Pencil lines in soap are thin horizontal lines that are created by lightly dusting a powdered colorant over a layer of freshly poured cold process soap batter, before adding the next layer on top.
They’re a fun and relatively easy way to add visual interest to your soap recipes.
While micas or charcoal, or my personal favorite – cocoa powder, are more commonly used for making pencil lines, I decided to do a little experiment to see how a handful of natural colorants would behave in their place.
Those test results are shown in this article, along with information on each colorant.
First though, just how do you make a pencil line in cold process soap?
1. Mix soap to a medium trace and pour the first layer into the mold.
2. Using a fine sieve or mesh teaspoon (like THIS ONE), lightly sprinkle the powdered colorant over the layer of soap. Depending on the colorant’s texture, you might have to tap it against your hand or the side of the mold a few times to help it get started. For neatness, wipe the extra flecks of colorant off the inside of the mold before proceeding. (Confession: I get lazy and rarely do this.) :)
3. Carefully pour the next layer of soap batter into the mold, pouring low and using a spatula to help reduce the risk of the top layer breaking into the bottom layer.
4. Cover and insulate the soap for 24 hours. When cutting the soap, turn the loaf on its side first, so the colorant doesn’t smear downwards across the front of the bars.
(Photos and directions are adapted from my print book, Simple & Natural Soapmaking.)
My Experiment Making Pencil Lines with Natural Colorants
(Soaps shown have cured almost 4 weeks. See below for updated photos after several months, to compare how the colors held up.)
1. Chamomile Flower Powder (Matricaria recutita) – A gentle herb that’s soothing to skin. As a pencil line in soap, it turned olive green-yellow. I’ll definitely use this again in a future recipe. (Purchased from Mountain Rose Herbs.)
2. Purple Brazilian Clay – A lovely clay naturally colored by minerals in the soil. As a pencil line in soap, it turned kind of a royal purple color that I really like! (Purchased from Bramble Berry.)
3. Indigo Powder (Baphicacanthus Cusia (Nees) Bremek Powder) – A gorgeous natural blue soap colorant that can be a bit finicky sometimes. As a pencil line, it turned a color similar to beet juice and bled into the surrounding layers of soap. It also has a bit of a gritty texture when you rub your finger across it and little bits of it traveled across the bar in spots when cut. My verdict for this one is that I’ll save indigo for adding to the lye solution for blue soaps. (Purchased from Bramble Berry.)
4. Wheatgrass Powder (Triticum aestivum L.) – A pretty bright green powder that’s often used to enrich smoothies. As a pencil line, it turned a dark olive green. It bled into the surrounding layers a bit, but I wouldn’t rule out using it again. (Purchased from Mountain Rose Herbs.)
5. Annatto Seed Powder (Bixa orellana) – A bright orange powder used to add natural yellow or orange tones to soap. As a pencil line, it turned bright orange and bled into the surrounding layers of soap. (Purchased from Mountain Rose Herbs.)
6. Rosehip Powder (Rosa Canina Powder) – Finely powdered rosehips that are full of antioxidants and can be used as a mild exfoliant. As a pencil line, the powder turned a deep dark reddish-brown that reminds me a bit of cocoa powder. I’ll definitely use this one again. (This was kindly gifted to me from Bramble Berry.)
7. Madder Root Powder (Rubia Tinctorum) – This colorant makes gorgeous shades of pink or purple-pink in soap, but as a pencil line it bled into the surrounding layers. The look reminds me a little of a striped peppermint – it might be fun to play with the effect for a Christmas soap. (Purchased from Bramble Berry.)
8. Turmeric Root Powder (Curcuma longa L.) – A super beneficial herb, but also used to color soaps. As a pencil line, it turned kind of a dark mustard yellow-brown which bled into the soap layers a little bit. (Purchased from Mountain Rose Herbs.)
9. Moringa Tea Powder (Moringa oleifera Lam.) – A nutrient rich tea with many health benefits. As a pencil line in soap, it made a dark olive green color that slightly bled into the surrounding layers in spots. Since natural greens tend to fade more easily in soap, I’m waiting to see how the color holds up over the next several months before deciding if I’ll use this one again as a pencil line. I like it so far though! (Purchased from Amazon.)
10. Activated Charcoal (Carbo activatus)- This is a common pencil line ingredient, but to be honest, I just don’t like working with it. It smears and streaks more easily than options like cocoa powder. However, I rarely take to the time to aim for extra neat lines, so if you’re more careful and precise than I tend to be, you can create quite striking lines with charcoal! (Purchased from Bramble Berry.)
11. Cocoa Powder – A common baking ingredient, this can give soap a natural brown color. This is the ingredient I use most often to make pencil lines. (Purchased from my local grocery store.)
12. Chlorella Powder (Chlorella vulgaris) – This is one of my favorite natural soap colorants and also made a nice pencil line in soap. However, it did have a few spots where it behaved similar to charcoal (a bit smeary), so if I used it again, I would do so with more care – I was a little haphazard making these samples. (Purchased from Mountain Rose Herbs.)
So, that’s the results of those 12 colorants used as a pencil line in soap. I definitely plan on repeating the experiment with another dozen natural colorants in the future – stay tuned!
UPDATE: Here are the pencil lines 4 months later (so the soaps are a total of 5 months old):
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If you’re looking for more soapmaking inspiration, ideas and encouragement, I have three separate soapmaking products you may enjoy exploring!
1. My print book – Simple & Natural Soapmaking. This book contains 50 easy, unique soap recipes with ingredients and scents inspired by the herb garden, veggie garden, farm, seaside, forest and more. Every project has a full color photo, plus it also includes a super helpful photo gallery of dozens of soaps made with a variety of natural colorants, information on essential oils and more. Read about it HERE.
2. My course – Soapmaking Success. This course was built as a companion or extension of sorts to my Simple & Natural Soapmaking print book. The recipes are completely different than the ones in the print book and my ebooks. It dives deeper into the topics that soapmakers sometimes find extra challenging or intimidating and is filled with 25+ videos, downloadable pdf guides, printable charts and much more. You can find a full list of the topics covered HERE.
3. My Handmade Natural Soaps eBook Collection. This is a set of several eBooks on making natural herbal and floral soaps, shampoo bars and milk soaps, plus printable charts and reference guides on essential oils and troubleshooting. The recipes and format are different from the print book and course materials. You can learn more about the collection HERE.