How to Make Pencil Lines in CP Soap {+12 Natural Colorants Experiment}

Shea Honey Layered Soap with Cocoa Pencil Line
Sweet Honey & Shea Layers Soap with Cocoa Powder Pencil Line – pg 105 in my Simple & Natural Soapmaking book.

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.

How to Make Pencil Lines in Soap

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.)

CP Soap Pencil Lines made with Chamomile, Purple Clay, Indigo & Wheatgrass

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.)

Pencil Lines made with Annatto, Rosehip, Madder & Turmeric

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):

how pencil lines in soap look after 5 months

Natural Colorants


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Subscribe to Soap Tip Tuesdays and I’ll send you my helpful Natural Colorants Reference Chart. Each Tuesday, you’ll receive one of my best natural soapmaking tips, recipes, or printables. 

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More Resources

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.

several photos of soap says How to Make Pencil Lines in Cold Process Soap
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  1. Hello Jan, I’m a Belgian Fan of your website. I love making soaps for over 2 Years. I buy your 2 Ibooks « simple and natural soapmaking and 101 easy homemade products «  but I also buy Simple and Natural soapmaking Print Book » because I love Print books. I make 4 recipes of your book and I want to make all of them, they are so pretty and good for the skin.
    Excuse my spelling mistakes but I’m learning english for two years and I’m not young anymore ?. Thank you for all recipes and good tips …..see you soon !

  2. I’m going to start with how much I love your blog! I just descovered your page and I love it! I love the two tone soap with the single pincel line. I have made a couple batches of goats milk soap and always end up with a darker bar. I have never tried titanium dioxide to whiten it, yet. It’s hard to find. Do you know a good place to find either it, or a good alternative to make the soap that white? I should add that we do our best to keep the milk from burning, as well. The recipe also calls for palm oil. I have a hard time finding it too and I also hear that it’s not a very sustainable resource to be using. Can I replace palm oil with Shea butter or avacado oil? I want to make it stay as a hard bar. Thank you for your amazing blog and any help you can give me!

    1. Hi Katrina! I’m so happy to hear that you enjoy the blog! :)
      You can buy titanium dioxide at a place like Bramble Berry, though I personally like Zinc Oxide, since it’s considered more of a natural option:
      Another thing that can help your soap be whiter/lighter is to use the lightest colored oils you can find. For example, if you’re using extra virgin olive oil, it can tint the final color of your soap. (Same with unrefined hemp & avocado, and some unrefined butters if they’re very brown.)
      To make a recipe palm free, you could swap the palm oil directly with something like tallow or lard, or you could use a combination of butters.
      I have an article all about some options for making palm oil substitutions you might find helpful:

      1. Do you have a blog that talks about the recommended percentage threshold amount of each oil in a batch? And what each of those oils do for a bar? I really appreciate all of your help! Thank you again!

        Oh, and I was able to find zinc oxide! I can’t wait to try it!

  3. Hi Jan,
    I have tried the pencil lines a few times, but had problems with the lines weakening the bar and often the top would break off easily. Do you have a remedy for this? Thanks for your help!

    1. Hi Heidi! This can happen if you put the powdered colorant on too heavily, so the two soap layers on either side don’t form a tight enough bond. You want to just lightly sprinkle the powder on the fresh soap batter, then pour the next layer over top.
      Another thing to watch for is that the top layer’s soap batter isn’t so thick it has to be spooned on. It should still be pourable. That should help the layers stick together a little better. :)

  4. Oh this is just fantastic! I LOVE seeing the different colored lines! I have only used cocoa powder so far but now that is all going to change! Jan, you are my favorite blogger!!!! I love your ideas, recipes, illustrations (they are so incredibly helpful to a visual learner like me). Thank you for your wisdom and big, generous, kind heart!

  5. Thank you so much for explaining this technique and going to so much detail about all of the different things to use for making pencil lines, so beautiful!

  6. I’m an extreme newbie to soap making and I just received your book in the mail…I can’t wait to try all the recipes! They look so beautiful! Thank you so much for sharing your knowledge and experiences with us!

  7. I just found your page and want to admit that this is sooo amazing! Thank You for all these simple recipes. I am going to try a soap recipe tomorrow! Love the way you use natural herbs in your recipes!

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