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Soap Experiment: A Yellow Dock Ghost Swirl

Natural Soap Color Kit 1

Kandra shares her knowledge of natural soap colorants in her book, The Natural Soap Color Palette. Available for purchase here and on Amazon.

My first trial with yellow dock (Rumex Crispus) yielded an amazingly lovely and almost neon pink. It was an astonishing color compared to other natural pinks and I almost couldn’t believe that it was real! I put the fresh soaps on the cure rack and kept an eye on them over the next few months. I noticed that the pink seemed to deepen and morph every week. Eventually, the pink completely faded, but in a very odd way. It almost “bled out”. It didn’t just fade, it, well, leaked? off the soap and vanished in dots and specks, while leaving a khaki color behind.

Needless to say, I’ve been intrigued with this herbal colorant ever since. After discussing with a few other soapmakers, I found that some have had the same experiences, while others have had seemingly no issues, and I was not able to determine what the causes were. So, I’ve worked up a small experiment with yellow dock to see if I can find an answer to this little mystery.

Some of the factors that could be causing the odd color behavior are gelled vs. not gelled soaps, and water content. And, that’s what we’re going to play with today, with a little help from Auntie Clara and her amazing Ghost Swirl! In a ghost swirl, we use a higher water content to force a portion of the batter to gel at a temperature when that will not allow the low-water batter to gel (basically, high water soaps will go through a full gel phase at a lower temperature than low-water soap).

You can see the entire process and the final cut soap in the following video. You’ll be able to see the color of the infused oil, the reaction and color change as the lye solution reacts with the yellow dock, and the colors of each portion as they are molded. I’ve also included close ups of the wet soap and just as it was unmolded. It’s an astonishing journey of color changes!

Playlist: Yellow Dock Soap Experiment

Here’s a summary of what I learned from this experiment:

In our yellow dock experiment, only the low-water (un-gelled) soap from the loaf has retained the pink color. Both the low-water and high-water soaps retained some pink in the sample rounds that were not insulated.  This leads me to an initial conclusion that yellow dock will create pink soap if you can avoid a full gel.   

It’s also interesting to note that the rich vibrant pink I remember from my first yellow dock soaps is visible in the area where the two portions of the batters meet.

Clearly, further experimentation is needed (woohoo! Excuse to make more soap!). My next attempt with yellow dock will be to chill the soaps and ensure that the gel phase is avoided. If that goes well, yellow dock will be added to my formulation trials for blending colorants to achieve the elusive natural red! You can see more of my color blending experiments in my book, The Natural Soap Color Palette, available on Amazon.

Happy soaping everyone and be sure to share your yellow dock experiences and insights with me in The Natural Soap Color Group on Facebook!

Mandala Natural Soap

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