Make DIY Blue Marble Soap

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