Technique · Layering
Straight-Line Layer Pour
The one technique that decides whether the rest of your soap looks deliberate: three bands, poured at the right trace, with a boundary you can read across the room.
RBase recipe to pour into
| Oil | Share | SAP |
|---|---|---|
| Olive Oil | 5 % | 0.134 |
| Coconut Oil (76 °F) | 2 % | 0.183 |
| Palm Oil | 2 % | 0.141 |
| Castor Oil | 5 % | 0.129 |
| Shea Butter | 5 % | 0.128 |
| Oil bill | 1 % | 137.4 |
| NaOH to weigh | 138.8 g | NaOH @ 99 % |
|---|---|---|
| Water to weigh | 330 g | 2.4 : 1 |
| Superfat | 5 % | Lye concentration 29.4 % |
| Yield | 9 × 163.2 g | Cure 5 weeks |
Reference bands follow the usual cold-process targets; the marker turns orange when a figure sits outside its band.
TTechnique notes
Everything is trace
A layer holds because the band below it has set enough to carry the weight, and it stays flat because the band above it is thin enough to level itself. Both of those are functions of trace and nothing else. Too thin and the bands merge into a blur; too thick and the upper band sits on top in a lump you cannot smooth out.
The working window is narrow but generous enough: from emulsion to medium trace on a 50 % olive bill is about twelve minutes at 22 °C. Start pouring as soon as the batter is at the point where a drip sinks into the surface within two seconds.
Pour rate, not pour technique
The bands drift in thickness along the loaf when the pour rate changes, not when the aim is off. A pour that starts fast, slows in the middle and speeds up at the end produces a band that is fat, thin, fat. Counting at a steady pace while you pour is a real technique, and it is why the pour looks calm in the video and frantic the first time you try it.
Pour down the side of the mould or over a spatula. Never into the middle, and never from a height — a 20 cm drop will punch straight through a skinned band.
Waiting four minutes
The wait between bands is the part people skip. In a 22 °C room with a 50 % olive bill, four minutes gives you a skin that holds a finger-touch without deforming. Two minutes and the new band sinks; eight minutes and the boundary tears as the fresh soap drags the set band sideways.
If your kitchen is 28 °C the wait drops to about two and a half minutes. If it is 18 °C it goes to six. Touch the surface rather than trusting the clock.
Add at trace
- 1 g titanium dioxide dispersed in 5 g oil for the middle band
- 1 g French green clay in 10 g water for the bottom band
Equipment
- Digital scale to 0.1 g
- Stick blender
- Three jugs — one per band
- A silicone spatula for floating the layers
When it goes wrong
- The second band sank into the first and you have a swirl instead of a line
- The first band had not skinned over. Four minutes at 22 °C; longer in a cold room, shorter in a warm one. Touch it with a clean finger — it should feel like set custard, not liquid.
- The layers bulge in the middle of the loaf
- You poured the middle band into the centre of the mould instead of against the spatula, so it punched down and displaced the band below. Always pour onto the spatula, always along the length.
- The white band has grey streaks
- Titanium dioxide that was not dispersed. TiO2 clumps in oil if you stir it; it needs to be worked against the side of a cup with a spatula until it is a smooth paste with no specks.
MMix
- Make the base batter exactly as the recipe card says, but blend only to emulsion. You need it pourable for another fifteen minutes and a batter at emulsion will get there on its own as you work.
- Split it into three jugs, 340 g each. The remaining 20 g is your working margin — expect to lose a little to the sides of the jugs.
- Dye the bottom jug with the clay slip and whisk it in. Dye the middle jug with the titanium dioxide. Leave the top jug plain.
- Check all three: a drip from the spatula should sink into the surface and disappear within two seconds. That is thin enough to level itself and thick enough to hold a layer.
- Pour the bottom band down the side of the mould, not into the middle. Counting to a steady rhythm as you pour is not superstition — an even pour rate is what stops the band from drifting in thickness along the loaf.
- Wait four minutes. Not three, not ten: the first band needs to skin over enough that the second one does not punch through it.
- Pour the middle band over the back of the spatula, holding the spatula two centimetres above the first band and moving it along as the level rises.
- Repeat for the top band after another four minutes, then tap the mould down and insulate for 24 hours.
CCut
- Unmould at 24–36 hours, while the loaf is still slightly soft. A very hard loaf chips at the layer boundaries when you cut it.
- Cut at day 3 with a flat blade and a single, slow, downward stroke. Do not saw. A sawing motion drags colour across the boundary and the whole point of this technique is a boundary you can read.
- Nine bars at about 118 g. The bands should be within a couple of millimetres of even along the whole loaf; if they drift, your pour rate was uneven, not your trace.
CCure
- Five weeks. Layered bars cure exactly like unlayered ones — the layers are one soap by the time they are cured, and they will not separate in use.
- One caveat worth knowing: the titanium dioxide band is slightly harder than the other two, because TiO2 is a particulate filler. On a wet bar you can feel the middle band as a faint ridge after a few weeks of use. It is cosmetic and it is the price of a clean white.
What matters here
- Pour at the point where a drip sinks into the surface in about two seconds. Thinner merges, thicker lumps.
- Pour against the side of the mould or over a spatula, never into the centre.
- Four minutes between bands at 22 °C — test with a finger, not the clock.
- Cut with one slow downward stroke at day three. Sawing drags colour across the boundary.
- Layers do not separate in use; they are one soap once cured.
Questions that come up
- Can I layer with a fragrance in the batter?
- Only if you know it does not accelerate. Many floral and spice oils will take a thin batter to medium trace in under a minute, and a layered pour has no margin for that. Make the plain version first.
- How do I get more than three bands?
- Use less batter per band and accept thinner lines, or pour into a taller, narrower mould. Five bands in a standard 1.1 kg loaf gives you lines about 1.2 cm thick, which reads as stripes rather than layers.
- Why did my layers come out wavy?
- Because each pour was not level before the next one went on. Tap the mould once on the bench after every band, not just at the end.
Next on the bench
Cold-process soap is made with sodium hydroxide: goggles, gloves and ventilation, and keep the batch away from children and animals. A straight line is a pouring skill, not a property of the soap — the bar cleans the same whichever way the layers run.