Rock Soaps

Difficulty: Intermediate
Time: 1 hr
Yields: 6 soaps of about 100 g each

Soap stones, rock soaps, soap pebbles, whatever you want call them, are so much fun to make and they look AMAZING! The marbled look is really easy to achieve, and the variety of colour combinations and shades are endless.

I decided to go for the grey river stone look for these ones, and I used activated charcoal to get the different shades of grey. If you don’t want grey rocks, you can use micas to create different colours, like green, red or even blue rocks. Or you can even mix different colours to create your multicoloured rocks. Feel free and be creative!

The mould I used to make these rock soaps is a special stones mould. The cavities hold about 110 ml each and the cured soap will weigh about 100 g. Any recipe using 500 g oils will work with this mould. The stones are also excellent for the glazing technique (which is an advanced technique), but to be honest, I personally like the marbling with an in-the-pot swirl a lot better, because the marbling will go all the way through the soap and not just on the surface. You can order the stone mould here.

Before starting, please read the safety and precautions post, especially since this tutorial requires the handling of caustic soda!

If you have never made cold-process soap before, I strongly recommend you check out the basic cold process soap tutorial first.

ONE: Prepare your lye as usual and place it in the sink to cool down to room temperature.

I’ve added sodium lactate to the lye solution, to help harden the soap quicker and make it easier to unmould the next day. This is particularly helpful with these kind of moulds, because they are fairly enclosed, making it difficult for the water to evaporate.

TWO: Weigh out your coconut oil and shea butter in a microwavable bowl or jug, and heat it in the microwave until completely melted. In my old microwave it took 3 minutes set on high. There should be no white residue or streaks left visible in the oil. It should be completely clear.

THREE: Once your coconut oil and shea butter are melted, weigh out and add the liquid oils – the olive, sunflower and castor oils.

FOUR: Add your fragrance. I’m using Coconut Lime fragrance from Candlescience, available from Pure Nature in New Zealand, which is one of the most popular fragrances in my soap workshops.

FIVE: Once your lye solution has cooled down to room temperature, and making sure you are still wearing protective goggles and gloves, carefully add the lye to the oils.

SIX: Give it a quick pulse of about 5 seconds with a stick blender and then stir until all the streaks of oil have disappeared and the mixture has emulsified. It should be still very liquid at this stage, you don’t want the mixture to thicken.

SEVEN: Separate the soap into three different portions. Leave one portion uncoloured. Add 1 teaspoon of activated charcoal to one portion and 1/2 teaspoon of activated charcoal to the other portion. Mix with a whisk. Note: you don’t have to disperse the activated charcoal in oil or water beforehand, you can add it direct to the soap, it will mix in easily and without any trouble.

Alternatively, if you don’t want to create grey rocks, you can play with different colours using mica. Again, leave one portion uncoloured, add 1/2 teaspoon of mica to another portion, and 1/4 teaspoon of mica to the last portion. You can either add the mica direct to your soap, and you’ll have a bit of a speckled look in your soap, or you can mix the mica with a little oil before adding for a smooth colour.

EIGHT: Next, pour the three portions of soap back into your main soap jug or bowl, alternating the colours. There is no set way to pour them, and as you can see in the picture above, I just randomly poured the colours into each other. Once you’ve poured all the soap, give it a quick stir with a chopstick, just to give it some extra swirl. Once or two circles is enough.

As you can see my soap is very black when I poured it, but they lightened up significantly the next day.

NINE: Lastly, pour the soap into each cavity of the stone mould, and leave the soap to set overnight.

TEN: Check the following morning if the soap has hardened sufficiently to unmould. If you have used sodium lactate, it will be more likely that you can unmould the next day. Otherwise, you may have to leave the soap in the mould for a few days before it is hard enough to unmould. You don’t want to end up having dents in it from pushing the soap out.

ELEVEN: Leave the soaps to cure for another 6-8 weeks. As with all soaps, the longer the curing time the better the soap will become.

If soap ash develops on your soap rocks, just give them a quick wash. The picture I took below is from a freshly washed soap. The gloss will actually disappear when they dry and they’ll look more like rocks again as in the picture above.

Rock Soaps

  • Difficulty: intermediate
  • Print
Before starting, make sure you wear protective goggles and gloves and work in a well-ventilated area, free from any distractions!


  • 200 g olive oil
  • 150 g coconut oil
  • 50 g shea butter
  • 75 g sunflower oil
  • 25 g castor oil
  • 70 g caustic soda
  • 150 g water
  • 1 teaspoons of sodium lactate
  • 1 1/2 teaspoons of activate charcoal
  • 15 ml fragrance or essential oils


  1. Measure out the caustic soda and the water. Then add the caustic soda to the water  (not the other way round!) and stir until the caustic soda has completely dissolved.
  2. Add 1 teaspoon of sodium lactate to the lye solution. This is to help harden the soap.
  3. Place the lye solution in the sink and let it cool down to room temperature.
  4. Weigh out the coconut oil and shea butter and melt in the microwave or on the stove top until completely melted.
  5. Add the olive oil, sunflower oil, and castor oil to the now liquid coconut oil and shea butter.
  6. Add your fragrance or essential oils to the oils and give it a quick stir.
  7. Once your lye solution has cooled down to room temperature, carefully add it to the oils.
  8. Give the oil/lye mixture a quick 5 second pulse with the stick blender and then stir until all the streaks of oil have disappeared and the mixture has emulsified.
  9. Separate the soap into three portions. Leave one portion uncoloured. Add 1/2 tablespoon of activated charcoal to another portion and 1/4 tablespoon of activated charcoal to the last portion. Stir the soap until the colour has been dispersed throughout.
  10. Pour the three portions back into the main jug or bowl, alternating colours and pouring randomly around the bowl. Once you’ve poured all the soap back, give the soap a quick swirl with a chopstick.
  11. Pour the soap into the cavities of the stone mould and leave to set and harden overnight, or if necessary longer.
  12. Once you are able to unmould the soaps, they will need to cure for a further 6-8 weeks until ready for use.


  1. I love the rocks! I found they look especially nice, when you polish them with nylon pants (panty hose, tights) after they hardened enough. Makes them look really shiny. Try it!

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