June 2020 Soap Challenge Club Entry: Controlling Trace

The Soap Challenge Club, hosted by Amy Warden, is a group of soap makers who come together to learn new techniques and engage in a little healthy competition each month. Amy shares a tutorial and soap makers have the month to practice the technique, ask questions, share tips, and finally enter a soap for competition

This month’s challenge is called the “one pot wonder”. Cold process soap batter is separated and colored differently, then the different colored portions are layered together in ONE pot and poured into the mold from that one pot. If the soap batter is the right consistency and is poured back and forth down the long side of the mold, light and feathery layers can be seen in the final soap bar.

What is trace in cold process soap making?

Cold process soap making means that we do not add heat to accelerate the soap reaction. In fact, we use various techniques to slow down the soap reaction, keeping the batter fluid longer. This is often called controlling the “trace” of soap batter. Once sodium hydroxide (lye) is mixed with oils, the soaping reaction begins and the batter gets thicker as it turns into soap. The first step in this process is emulsion. Emulsion occurs when the oil and water portion mix together and don’t separate. (This is what soap does- brings oils and water together.) Continuing to mix, soap batter gets thicker and reaches a light trace. When you pull the stick blender or spoon out the soap batter and trail some of the batter over the surface, does it sit on the surface of the batter for just a second before being absorbed? If so, light trace has been reached. Medium trace gets somewhat subjective, but it means that it takes longer for the soap batter trailed over the surface to absorb into the batter in the container. The batter is thicker. Waiting until heavy trace gives you time to maybe get the soap batter in the mold, but little to no time for coloring and scenting the soap batter. The key to success in this "one pot wonder" technique is to slow this process down to have time to separate soap batter into portions to color differently, pour colors as separate layers into the pouring pot, then pour into the mold while the soap batter is thick enough that colors don't mix, but not so thick that it “glops” into the mold. 

How do I control trace?

To keep soap batter fluid longer, many factors are considered. First is temperature. The lower the temperature, the slower the soap reaction and batter remains fluid longer. Mixing sodium hydroxide into water produces a solution that quickly rises to over 180 degrees Fahrenheit! This needs to cool before you mix your sodium hydroxide solution with your oils and butters. Also, once you measure your solid oils and melt them, you want to let your oils cool to room temperature before beginning the soap reaction. Mixing with a stick blender accelerates the soap reaction. Pulsing the blender and mixing to barely emulsion then stopping will give you more time to work this technique. This means that by the time you've mixed your colors and fragrance, your batter will be at a light to light/medium trace. Using a recipe with a slightly higher water content can also slow down trace. Fragrance choice is a major factor to consider when controlling trace. Floral and spicy fragrance notes tend to accelerate trace while minty and fruity notes tend not to accelerate. There certainly are exceptions to this rule and ALWAYS research your fragrance oils before using. Buy fragrances from reputable vendors who provide information as to how fragrances perform in cold process soap making. Adding fragrances after coloring, instead of before, will also give you more time to work with fluid batter. Colorants are another consideration. Clays and oxides may thicken soap batter, while micas usually do not.

If you consider all the above factors and your soap batter still seems to move too fast, consider your recipe. Oils that are rich in saturated fatty acids like lauric, myristic, palmitic, and stearic acids will accelerate trace while unsaturated fatty acids like oleic, linoleic, and linolenic will move more slowly. So pay attention to that fatty acid profile in your soap recipe! In general, oils that are solid at room temperate (like butters) are high in saturated fatty acids, while those that are liquid at room temperature are high in unsaturated fatty acids. You still need a balance, though. You don’t want to produce a soap that is too soft.

The "one pot wonder" challenge:

For this challenge, I soaped at about 80 degrees Fahrenheit. I changed my recipe a little to have more unsaturated fatty acids to slow down trace. To do this, I subbed some of my butters with sweet almond and olive oils. I used a grapefruit and mint fragrance that I worked with before and knew didn’t accelerate trace. I did use titanium dioxide as one of my colorants, but I used only a little and kept color at cream instead of white. My other colorants were all micas. I chose red violet, teal, peachy orange, and cream for colors. I mixed my oils and sodium hydroxide solution just to emulsion, separated evenly into 4 portions, colored each portion, added fragrance, then layered into my pouring pot, trying not to to mix the layers. I then poured along the long edge of my mold, moving the spout of my pouring pot back and forth somewhat rapidly. I tilted my mold at an angle to make this process easier. 

I attempted this soap challenge three times and ended up submitting my first attempt. For all three attempts, my soap batter did remain fairly fluid, but toward the end of the pours, it did get a little thicker than I would have liked. Although I didn’t get the light, feathery layers, I still like my soap entry and had fun with a new technique. I attribute the temperature of my soap studio to this slight acceleration, but there is little I can do about hot Louisiana summers!

You can purchase this soap here. 

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