A Simple Soap Frosting Recipe

Decorative Soap Ideas For Delicious-Looking Soaps

A Simple Soap Frosting Recipe

Reading Time: 6 minutes

There is a lot of disagreement in the world of soap making over the proper soap frosting recipe. While some use a soap frosting recipe that requires chilling the lye water and whipping the hard oils, others prefer using soap batter that has naturally come to a firm enough state for piping. In this article we will explore decorative soap ideas for embellishing your bars with delicious-looking soap frosting using the second technique, allowing a portion of soap batter to naturally firm up to the correct texture for piping. 

The first soap frosting recipes I tried were of the whipped variety. I found that the finished soap had a lovely, fluffy texture and piped easily with the larger stainless steel piping tips. However, there were occasional pockets of air in the mix that caused the piped soap to abruptly stop coming through the nozzle, or to spatter soap batter as the air was pressed out. It also creates a surplus of dirty dishes, and requires a stand mixer. My experience with using a hand mixer was that the mixer spattered too much to be safe.  

I also found that using sodium lactate in soap was of great benefit in adding firmness that allowed for the soap to pop out of the mold without dents and dings. However, my best recommendation is to use sodium lactate and also freeze the soap before unmolding, to prevent mashing the frosting embellishments. As for the soap ingredients used to make the frosting, I found that I could use the same recipe for both the body of my soap and the frosting without any problems.  

I have noticed that a lot of frosted soaps are very tall and unwieldy to use without breaking into pieces. For this reason, I used a standard 46-ounce recipe for the entirety of the soap — body and frosting. The finished soaps were barely taller than a regular soap bar and much easier to use without having to break into portions. I simply measured out a portion of the soap batter and set it aside to firm up while working with the remainder of the soap.  

To keep this process as simple as possible, I decided to use the Heat Transfer soap making technique. This soap frosting recipe will not require any extra equipment or extra ingredients to produce a scrumptious-looking bar of soap. You can color your soap frosting portion with mica mixed with oil and drizzled into the piping bag, just as you would for regular frosting. Also the same as regular frosting, you can set aside portions of the frosting and color them by blending in your pigments mixed with a small amount of oil to prevent clumping. Pack each color into a separate bag, or create a variegated effect by spooning alternating colors into the bag as you fill it.

One thing that seems to be true of all soap frosting is that the biggest stainless steel piping tips available work the best. Fine piping tips were difficult to force the frosting through, and did not seem to render the fine details as they should. It is also good to keep in mind that if you choose to use a reusable piping bag, it will have to be set aside only for soap use — never again for food. In my testing, I used plastic disposable piping bags with no difficulties. The Heat Transfer soap making technique produced a frosting that was between 90 and 100 degrees Fahrenheit, perfectly comfortable for working by hand.  

Simple Soap Frosting

The Heat Transfer Method of soap making is very simple and easy to learn. Measure out your hard oils – the oils that are solid at room temperature — into a soap-safe mixing bowl. Pour the hot lye solution over the hard oils and mix until they are completely liquified. At this point, the heat has been transferred to the oils, and the temperature of the mixture drops from about 200 degrees Fahrenheit for the fresh lye solution to about 115 degrees Fahrenheit in the oil mixture. With the further addition of the soft oils in your recipe (soft oils are liquid at room temperature), the temperature drops even further to about 100 degrees. By the time the frosting has reached proper consistency, it is even cooler.  

Finished soap loaf with piping. The frosting took between 20-30 minutes to reach proper consistency on it’s own. Photo by Melanie Teegarden.

Soap Frosting Recipe 

  • 10 oz. water 
  • 4.25 oz. sodium hydroxide 
  • 6.4 oz. palm oil, room temperature 
  • 8 oz. coconut oil, room temperature 
  • 12.8 oz. olive oil, room temperature 
  • 4.8 oz. castor oil, room temperature 
  • 1 to 2 oz. cosmetic-grade fragrance oil, use manufacturer’s recommended amount for 2 pounds of base oils.  
  • Optional: 2 tsp. Titanium dioxide dissolved in 2 tsp. Water, for producing a white frosting 

Process soap using the Heat Transfer method. Add fragrance, if using, to the body of the soap, and pour into the mold. Have 10 oz. of soap batter set aside for the frosting, and mix it with the titanium dioxide water, if using. Check on the frosting every 10 minutes to see if the consistency is correct — it should be the same consistency as regular frosting — able to hold firm peaks. 

You can use fragrance oil in the frosting itself, but be aware of vanilla content that may turn brown or fragrance misbehavior that might lead to ricing or acceleration. In other words, use a fragrance oil you are familiar with and know to be well-behaved.  

Before piping the soap onto the loaf base, test piping a few embellishments onto a piece of waxed paper to make sure it is the proper consistency. When consistency is reached, pipe the design onto the body of the soap loaf. Any leftover frosting can be used to fill single cavity molds or can be piped into designs on waxed paper for use as a bonus soap.  

It’s easy to see in this photo that the loaf in the center was piped while the frosting was too soft. The embellishment lacks definition and has a molten appearance. Photo by Melanie Teegarden.

As with most soap recipes, allow the sliced bars to cure for six weeks before use. This ensures proper curing and reduction of water content, leading to a more long-lasting bar of soap. The curing process also leads to a slight lowering of the pH, bringing it closer to that of skin, which means the soap will be milder.  

When slicing frosted soap bars, turn the loaf on it’s side for the cleanest cut. Photo by Melanie Teegarden.

These decorative soap ideas will give you a variety of beautiful soaps that look almost good enough to eat. As such, please be careful around young children who may mistake the soap for baked goods or candy. Enjoy!

Ask the Expert

Do you have a soapmaking question? You’re not alone! Check here to see if your question has already been answered. And, if not, use our chat feature to contact our experts!

I’m trying to figure out how much lye water to add to frosting for soap cupcakes. Everything I’ve tried has failed. Please can you help me? – Rebecca

When making soap frosting, simply use your regular soap recipe and omit the fragrance, which can cause acceleration. Mix in the lye and water per the recipe instructions, there is no difference for frosting. Do not blend the soap batter to a medium or hard trace — a light trace is sufficient. Then set aside a portion of your soap batter for frosting, and continue with the rest of the batter as usual, adding fragrance and color and pouring into the molds. Then, you wait. Check the frosting portion every 5 minutes and give it a stir until the proper texture is achieved. Then fill your icing bag and have fun! The trick to frosting is to be patient and wait for the right texture, then work fast. – Melanie

3 thoughts on “A Simple Soap Frosting Recipe”
  1. Can I use a MP soap base to make an exfoliating body scrub? Should I add more glycerin? How much glycerin for 2lb soap base? How should or could I make it?

    1. I have seen tutorials where MP soap was mixed into sugar or salt to make scrubs.
      They melted base, scented it and mixed it into salt.
      Google melt and pour sugar scrubs or MP salt scrubs.

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