Soap icing and how to pipe soap

Difficulty: Advanced
Time: 1 hr
Yields: 450 g of soap icing

A soap that is used as icing needs to be creamy, smooth and thick enough to pipe, but you also want it to be stable and give you enough time and not start to accelerate or solidify during the piping. It’s not difficult to make soap icing, but there are a few pointers to watch out for.

The two most commonly used piping nozzles are 1M, 2D and 6B. The 1M and 2D nozzles or tips will create the traditional swirl on the cupcakes. The 6B nozzle is called an open star tip or French tip, and has more grooves. You can also use it for swirls, but also to make little icing rosettes or dots. I am using this one below, so you can see what it looks like.

I use a re-usable piping bag, but you can also use disposable piping bags, which are easier to clean up afterwards. Just cut the nozzle from the bag, squeeze out the tip from and rinse it out in hot water. However, one of the big advantages of piping soap is that it’s relatively easy to clean afterwards. Once I have piped my soap, I try and squeeze out as much of the soap as I can from the piping bag, and then I’ll leave it overnight. The next morning, I just rinse it under hot water and the my piping bag is clean! As you can see in the picture above, I have a special piping bag, which I use only for soap making. This is because the piping bag does take on a soap taste after use, and you don’t really want a soapy taste in your edible baking!

If you are new to piping or want to improve your piping skills, here are some videos by CakesbyLynz that you might like. These are normal butter cream icing tutorials, which work great for soap too!

You don’t have to use these on just cupcakes, they look pretty on normal bars of soap too!

Lemon & Poppy Seeds Soap

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


ONE: To prepare the lye, first measure out the water in a heat proof Pyrex jug. Then, in a separate container (I use a little plastic cup for this), weigh out the caustic soda. Make sure you are wearing protective goggles and gloves. Carefully, add the caustic soda to the water and stir until the lye solution is clear.


TWO: In a separate large Pyrex jug or pot, weigh out the coconut oil and cocoa butter. Either heat in the microwave (if using a Pyrex jug) or on the stove (if using a pot), until the oil and butter has completely melted.


THREE: Weigh out the olive oil and sunflower oil to the now-liquid coconut oil and cocoa butter, and give it a quick stir.


FOUR: Make sure you are still wearing your goggles and gloves. When the lye has cooled down to room temperature, carefully add it to the oils and then using a stick blender, pulse and stir until the oil/lye mixture has emulsified (does not separate).

Temperature is quite important here. If you soap too warm, the chemical reaction will accelerate and the soap will thicken too quickly and uncontrollably. Keeping your temperature down will allow you to stay in control of the soap process.


FIVE: Add a teaspoon of titanium dioxide to the soap mixture. I didn’t mix it with oil beforehand, because we’ll be using the stick blender to thoroughly mix it in. I add the titanium dioxide to create a whiter icing, but feel free to leave it out. Instead of titanium dioxide, you can also add other colours if you like.

If you want to add a fragrance, this would be the time to add it to the soap. Make sure the fragrance you use doesn’t accelerate the soap, because it would make it very difficult to pipe! Also, some fragrances, particularly those containing vanillin, will discolour your soap, so keep that in mind when choosing your icing. You wouldn’t want your vanilla icing to turn brown on your cupcakes! I often leave out the fragrance if I pipe only small amounts as decorations, or if the icing goes between two soap slices. The fragrance from the soap will make up for the lack of fragrance in the icing.


SIX: Keep stick blending the soap mixture until it has thickened sufficiently that it will hold its shape when you pipe it.

SEVEN: Scoop the soap into a piping bag with the nozzle attached to it already (you’ll be surprised how often I forget to do this!), and start piping your soap.

Don’t forget that this is still ‘normal’ cold process soap, so it will needs the same length of time to cure, that is at least 4-6 weeks!


Soap icing

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


  • 140 g olive oil
  • 100 g coconut oil
  • 100 g sunflower oil
  • 100 g cocoa butter
  • 60 g caustic soda
  • 120 ml water
  • 1 teaspoon titanium dioxide
  • piping bag and nozzle


  1. Prepare your piping bag and nozzle.
  2. Measure out 120 ml of water in a heat proof Pyrex jug or other suitable container.
  3. Weigh out the caustic soda in a small plastic container.
  4. Add the caustic soda to the water and stir until dissolved. Set aside to cool down.
  5. In a larger heat proof Pyrex jug or pot, weigh out the coconut oil and cocoa butter. Heat in microwave (if Pyrex jug) or stove (if pot) until all the oil and butter has melted.
  6. Add the olive oil and sunflower oil to the now-liquid coconut oil and cocoa butter, and give it all a quick stir.
  7. Once the lye has cooled down to room temperature, and making sure you are still wearing protective goggles and gloves, carefully add the lye to the oils.
  8. Using a stick blender, pulse and stir until the oil/lye mixture has emulsified.
  9. Add the titanium dioxide and then keep stick blending until the soap mixture has thickened enough that you can pipe it.
  10. Scoop the soap into the piping bag (with the nozzle attached!) and pipe your soap.
  11. The soap icing is normal soap, so will also need to cure at least 4-6 weeks until it is ready to use.

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