Homemade Goat Milk Soap Recipe for Beginners: Cold Process

This homemade goat milk soap is a small-batch, cold-process bar made with olive oil, coconut oil, shea butter, castor oil, sodium hydroxide (lye), and frozen goat milk. The measured formula and step-by-step method keep the process manageable for beginners, while a slow cure helps the finished bars become firm and long-lasting.

Ingredients

8.8 oz (250 g) olive oil
4.4 oz (125 g) coconut oil, preferably 76-degree coconut oil
2.65 oz (75 g) shea butter
1.75 oz (50 g) castor oil
2.4 oz (69 g) 100% sodium hydroxide lye, also called NaOH
5.65 oz (160 g) goat milk, frozen into cubes or a thick slush

Use a digital scale that reads in grams for every ingredient, especially the lye. The ounce amounts are weight, not fluid ounces; do not replace these measurements with cups or spoons because small measuring errors can make a lye recipe unsafe or leave the soap too harsh. This lye amount is calculated for these exact oils at about 5% superfat. Use pure sodium hydroxide intended for soap making, not drain cleaner with added ingredients.

Instructions

Set up safely. Choose a well-ventilated work area away from children, pets, food, and distractions. Put on splash goggles, chemical-resistant gloves, long sleeves, and closed shoes before opening the lye. Use a digital scale, stainless-steel or lye-safe heat-resistant plastic containers, a silicone spatula, an immersion blender, and a silicone loaf mold sized for a small batch. Never use aluminum: lye reacts with it. Keep all soap-making equipment separate from equipment used for food.
Weigh and prepare the ingredients. Weigh each oil, butter, milk, and lye separately; do not estimate. If the goat milk is not already frozen, freeze it in cubes ahead of time. Set the milk container in a larger bowl of ice so it stays very cold while you work. Line a mold only if its material requires lining, and make sure it is stable and ready before mixing.
Melt the solid fats. Melt the coconut oil and shea butter gently in a stainless-steel pot over low heat, or in short bursts in a microwave-safe lye-free container. Remove from the heat as soon as they are liquid. Stir in the olive oil and castor oil. Let the blend cool until it is warm but not hot, roughly 90–100°F (32–38°C). Do not rush the cooling with a refrigerator, which can cause fats to solidify unevenly.
Mix the lye into the frozen milk. Place the frozen goat milk in a heat-resistant container set in an ice bath. Slowly sprinkle the weighed lye over the milk a little at a time, stirring gently after each addition until it dissolves. Always add lye to the liquid, never pour liquid onto a pile of lye. The mixture heats as the lye dissolves; adding it gradually and keeping it cold helps limit scorching and the strong odor that can develop if milk overheats. Avoid breathing directly over the container. Let the mixture cool to about 90–100°F (32–38°C), keeping it out of reach while it cools.
Bring the oils and lye mixture together. When both mixtures are in a similar temperature range, pour the lye-and-milk mixture through a fine non-aluminum strainer into the oils if any undissolved milk solids are visible. Put the immersion blender head fully under the surface before switching it on, so you do not splash. Pulse for a few seconds, then stir by hand; repeat until the mixture reaches light trace. Light trace means it is slightly thickened and a drizzle briefly leaves a faint line on the surface. This often takes a few minutes, but the exact time varies with temperature and blender strength.
Pour into the mold. As soon as the batter reaches light trace, pour it into the prepared mold and gently tap the mold on the counter to release large air pockets. Scrape the container with a dedicated spatula, but do not splash batter. Smooth the top if you like. Do not insulate this milk soap heavily: excess heat can darken the batter or cause a crack. Leave the mold in a cool, undisturbed place, away from children and pets.
Unmold and cut. After 24–48 hours, check whether the loaf is firm enough to release cleanly. If it bends or sticks, wait another 12–24 hours rather than forcing it. Wearing gloves, remove the loaf and cut it into about six bars with a soap cutter or a straight, non-serrated knife. Freshly unmolded soap may still be caustic, so handle it with gloves and avoid skin contact.
Cure the bars. Arrange the bars with space between them on a rack in a cool, dry, well-ventilated place, out of direct sunlight. Cure for six weeks, turning them occasionally so air reaches all sides. Cold-process soap firms as water evaporates and the bar develops a milder, longer-lasting feel. Do not use the bars early just because they are hard to the touch; the full cure is part of the recipe.

Tips

Do not change the oils or lye amount casually. Each oil needs a different amount of sodium hydroxide. If you substitute or change a quantity, recalculate the complete formula with a reputable soap lye calculator and confirm the superfat setting before making it. Never guess at a lye adjustment.
Keep the milk cold and add lye slowly. Goat milk can discolor or develop a scorched smell if the lye mixture gets too hot. Frozen cubes, an ice bath, and small additions help control temperature. A tan or caramel shade can happen even when the soap is otherwise made correctly.
Use gloves for fresh soap. Uncured batter and newly cut bars can irritate or burn skin. If lye solution or raw soap batter contacts skin, rinse the area under plenty of cool running water; for eye exposure, flush continuously with water and seek urgent medical advice. Do not try to neutralize lye on skin with vinegar.
Keep the formula fragrance-free for a first batch. Fragrance and essential oils can speed thickening or behave unpredictably, and they need their own suitable usage rates. Once comfortable with the base recipe, use only a skin-safe soap fragrance at its supplier’s recommended rate and recalculate the batch if needed.

Serving Suggestions

These are bath or hand-washing bars, not food. Once the six-week cure is complete, wet your hands or a washcloth, work up a lather, and rinse thoroughly. A soap dish that drains between uses helps the bar dry instead of sitting in a puddle. For a new bar, try it on a small area first; stop using it if it causes irritation, and keep it out of eyes and away from children who might mistake it for something edible.

Variations

Try a different milk: You can use frozen cow’s milk in place of goat milk at the same weight for a similar creamy, milk-based bar. The finished color and scent may differ slightly. Any milk substitution should still be weighed, kept cold, and paired with the same lye amount only when the oils and their weights remain exactly as listed.

Add a simple scent: A soap-safe fragrance oil can add scent, but not every fragrance is suitable for cold process, and some can make batter thicken rapidly. Check the product’s documentation for cold-process use and maximum usage rate, then weigh it rather than measuring by eye. For a first batch, leaving the soap unscented makes it easier to recognize normal changes in trace and color.

Change the color carefully: For colored bars, choose a colorant specifically labeled for soap and follow its supplier’s dispersion instructions. Avoid food coloring, which may not behave as expected in soap, and avoid adding water-based ingredients by guesswork. Keep any decoration modest so the small batch remains easy to pour and cut.

Make a larger or smaller batch: Scale every oil and the liquid in the same proportion, then recalculate the lye for the new total and chosen superfat with a lye calculator. Do not simply multiply a rounded lye figure if the oil blend changes. A scale accurate to at least 1 g is important; a more precise scale is helpful for smaller batches.

Storage and Reheating

There is no reheating step for cold-process soap. Let the bars cure for six weeks before use, then store unused bars in a cool, dry place with airflow, away from direct sun, humidity, and strong odors. A paper box or breathable wrap works better than sealed plastic for long-term storage because trapped moisture can soften the bars. Properly cured bars commonly keep for about a year or longer, though scent and color can fade over time; discard a bar if it develops an unusual rancid odor or visible contamination. Between uses, keep each bar on a draining dish and allow it to dry.

Frequently Asked Questions

Can I use fresh goat milk instead of frozen milk?

Yes, but freezing it first is a helpful temperature-control step for beginners. Fresh milk warms quickly when lye is added, which can encourage scorching and discoloration. Weigh the milk before freezing, then use the same 160 g (5.65 oz) amount. Do not add extra milk to compensate for melting or evaporation.

Can I replace sodium hydroxide with baking soda or liquid soap?

No. Sodium hydroxide is the alkali used to turn these oils into solid soap, and baking soda or liquid soap will not perform the same job in this formula. Potassium hydroxide is used for different soap formulations and requires a separately calculated recipe. Do not substitute one alkali for another by weight.

Why did my goat milk soap turn tan or smell different?

Milk sugars and proteins can darken when exposed to the heat produced as lye dissolves and soap sets. A cream, tan, or light caramel color can be normal. Keeping the milk frozen, adding lye slowly, and avoiding heavy insulation can reduce overheating, but they cannot guarantee a perfectly white bar. A strong burnt odor may indicate that the milk mixture overheated.

How do I know the lye has been measured correctly?

Use a calibrated digital scale, weigh the exact oils listed, and check that the lye is pure sodium hydroxide. The 69 g amount is based on this specific formula and about a 5% superfat. If any oil, oil quantity, or lye purity changes, verify the whole recipe in a lye calculator before proceeding. Do not rely on pH strips or a touch test to correct a mismeasured batch.

Can I use the soap after it has hardened in the mold?

Wait for the complete six-week cure. Being firm enough to unmold only means the loaf can be handled and cut; it does not mean the bars have finished drying. The cure also helps the bars last longer in use. If the soap is still soft after the cure, give it additional time in a dry, airy spot.

What should I do if the batter gets thick before I pour it?

Work calmly and pour as soon as it reaches a manageable trace. If it thickens suddenly, do not add water or extra oil; gently spoon it into the mold and tap the mold to settle the batter. A rough top is cosmetic. For the next batch, check that fragrance or additives are not accelerating trace, and avoid blending longer than needed.

More recipes to cook

Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

Spotted an error? Tell us and we will correct it (corrections policy).