Tutorial: Rainbow Linear Swirl Soap Recipe with Natural Colorants

Soapmakers often marvel at all of my rainbow soaps, but often forget that natural colorants can give you a full spectrum of beauty, too! I wanted to show off some rainbow goodness with natural colorants, and the linear swirl soap design technique is the perfect way to do that! (It truly lets the colors shine, plus it's one of the easiest swirls out there!)

Rainbow Linear Swirl Soap Recipe and Tutorial using Natural Colorants and Essential Oils

I'm also trying out a new thing on social media called #60SecondSoaping, where I'll be sharing quick videos of tutorials and recipes that I've made for Modern Soapmaking. We're all crazy busy and busted for time, so why not make the most of your soapmaking video time with quick hits?! Yesssss! I'm totally loving this format, so I'd love to hear what you think!

This linear swirl soap recipe with natural colorants is sized for Brambleberry's 18 Bar Slab Mold. (I use their silicone liner with my own mold box.) You can resize it using a lye calculator for whichever mold works for you. As requested, the formula includes percentages for your convenience in doing so!

(If you aren't sure how much soap your mold holds, you can find out with this guide to resizing your soap recipes to fit your mold.)

Linear Swirl Soap Recipe Used

• 20 ounces Coconut Oil (30% of the oils)
• 14 ounces Apricot Kernel Oil (21% of the oils)
• 11 ounces Olive Oil (16% of the oils)
• 10 ounces Shea Butter (15% of the oils)
• 9 ounces Avocado Oil (13% of the oils)
• 3 ounces Castor Oil (5% of the oils)
• 9.15 ounces Sodium Hydroxide (7% superfat)
• 18.3 ounces Distilled Water (33% lye solution)

I bought these soapmaking oils from Soaper's Choice.

Essential Oil Blend Used

• 45 grams Orange Essential Oil (50% of the blend)
• 18 grams Peppermint Essential Oil (20% of the blend)
• 14 grams Litsea Cubeba Essential Oil (15% of the blend)
• 9 grams West Indies Bay Essential Oil (10% of the blend)
• 4 grams Fresh Ginger Essential Oil (5% of the blend)

These essential oils are from Liberty Natural, but you can use any fragrances or essential oils your heart desires.

Natural Colorants Used

• 1 teaspoon Yellowdock Root Powder (Pinkish Red)
• 1 teaspoon Paprika Powder (Orange)
• 1 teaspoon Turmeric Powder (Golden Yellow)
• ½ teaspoon Nettle Leaf Powder (Green)
• ½ teaspoon Spirulina Powder (Green)
• ½ teaspoon Woad Powder (Navy Blue)
• 1 teaspoon Alkanet Root Powder (Deep Lavender)

PREP WORK: Before diving in, make sure you have all of your ingredients prepped! I measured each natural colorant into its own container (except the nettle and spirulina, they go together!)

I also weighed and measured my oils and essential oils in my main soaping bucket, as well as mixing up my lye solution.

 Prep your natural colorants in individual mixing bowls or measuring cups. Yellowdock, Paprika, Turmeric, Nettle + Spirulina, Woad, and Alkanet!

GET STARTED: This essential oil blend mildly accelerates, so you may want to work with slightly cooler temperatures than normal and minimize the amount of mixing you do with your stick blender. (Want to learn more about controlling trace? I've got you covered!)

Add your lye solution and mix until emulsified. Pour approximately 1 cup of soap into each natural colorant and thoroughly mix the soap into the natural colorant using a whisk or spatula. (Remember, no stick blenders - keep the mixing to a minimum!)

Add your titanium dioxide into the remaining soap in your soap pot, and thoroughly mix. It's okay to stick blend this one a little as you'll be pouring it first!

 Add your lye solution to your oils and get started with your own linear swirl soap!

 Pour about one cup of soap into each measuring container with your natural colorants!

 Make sure to thoroughly mix your natural colorants into the soap, some will mix easier than others.

 Some of the natural colorants will look accurate at this stage, but not all! Don't be surprised by color changes as saponification happens. Check the end of the tutorial to see a comparison of before and after saponification!

 Add your titanium dioxide to the remaining raw soap. I disperse mine before using it!

POUR IT: Start by pouring all of your white soap into the mold as a base layer. This will create a lovely contrast with your natural colorant rainbow on the top of the soap, which makes the colors pop more.

If necessary, you can smooth out the base layer with a spatula to give you a nice even surface to swirl on!

Starting with the yellowdock soap, pour ¾ of the yellowdock soap into the mold using a zigzag pattern. Don't worry about placement! Move on to the soap containing paprika, and then turmeric, etc. Continue pouring the soap with each color, pouring ¾ of each into the mold.

  Pour all of your white soap into your mold to create a base for your rainbow linear swirl soap!

 At this point, you have probably reached a light to medium trace with your soap. It's okay! Don't panic! Just smooth out the bottom layer with your spatula.

 Pour ¾ of each colored soap into the mold, using a zig-zag pattern. Don't worry about precision, this step is a base layer to give the linear swirl a backdrop of color underneath!

 Keep pouring each color until you have poured ¾ of each colored soap into the mold.

SWIRL IT: Starting with the yellowdock soap again, pour the remainder of the soap into the mold using thinner lines and attempting to create a linear placement in the mold. If the soap has gotten too thick to pour thin lines, use a spatula to scoop the soap and drop it in the mold.

Continue pouring the remainder of each color until you have no soap to pour!

Using a chopstick, swirl the top of the soap in a wide 'S' pattern. Start at the far end of the mold from you, drag the chopstick towards you. Make a 'U' shape at the edge of the mold closest to you, and drag the chopstick to the other side again. Rinse and repeat!

 Starting with the yellowdock soap, pour thin lines of colored soap in a zigzag pattern using the remainder of the color. If the soap is too thick, use a spatula to lay down the lines!

 Once you have poured all of your soap into the mold, swirl up the top in a wide 'S' pattern. Drag your chopstick from one side of the mold to the other, make a 'U' and drag back up to the other side of the mold.

FINISH IT UP: Once the soap in the mold loses it's sheen, give it a spritz with rubbing alcohol to prevent ash from forming and cover it up! After 12 to 24 hours, cut and cure the soap!

I highly encourage you to take a peek while the soap is saponifying as watching the natural colorants change is mesmerizing!

When you cut the soap, you have the option of leaving the linear swirl soap top in tact, which gives it a lovely texture. Or you can plane it off with a soap planer to give it a polished and sleek look. Both options create entirely different looks, all created by this one simple swirl!

 Natural colorants in soapmaking can give you quite a scare! This is what the soap looked like in the mold about a half hour after pouring.

 And here's what all these lovely natural colorants look like after saponification! This photo was taken right before I sliced it up!

 The rainbow linear swirl soap recipe with natural colorants, all wrapped up and cut! The soap on the left is the natural texture created by the linear swirl. The soap on the right shows what a linear swirl looks like underneath - you can snag this look, too, by planing your soap tops off!

This rainbow linear swirl soap recipe with natural colorants featured in this tutorial is a cold process general purpose soap recipe. It is palm-free and vegan friendly! It uses a 7% superfat and a 33% lye solution. Feel free to adjust as necessary!