What a swirl is
A swirl is a pattern made by combining two or more colors of soap batter and moving them around before the soap sets. The finished bar shows the marbled design when it is cut or unmolded. Swirls are usually made with cold process soap, because the batter stays fluid for a while and gives time to work.
Nearly every swirl technique comes down to the same three things: how thick the batter is, how many colors you use, and how much you move the batter. Thin batter flows freely and blends easily. Thick batter holds its shape and gives sharper lines. Moving it too much turns the colors muddy.
Before you start: planning
Swirling asks for more planning than plain soap.
- Choose a slow recipe. A recipe that stays fluid longer gives more time to work. Some scents speed up batter, and a rushed batter can seize, a problem described in the article on soap seizing.
- Measure and color ahead of time. Split the batter into portions, color each one, and have tools ready before you pour.
- Pick colors with contrast. Colors that are close together blend into a soft look. Colors that are distant, such as white and a deep brown, show the pattern strongly.
- Test your pigments. Some natural colors shift or fade, and some bleed into neighboring colors. Our guide to natural soap colorants goes through those effects.
- Consider temperature and gel phase. Gel phase can deepen colors and sometimes alter how a swirl looks. See the article on gel phase.
Swirls made in the pot
In-the-pot swirl. Pour two or more colors into the main pot together, in streaks or blobs, then give it a few gentle stirs with a spatula, a spoon or a stick before pouring into the mold. Less stirring gives bolder streaks, and more gives blended marbling. It is one of the simpler techniques and a good first try, because the mixing happens before you pour.
Drop swirl. Colors are poured into the mold from a height, in alternating spots, so they sit in blobs and slightly blend into each other. After pouring, a skewer or a spoon pulled through the surface can create a pattern. Because the colors are added in pieces, a drop swirl needs batter at a medium thickness.
Swirls made in the mold
Hanger swirl. After pouring colors into the mold in layers or bands, a wire hanger (often reshaped into a kind of tool) is pulled through the batter in a pattern, usually back and forth, lifting colors from the bottom up. The result is a wave-like or feathery design visible when the loaf is cut.
Skewer or chopstick swirl. A thin tool is drawn through the batter in loops, zigzags or figure eights. It is useful for decorative tops. The pattern on a top swirl is often only on the top and does not run through the bar.
Spoon swirl or textured top. The batter is dabbed with a spoon to form peaks and ripples. This is more a finish than a swirl, and the pattern is on the surface only.
Funnel or “Taiwan” pour. Batter in two colors goes into a vessel that pours both at once, or colors are poured through a funnel into the mold. The outcome looks like concentric rings or soft flowers. It needs practice and is better attempted after a few simpler batches.
Dividers and column swirls. Pouring colors into separate sections of the mold, divided by a removable divider, then lifting the divider and giving the batter a gentle swirl, is an approach used for defined, mirrored patterns. Layering ideas of this kind overlap with the article on soap layers.
When in the batch to swirl
Timing differs by technique.
| Style | Typical point |
|---|---|
| In-the-pot | While the batter is thin to light trace, before pouring |
| Drop swirl | Light to medium trace, after the colors are poured |
| Hanger or skewer | After colors are in the mold, with the batter at medium trace |
| Textured top | At the end, with thicker batter |
The point where the batter holds a visible trail is called trace. Light trace is thin, like thin pudding, while medium trace is thicker. Your recipe, your oils and your fragrance all affect how fast you reach each stage, so the timing is a guide and not a rule.
Common problems
- Muddy colors. Too much stirring or colors that mix badly. Stir less, and avoid pairing colors that make a dull brown when blended.
- Lines that vanish. Batter that is too thin. Wait a bit longer next time.
- Thick, lumpy batter that will not swirl. A fast-moving recipe or fragrance. Plan with a slower recipe and have the colors ready.
- Soda ash on top. A powdery film that may spoil the look of a textured top. See soda ash.
Practice and safety
Swirls take practice, and your first few attempts are rarely exactly what you imagined. Keep notes. Cutting reveals the design, so see the article on cutting soap for tips on clean edges. Throughout, treat lye with care: use protective gear, ventilate the space, keep children and pets away, and follow a trusted tested recipe.