Soapmaking is a journey. All along the way, you learn new things, discover various techniques, and perfect your skills. It’s a long-haul trip with something to learn at every turn—and that’s what’s so wonderful about making your own soap!
Luckily, we’ve got several articles and special features to help you navigate these soapy waters. For anyone new to soapmaking, there’s one on how to make your first cold process soaps. For the veterans out there, we have a special feature on the effects of various oils and butters—an indispensable tool for developing your own soap recipes! We’ve also published a vast catalogue of our own recipes, a veritable treasure map that will lead you to unique, fun, and mesmerizing creations.
But we were missing an article on one of the trickiest aspects of soapmaking: trace! While it’s absolutely essential to the success of your soap, it’s difficult to master. How long it takes to reach trace depends on your recipe, and whether you want light, medium, or thick trace depends on what effect you’re looking for. It’s no simple matter! To help you out, we’re dedicating this whole article to trace. Soon enough, you’ll be an expert in trace, ready to set off and explore new horizons.
If you have never made soap before, we recommend starting with our article for beginner soapmakers (see link above). It includes a relatively easy recipe that will help you understand the basics of trace. It also provides you with a lot of useful information that’s best absorbed before going further. Do note however that the last section of this article might be useful for you regardless: it tells you what essential oils to avoid so that you don’t reach trace too quickly. This information will make your life much easier!
If you’ve already made several batches of cold process soap—let’s say at least five, whether or not they all worked out—then you have the knowledge necessary to really benefit from this article. Depending on your experience, some parts may be clearer than others, and that’s perfectly normal. Don’t hesitate to ask us your questions in the comments!
What is trace, anyways?
This mysterious term pops up in every single soap recipe but leaves many soap makers puzzled, even the most advanced ones. Yet, it’s absolutely crucial in cold process soapmaking—at least, if you want your soaps to turn out! Trace is the exact moment when the saponification reaction begins.
So how do you recognize trace? It all has to do with the texture of the soap batter. At trace, the batter is thick enough that gently pulling the wand out of the immersion blender leaves a raised mark on the batter. That’s when you can add your scents, superfatting oil, and exfoliants before pouring your soap into the mold.
It’s crucial for your soap to reach trace, and for saponification to have started, before you pour it. Otherwise, the oils and sodium hydroxide solution may separate, leaving pockets of oil and sodium hydroxide. Reaching trace is especially important as unreacted sodium hydroxide is very corrosive and may irritate or even burn your skin.
The longer you mix the soap batter, the thicker and more visible the trace. You’ll want to play with trace a bit depending on what pattern you want. For making swirled soaps, you generally want to work with a light trace, as we did in our Gravity soap recipe. On the other hand, for embeds or layers, you generally want to work with a thick trace. This will keep the layers separate—like in our famous Glitter in the Gloom recipe!—and will help prevent additions from sinking to the bottom of the soap.
Speeding up or slowing down trace
Now that you know what trace is, it’s time to learn how to control it! You may have already noticed that for some recipes, you’ll have to mix the batter for more than 10 minutes before you reach a light trace, while for others, it will take just a few moments. A lot of factors can affect the speed of trace. Here’s a list of them.
Temperature is key in soapmaking, as you’re probably already aware. While the saponification reaction requires heat in order to occur, it’s also an exothermic reaction, meaning that saponification produces the heat it needs to keep going! That’s why you never need to heat your mixture, except to melt your solid oils and butters.
It’s important to monitor the temperature of your mixtures throughout the whole soapmaking process. You want to work at as low a temperature as possible, meaning you should maintain the temperature around 30–35 ºC, starting from the point when you add the sodium hydroxide solution to the fats in your recipe. Higher temperatures will speed up trace, leaving you with little time to work with the soap, which is not ideal for swirls! Further, if the soap heats up too much, your scents may evaporate or the soap may even overflow your mold.
The tool you use to mix your soap batter will also impact how long it takes to reach the trace. If your recipe doesn’t include any accelerants and you mix it by hand, it will probably take a really long time—you can expect sore arms by the end! That’s why we generally recommend using an immersion blender, which quickly homogenizes the sodium hydroxide solution and oil and butter mixture so that you reach trace sooner.
However, mixing your batter with an immersion blender may cause bubbles to form—you’re making soap, after all. You do want to avoid bubbles and froth if you want a smooth, aesthetically pleasing bar of soap. We recommend turning the immersion blender off from time to time and continuing to mix with it while it’s turned off. You can even use a spatula and the immersion blender at the same time.
Note that if you add any trace-accelerating ingredients, using an immersion blender may cause you to reach trace too quickly. In this case, we recommend mixing with a spatula.
When developing your own recipe, you can play with the concentration of the sodium hydroxide solution by increasing or decreasing the quantity of water in your calculator. If you reduce the volume of water, it will cause the soap to heat up more and accelerate trace.
To make a simple soap, using just one colourant and without any catalysts, we recommend working with a 1.4:1 ratio of water to sodium hydroxide by weight. If you’re making a swirled soap, you’ll need a ratio of 1.75:1. As soon as you add any trace-accelerating ingredient, we strongly recommend that you work with a water to sodium hydroxide ratio ranging from 1.75:1 to 2.25:1.
Oils and butters
For those of you ready to develop your own soap recipe, keep in mind that the fats you choose to include have a huge impact on the final product, affecting hardness, lather, and colour, as well as trace. The more oils and butters you use that are solid at room temperature, the faster you’ll reach trace. If you don’t want to reach trace quickly, solid fats should make up less than 50% of the total weight of the fats in your recipe. For more information on how oils and butters affect the final properties of your soap, remember to check out our article on the topic.
What you include in your soap recipe will have a direct impact on trace. Some ingredients accelerate trace. These ingredients are called catalysts. It’s very useful to keep them in mind when creating your own soap recipe, or when modifying things like scents in an existing recipe! Here’s a non-exhaustive list of ingredients that speed up trace.
Ingredients that contain sugars
- Fruit purees
- Vegetable glycerin
- Wine, etc.
From the beehive
- Dairy milk
- Fermented milk, which is often high in sugar
- Black pepper
- Balsam fir
- Cinnamon bark
- Bay laurel
- Myrrh (10%)
*Note that this list is restricted to the aromatic essences that we sell, because we know their exact composition. If you wish to use an aromatic essence purchased from another shop, check with your supplier about its effect on trace—or test it out yourself.
There you have it! Now you know everything there is to know about trace!