How to Swirl Soap using Natural Colorants

Tips for swirling soap with natural colors including the best soap recipes to use, videos of swirling techniques, and recommended natural colorants.

Swirling cold-process soap with natural colors is a technique that not many soap makers do. It’s more unpredictable than when using conventional colors, the color palette is more limited, and it isn’t easy to achieve vibrant tones. Where there’s a will, there’s a way, though, and I’d like to share some tips for swirling soap with natural colors. Use them to successfully create colored swirls in your bars using plant-based ingredients such as leaves, roots, and spices.

Making Naturally Colored Soap

As a natural soap maker, I tend to make simple, single-colored soap recipes. Sunny yellow carrot soap, soft-purple alkanet soap, and steel-blue woad soap. These recipes are all relatively easy to make, even if some of the ingredients and steps are a little different from standard soap recipes.

Though it would be straightforward to make layered soap with them, up until now, I’ve not introduced any ways to create swirls. That’s because most of my recipes are for beginners. If you’re planning on swirling soap with natural colors, you should be very comfortable with cold-process soap making and identifying the different stages of ‘trace.’ If you’re just starting out, check out my free four-part series on natural soapmaking for beginners.

Swirling Cold-Process Soap

Swirling cold-process soap is an intermediate to advanced soapmaking technique when using conventional soap colorants. Using natural colors makes it even more tricky, and if you’ve made any of my recipes, you’ll soon see why. First of all, I water-discount almost all of my recipes to ensure that you don’t get soda ash. It also speeds up tracing.

Many of my recipes have most of the liquid oils infused with a root of some kind, or an ingredient like turmeric is added directly to the lye water. That means that the entire base color of the soap is colored to begin with. Laying any additional colors on top can create muddy tones unless it’s well-thought-out.

The ideal situation for swirling is a light-colored base soap recipe that traces slowly so that you can divide it up, color the portions, then mix to create beautiful swirls. To swirl, you use various techniques that can involve towers, hangers, skewers, pouring methods, and all kinds of creativity.

Natural vs. Artificial Soap Colorants

If you’ve ever seen cold-process soap swirled in vibrant turquoise, bright red, or neon yellow, the colors are most likely artificial. I don’t use these lab colors personally, but the shades they create are stunning. Though they are dyes, they don’t dye your skin and are considered safe for personal care.

Brightly colored swirled soap could also have been made by using mineral pigments such as oxides and ultramarines. I do use these, but they are considered nature-identical, rather than entirely natural. They’re the color, along with micas, that are used to make mineral make-up. Some micas will color-morph in cold-process soap so be aware if you want to experiment with them.

Natural Colorants to use in Swirling Soap

If you want to be a purist and make 100% natural soap, you’ll need to stick with natural soap colorants such as plant parts and oils, sugars, and clays. Each will need mixing in different ways and quantities into soap, but here are some that I recommend:

• Activated charcoal, powder (steel-blue to black)
• Alkanet root, powder (pale to dark purple)
• Annatto seeds, infused into a carrier oil (yellow to orange)
• Clays, powders in various colors (pink, blue, gray, brick-red, brown, green, purple)
• Cocoa powder (brown)
• Coffee granules, mixed into a little water (light to brown)
• Dried herbs, to leave swirls of herb speckles (brown to black)
• Dried tea, to leave swirls of tea speckles (brown to black)
• Indigo extract, powder (light to dark blue)
• Madder root, powder (pink, mauve, magenta)
• Paprika, powder (pink to orange)
• Spirulina, powder (grey-green)
• Turmeric root, powder (yellow, orange, to brown)
• Woad extract, powder (light to dark blue)
• More ideas for naturally coloring soap

Swirling Cold Process Soap with Natural Colors

Natural colorants that begin as powders are easier to make vibrant or dark swirls than those that aren’t. For example, you can infuse madder roots into oil and use a small amount of that oil to tint a portion of your soap. However, you’ll likely get a very subtle color compared to mixing the same quantity of madder root powder. There are of course ways to used infused oils to color your swirls as the video just below explains.

Just be careful, because adding a lot of extra oil, or oil to some parts of the soap batch and not to others, could lead to seepage issues. If the oil is already calculated as part of the soap recipe or added as a small amount of extra oil it will work though. Annatto seeds for one – infuse annatto seeds into a carrier oil for a month or two, and less than a teaspoon of oil would be enough to tint a generous portion of a 28 oz (800 g) batch of soap yellow to orange.

How to Add Colorants

When swirling soap, you make a single batch of soap, bring it to the lightest trace possible. You then divide the soap batter into separate containers and color them individually. The way you pour them into a mold, and what you do with the soap after, is what creates the swirls.

I’ve already recommended using powdered versions of natural soap colorants, and in some cases, you can plop a teaspoon of it in and use a whisk or spatula to mix it in. Some colorants can create clumps, though, so it’s best to mix with a little water to make a paste first. Also, be aware that if you add a lot more water, oil, fragrance, or even clay to different parts of the batch, you could end up with weird and perhaps undesired results.

How much Colorant to Use When Swirling Soap

Silicone loaf molds are the most popular molds for creating swirled soap, and the smallest size I’ve seen is for a 1-lb (454 g) batch. I don’t use them myself but don’t see that they’d be an issue if you wanted to experiment. The loaf molds I have are for 28 oz (800 g) batches of soap. The weight measurement refers to the amount of oil/butters in a soap recipe by weight, not the full weight of a recipe. There are much larger soap molds to work with too, and homemade ones made of wood or cardboard lined with greaseproof paper work too.

For 28 oz (800 g) batches of soap, I tend to use a maximum of five teaspoons of powdered colorant. I first mix the powder in a small amount of water and add it bit by bit until I like the color. You can use a little more or less though, depending on the shade you’re trying to achieve. Keep in mind that too much color can cause a few issues though. That includes coming off the bar and tinting the lather and possibly your tub. That’s the case with turmeric. Some natural colorants, such as madder or spinach powder, may also have a slightly gritty texture if you use too much. Also, keep in mind that gelling soap (more info further below) can help intensify colors. You’ll never really know what the final color will be until you cut and cure a batch.

Slowing Down ‘Trace’ for Swirling Soap

In simple soap recipes, a quick time to trace isn’t usually a big issue. When your soap begins thickening up, you stir in your essential oil, pour into molds, and you’re finished. In making swirls, you want to slow that whole process down to have time to work.

That means you should avoid stick-blending too much, soap recipes that are water-discounted too heavily, and fragrances that accelerate trace. It’s best if you also aimed to mix the lye solution and oils between 85-95°F (29-35°C) and to skip recipes high in fats that trace quickly. Saturated fats like cocoa butter, palm oil, shea butter, castor oil, and coconut oil are all fats that speed up trace time. If it’s solid at room temperature, it’s likely to speed up trace.

Ensure that your recipe has its full amount of water (it’s not water-discounted) to give you the most amount of time to work. This amount is different for every recipe but easy to work out – multiply the amount of Sodium hydroxide in a recipe by three. The more water in a recipe, the more time it takes to thicken up, and this full amount is the maximum you should use.

The Best Soap Recipe for Swirling

You can swirl many soap recipes but one that doesn’t come to full trace quickly is going to be best. The slowest-moving soap recipe is probably pure olive oil soap, also called castile soap. If you make it with extra virgin olive oil (evoo), it’ll be at its slowest, and you’ll have plenty of time to work. However, the natural color of the soap will be greenish-yellow. That color can interfere with any additional colors you might want to add.

Pomace olive oil will be lighter in color, but it does trace a bit quicker than evoo. Still, Castile soap using pomace olive oil could be a great candidate for the best soap recipe for swirling. You can also use other recipes that are high in canola oil or sunflower oil—basically, soaps with high percentages (above 50%) of unsaturated fatty acids.

Making Naturally Colored Soap More Vibrant

Natural soap colorants tend to meld into one another, creating fuzzy boundaries rather than sharp lines. They also tend to be more earthy and subdued in tone too. There are two last recommendations that I have for you to ensure you get the most vibrant and defined swirls.

When you mix the color into your soap batter, it should be at a very thin trace. However, you want it to be medium-trace (the thickness of warm custard) when you begin pouring. Allowing the soap to thicken up a bit helps to create defined color borders.

To enhance natural soap color, you should also aim to gel your soap. The easiest way to do this is to oven-process it. Once you pour your soap into its mold, place it in an oven to gel. For large batches, it can be a cold oven, since the heat of the soap will be all that’s needed. For small batches, first, warm the oven to its lowest setting then turn it off.. Leave the soap inside overnight, if not a full day, before taking it out.

Swirling Soap with Natural Colors

All of the tips above will help you to make swirled soap using natural colorants of your choice. Experiment to your heart’s content, and have fun! When starting something new you’re bound to have successes and challenges so don’t worry about perfecting swirling in your first attempts. If you’d like to explore more ideas for making plant-based soap, check out these creative ideas:

• Ways to use plants in soap making
• How to Naturally Color Soap with Clay (earthy soap colorants)
• Comprehensive List of Natural Soap Colorants
• How to make soap without lye (your questions answered)