Formula · With additives
Goat Milk, Honey and Oatmeal Bar
Milk soap, done cold: the milk is frozen into a block so the lye cannot scorch it, and the loaf goes into the fridge to stop the sugars caramelising. Get those two things right and this is one of the best bars you will ever make.
RRecipe card
| Oil | Share | SAP |
|---|---|---|
| Olive Oil | 35 % | 0.134 |
| Coconut Oil (76 °F) | 25 % | 0.183 |
| Palm Oil | 2 % | 0.141 |
| Shea Butter | 1 % | 0.128 |
| Castor Oil | 5 % | 0.129 |
| Avocado Oil | 5 % | 0.133 |
| Oil bill | 1 % | 137.9 |
| NaOH to weigh | 139.3 g | NaOH @ 99 % |
|---|---|---|
| Water to weigh | 300 g | 2.18 : 1 |
| Superfat | 6 % | Lye concentration 31.5 % |
| Yield | 9 × 159.9 g | Cure 6 weeks |
Reference bands follow the usual cold-process targets; the marker turns orange when a figure sits outside its band.
TTechnique notes
Why the milk has to be frozen
Dissolving 138 g of sodium hydroxide in water releases enough heat to take the solution past 80 °C. Milk proteins denature around 70 °C and milk sugars caramelise from about 60 °C. Pour lye onto liquid milk and you get an orange, scorched, curdled mess in under a minute.
Frozen milk in a flat block melts at exactly the rate the lye dissolves it, which holds the jug near 25–30 °C with no effort. The ice bath is there for when you get impatient and stir too fast.
What the honey and oatmeal actually do
Honey is a humectant: it holds water, which makes the finished bar feel smoother on wet skin and makes it go soft faster in a wet shower. It also adds sugar, and sugar heats the reaction. At 20 g on a 1000 g bill it does the first thing without doing much of the second.
Colloidal oatmeal is finely ground oats that stay suspended rather than sinking. At 25 g it gives a light scrub and a faint creamy colour. More than 40 g and you are making a kitchen scrub, not a bath bar.
The profile
Hardness 41, cleansing 17, bubbly 21, conditioning 55, creamy 24, INS 151. Every marker is comfortably inside its band and nothing is pushed. The 6 % superfat is high for a bar with 25 % coconut, and that is deliberate: milk soaps feel drier than the numbers suggest because the proteins bind some of the free oil.
Add at trace
- 150 g frozen goat milk, replacing 150 g of the water
- 20 g raw honey, stirred into the oils before the lye
- 25 g colloidal oatmeal, added at trace
Equipment
- Digital scale to 0.1 g
- Stick blender
- An ice bath and a jug that can take a lye solution at 30 °C
- Fine mesh strainer for the oatmeal
When it goes wrong
- The lye jug went orange and smelled of burnt sugar
- The milk got above 40 °C. It is scorched and there is no fixing it — the bar will be orange all the way through. Freeze the milk into a flat block next time and keep the ice bath under the jug.
- The bars are covered in an orange-brown crust
- Gel. Milk soap generates enough heat on its own to reach gel and the sugars caramelise at the edges. Refrigerate the mould for the first 12 hours.
- The loaf cracked down the middle
- Too much honey, more than about 3 % of the oil weight, plus insulation. Honey is a sugar and it feeds the reaction. 20 g on a 1000 g bill is the ceiling.
MMix
- The night before: freeze 150 g of goat milk into a single flat block about 2 cm thick. A block melts slowly, and slow melting is the whole trick — cubes melt fast and the milk scorches.
- Set the jug in an ice bath. Weigh the frozen milk block into it, then weigh 138.2 g NaOH on top. Stir with a spatula, not the blender, pressing the block down into the lye as it melts. Keep the mixture under 30 °C at all times. If it climbs, stop stirring and let the ice bath catch up.
- When it is a smooth, tan, cool liquid with no lumps, add 120 g of distilled water to bring the total liquid to 270 g — that is your 30 % water ratio, milk included.
- Melt the oils to 45 °C and stir the 20 g honey into them. Honey in the oil phase, never in the lye: honey plus concentrated lye is an exothermic volcano.
- Cool both to 32 °C. Milk soap wants a lower working temperature than a plain water batch, because the sugars and proteins will scorch and the whole loaf will go orange if it gets hot.
- Blend to medium trace, then fold in 25 g of colloidal oatmeal with a spatula. Pour immediately and put the mould straight into the fridge for 12 hours — milk and honey both run hot and gelling turns this loaf orange-brown.
CCut
- Leave it in the fridge for 24 hours, then move it to a cool room. Do not insulate, do not wrap.
- Unmould at 72 hours. A milk bar is softer than a water bar at the same age and it will be slightly tacky on the outside. If it sticks, another day in the cold will fix it.
- Cut at day 6. Nine bars at about 118 g. Wipe the blade between cuts — the honey makes the cut face drag.
CCure
- Six weeks in a cool, dry, ventilated room. Milk is 87 % water and this loaf holds more of it than a water batch, so the first three weeks are mostly drying.
- Do not cure milk soap in a warm room. Above 27 °C the residual milk sugars continue to brown and the bars darken by several shades over the six weeks. That colour is cosmetic and the soap is fine, but it costs you the pale tan.
- The honey keeps drawing moisture from the air for months. Keep the bars wrapped once they are done, or they will go soft again in a humid bathroom.
What matters here
- Freeze the milk into a flat block and keep the lye jug under 30 °C. That is the whole technique.
- Honey goes into the oils, never into the lye. 20 g per kg is the useful ceiling.
- Refrigerate the mould for 12 hours to stop the sugars browning the loaf.
- Unmould at 72 hours, not 24 — milk bars are soft at the same age.
- Hardness 41, bubbly 21, conditioning 55, 6 % superfat.
Questions that come up
- Can I use cow's milk or coconut milk instead?
- Yes to both, same method. Coconut milk has less protein and more fat, so it browns less and the bar is slightly softer. Powdered milk reconstituted at double strength works too and is far easier to keep on hand.
- Do I have to use colloidal oatmeal?
- No, but do not substitute rolled oats straight from the packet — they are too coarse and they will go mouldy in the bar. If you only have rolled oats, blitz them in a blender until they are flour with a bit of grit left.
- Why is my bar darker than the photograph?
- Warm curing. Milk soap cures pale in a room under 22 °C and browns above 27 °C. It is the same soap either way.
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. Milk and honey are foods, not medicines; this bar cleans skin, it does not treat any condition.