It’s time for our last Christmas soap of the season! This one is inspired by the eternal fruitcake—that lump of sherry soaked brick-like substance that appears on Christmas potluck dessert tables every year (it may be the exact same lump, if we’re being honest). I know few people that admit to liking fruitcake, and even fewer that actually make the stuff. (I expect to hear from everybody who likes and/or makes fruitcake in the comments section to prove me wrong).
Anyhow, I thought I’d make a Fruitcake soap to add to world’s supply of dense slices embedded with flecks of green, red, and yellow. The multicolour bit requires a bit more effort, but hey—it’s Christmas, right? It’s also a pretty neat effect.
The coloured bits are soap batch #1; we’ll make it up, and divide it into three parts. Each part will be a different color, and then we’ll pour it and let it saponify for a day or two before slicing them into little cubes and leaving them to age for however long you have.
When you’ve got time to make batch #2, we’ll whip that up and suspend our little colourful cubes in it. Once that’s saponified, you’re ready to slice it, age it up, and pat yourself on your back for getting wrapping up your Christmas soaping!
Per 500g (1.1lbs) oils:
- 1 pinch tussah silk or ½ tsp silk peptides
- 2 tsp sodium lactate (optional—hardens the bars)
- 1 tbsp white white kaolin clay
For the colourful cubes:
- Red iron oxide
- Green chromium oxide
- Yellow iron oxide
For the suspending batch, per 500g oils:
2020 update: Given the irritation potential for cinnamon essential oil, I’d recommend using a cinnamon-y fragrance oil rather than the essential oil. Please refer to supplier documentation for maximum usage rates for the particular fragrance oil you’re using when used in soap/rinse-off products.
First off, you’ll want to decide how much soap you’re going to make when all is said and done. I used a big silicone cake pan I found at a rummage sale for my final mould, which held about 12 cups/2.84L of batter. That works out to a batch of soap with about 1850g oils. I figured that out by punching by formula by percents into SoapCalc, fiddling with the total weight of oils, and noting the “soap weight before CP cure or HP cook” value. Once that weight (by grams) was fairly close to my volume (by milliliters), that was my total batch size. You could also do some fancy-pants cross multiplication, but my fiddling way works, too 😉
I’d recommend a pretty good sized batch—definitely nothing less than 1000g. This is because you’re going to want reasonable amounts of the three colours to work with so you can blend in the colourants with an immersion blender without worrying about splattering yourself with raw soap batter. This whole soap is also a reasonable amount of work, so you might as well get a good batch of gifts out of it. All that said, it’s probably best if you’re a reasonably confident soap maker so you can be sure you won’t stuff anything up and end up chucking a seriously large batch of soap.
OK, so—you’ve got your total batch size decided. Divide it in half. One half will be made first and turned into our wee coloured cubes. The second half will be made later on, to suspend our colourful cubes in.
For the cubes
Use SoapCalc to calculate your final amounts of oils, lye, and water for the colourful cubes batch—half of your total batch.
Follow my standard soap making instructions. Add the tussah silk to the lye water, pulling it apart into smaller bits to encourage it to dissolve. If using, add the sodium lactate to the lye water after it has cooled and stir to combine. If you’re using the sodium lactate I strongly encourage you let your fats and lye water come to room temperate before combining. I haven’t tried using the sodium lactate above room temperature, but I do notice a much, much faster trace than I would usually get at room temperature, and it’ll only get faster at higher temperatures.
Once your soap batter has reached trace, blend in the clay. Then, divide the batter between three small bowls. Make sure the bowls are small enough that the batter is deep enough to submerge your immersion blender in the batter without splattering. Add a wee bit (I used about ¼ tsp of each colour) of green chromium oxide to one bowl, red to another, and yellow to the last.
Using an immersion blender (important! Don’t do this without a blender if you want even, uniform colour), blend the oxides into their respective third of the batch, ensuring you break up all the clods for even colour. You can always add more oxide, so start low and work your way up. Aim for a pastel shade as I’ve found too many oxides can cause glycerin rivers.
Once blended, pour your colours into three different moulds (I used my cavity moulds and ended up with three oval bars of each colour) and let them saponify for at least 24 hours before removing from the moulds and chopping them up into a pile of colourful cubes. I ended up leaving my bars for about two weeks before slicing, which seems ill-advised, but they ended up still being easy to slice at that point, and less sticky than a younger soap would be. My bits were roughly 1cm cubes.
For the suspending batch
Using the same calculations as you did for your cubes batch, measure out your oils, lye, and water. Follow my standard soap making instructions. Add the tussah silk to the lye water, pulling it apart into smaller bits to encourage it to dissolve. If using, add the sodium lactate to the lye water after it has cooled and stir to combine. If you’re using the sodium lactate I strongly encourage you let your fats and lye water come to room temperate before combining. I haven’t tried using the sodium lactate above room temperature, but I do notice a much, much faster trace than I would usually get at room temperature, and it’ll only get faster at higher temperatures.
Once your soap batter has reached trace, blend in the clay, essential oils, and vanilla specks. Now, we need a really thick trace for this batch—think of those pudding cups you might have had as a kid. This soap needs to be thick enough to suspend your cubes, and this can take a while. Once mine reached trace I’d blend some more, and then I prepared my mould. Then I blended some more and went and ate lunch. Eventually, after perhaps half an hour, I had a super thick soap batter. I tested it by dropping a cube in and waiting a while to see if it started to sink.
Now that you’ve got soap pudding batter, stir in all your cubes. It’ll be pretty chunky. Now, to mould! Spoon some of the mixture into your mould a little at a time, knocking the mould sharply against your counter top to knock out any air bubbles as you go. Air bubbles are a big problem with batter this thick, so that’s why we’re doing spoon-knock-spoon-knock-repeat. Once you’ve filled your mould, smooth off the top as best you can (or perhaps do some fancy sculpting if that sounds like fun) and leave your soap to saponify for at least 24 hours. Because my mould was so big and a funny, floppy shape, I left it on my kitchen counter, uncovered, and that was totally fine. I waited closer to 36 hours before removing it from the mould, and then left it for another 36 or so before slicing. This is mostly because I was busy around the 24 hour mark, but it goes to show there’s plenty of flexibility there. Don’t worry if you don’t slice at exactly 24 hours.
Woo! Now all that’s left is letting your fruitcake age for a minimum of three weeks before gifting it. Enjoy and happy holidays!