In this article, I will explain the process of making soap with milk and give tips to help you avoid the most common mistakes. Making soap with milk can be fiddley, but the results are worth it. Once you have tried it, it will seem less complicated.

Milk contains fats and proteins, which act as natural emulsifiers. This means you can get a lovely creamy bar of soap that is not as harsh on the skin.

Why is making soap with milk different from a standard Cold Process (CP) soap recipe?

You need to be careful when adding Lye to Milk because Milk has natural sugars; if you heat it, you can caramelise or burn it. So, if you didn't take some simple extra steps, you might end up with yellow or brown spots or colour the whole soap a dark brown instead of a nice creamy white bar of breast milk soap. If this happens to you, you will know about it because it will continue to smell bad after a week.

When making soap with water, you must use a high percentage of lye water to create a reaction that results in saponification. Saponification describes the chemical reaction of lye water mixed with Fats, Oils, and Butters.

Lye is hot! Pouring your lye crystals into the water shoots up to over 80C (170F). If you look online, you will find enough photos of injured soap makers who did not take the proper precautions. So always wear the right clothes, keep your skin, eyes and mouth covered, and don't spill anything. If you are clumsy (like I am), ensure you don't walk around with the solution once you have mixed it. I do this in my workshop and open every door and window possible.

Many people add lye crystals directly to frozen milk blocks, which works well. You have to experiment and find what works best for you. I outline the different methods below; they all have positives and negatives.

Why is milk an excellent replacement for water in soap?

Raw milk contains antioxidants, vitamins A, D, B6, and B12, including biotin, calcium, protein, fats, and sugars. Saponification can alter the number of nutrients in your soap, but some remain.

The main reason people use milk in soap is that it lowers the pH level of your soap, which means it is gentler on the skin. So, people who find soap typically too harsh and dry (because of the higher pH) will be likelier to enjoy a milk soap.

The lactic acids in your milk soap also make the whole feeling on your skin more luxurious and moisturising.

What kinds of milk can I use to make soap?

Any milk!

• Human Breast Milk
• Goats Milk
• Horse Milk
• Cow Milk
• Donkey Milk
• Sheep's Milk
• Coconut Milk (okay, it isn't mammal milk, but it's still a thing)

It is worth noting that they all have different fat and sugar levels. For example, goat's Milk will add extra fat to your recipe, and Human Breast Milk has much less protein than Cow Milk and much more sugar. So, depending on the milk, you might have to experiment a little.

Assume you're using SoapCalc and do not add milk to the recipe (unless it is cow's milk, as that option exists). The simplest way to use the soap calculator when making milk soap is to keep the superfat content at no more than 5%.

Can I use sweetened condensed Milk instead of regular Milk?

No, you cannot use sweetened condensed milk to replace milk or water. It has 30 times more sugar than regular milk, making it more likely to burn. But having said that, it doesn't mean you can't add it.

It would be better to treat it like honey and stir it when your mixture is almost at trace, perhaps at the same time as any fragrance or other additive.

How do I add Lye to Milk without burning it?

The five popular methods outlined below are available. It is about finding the one that works for you. The whole point of being careful when adding the lye crystals is to ensure you don't burn the milk, which smells horrible if you do. Making milk soap doesn't smell great for about a week after you have cut it; that is normal.

If you burn it, it will always smell bad, and all your excitement for your beautiful new soap will have to go into the bin. But never fear! If you have made soap before, you can do this too. You have to take care and take it slow.

Adding Milk & Lye: Method 1

Combine the water and milk without the lye crystals in a large container. Place the container in the freezer for 1 to 2 hours. It should get slushy, but don't let it freeze solid.

Then with safety gear on in a well-ventilated place, add 1/4 of the crystals to the cold milk water, and stir slowly. Wait 20 minutes and add another 1/4, and so on.

Take your time. Don't rush. We are trying not to burn the milk.

Adding Milk & Lye: Method 2

This is the 3:1 ratio. For example, perhaps your recipe calls for 400g of lye water, but you will replace 1/4 of that with your chosen milk, so 100g.

Mix the lye crystals (for your 400g water requirement) with 300 grams of water and add this to the oils. Once the soap reaches a thin trace, add the milk and continue blending until a medium trace is achieved. Finally, add the remaining ingredients. Coming to Trace might happen faster than expected, so be prepared.

Some recipes suggest 50/50, but a point to note is that the less water you have in your recipe, the faster it comes to trace, and if you are starting, it might be a little stressful! The recipe below has honey, which can also accelerate your trace.

Adding Milk & Lye: Method 3

Pour your milk (as a total replacement of the required water) into an ice cube tray. Once the milk has completely frozen, take it out and put it into your Lye mixing container. Slowly, very slowly, add some of the crystals and stir continuously. Keep adding some more crystals until completely dissolved, and you will notice there is no more ice, and the milk is once again a liquid.

The temperature will rise as the lye flakes dissolve into the milk, so keep your eye on it. Another way to keep the temperature low is to put the container in another cold water tray, like an ice bath, as you stir.

Make sure that the Lye dissolves completely, and you will know that this happens when the temperature stops rising, so keep an eye on your temperature. Either with a thermometer or a temperature gun. As mentioned, if the milk gets too hot, it will discolour, and you will end up with smelly brown mush.

As an extra precaution, you can put your Lye milk solution through a sieve and pour it into the oil mixture to ensure everything dissolves.

Adding Milk to Lye: Method 4

Using the 3:1 water-to-milk ratio (Method 2), mix your water and milk and then pour them into ice cube trays and freeze them overnight. Then, slowly add your Lye crystals (Method 3).

The benefit of higher water content so it will be slower to come to trace,

Adding Milk to Lye: Method 5

Method 5 is possibly the easiest of all and closely resembles Method 2. After mixing your lye water and oils and reaching a light trace, ensure the temperature is low. Add 1 or 2 ounces of milk and other additives, clay or essential oil.

It probably won't have the same creamy result, but it will still be a milk soap!

Gel Phase

Typically, with Cold Process soap, you would insulate it overnight in a box, blanket, or warm oven. But because of the milk, you might consider putting it in the refrigerator instead and ensuring that rising temperatures don't scorch it. If you live in a hot environment, perhaps you want to put it in the freezer.

Putting your CP soap in the refrigerator or freezer prevents the Gel Phase. Some people love it. Some don't.

Smell Warning: because of the milk, it will not smell very nice for the first seven days. If it continues to smell after this date, you might have scorched your milk, and you can't use it as it won't ever smell lovely. However, I have made beautiful milk soap without any smell whatsoever.

PET TEST

After a few days, do a PET test. These little strips of paper will test the pH level of your soap. The easiest way to do this is to pick an end piece of soap you don't mind messing up and wet it a little. Then, dip your PET strip of paper into it. You want to aim for between a 7-10 result. Anything above ten would be too harsh on the skin, with too much Lye, and you can't use it.

Some people do a “zap test,” where they use their tongue on the soap, and if it is zappy, like a zing off a battery, then it's too Lye heavy. I did this once, but don't do it. It isn't enjoyable to have soap in your mouth! The paper is more accurate, and you don't have to wash your mouth with soap, haha!

I hope you enjoy making soap with milk.

Soap-making with milk is rewarding because it feels luxurious on the skin. It can also be moisturising and suitable for sensitive skin. It's also a great way to add nutrients, vitamins, and minerals to the finished product. For new moms, this method is also excellent for using excess breast milk, especially if you spend a lot of energy expressing it.

Enjoy, and please let me know if you have any questions or how your recipe worked in the comments below. Remember, always use a lye calculator and wear safety gear.