Yogurt Soap Recipe

Yogurt Soap Recipe

Breaking news: I have discovered my new favourite homemade soap recipe. Yogurt Soap.

I have been making soap for a couple of years now. If you've visited my blog before you will have seen my easy soap Recipe for Olive Oil Soap with Shea Butter. That is the soap recipe I started with and return to often. It is the one that helped me realise soap making was so much easier (and quicker) than I thought it was going to be. Provided you follow some safety rules of course.

In that post I referred back to a blog post about the basic equipment needed for soap making at home so please read that post if you haven't already. I would also advise you that, if you haven't made soap before, start with the Olive Oil and Shea Butter soap before making this recipe - reasons to follow.

How to Make Soap

The principles of making soap at home are the same for pretty much any cold pressed soap recipe. You melt the oils. You add lye to water and allow it to cool (the chemical reaction creates heat, volatility and the mix gives off fumes, hence safety issues). When the oils and the lye water drop to a similar low temperature, you combine them and put the liquid soap in a mould. When it's set you turn the soap out of the mould and leave it to somewhere to cure.

The Benefits of Milk in Soap

Cleopatra was known for taking milk baths for a reason. Milk is known for being gentle on the skin. People who suffer from skin conditions such as eczema find that milk soaps are easier on their dry and itchy skin.

Milk and variations of milk (such as yogurt) can make a beautiful creamy white soap which is a pleasure to look at as well as to use.

Why can't I start by Making Yogurt Soap?

Making soap with milk adds a tricky element to the soap making process. I mentioned that when you add lye to water, it creates heat. Milk contains natural proteins and sugars which scorch when they reach high temperatures. You may have had the experience of heating milk too quickly in a pan, and you get brown scorched milk and a particular smell, which can be unpleasant if you scorch the milk a lot.

The same things happens when you add lye to milk. Your milk (or, in this case, yogurt) will turn from creamy white to brown as the sugars scorch. It can also become volatile and overflow, which is absolutely not what you want with a product like lye. As if all that wasn't bad enough, the smell of the scorched milk can give your soap an unpleasant, ammonia-like smell.

The easiest way avoid your soap going brown, smelling weird or overflowing unsafely is to add in a stage where you manage the temperature of the liquids. Hence it is advisable to get a few bars of non-dairy soap under your belt before moving on to the slightly trickier recipes.

Reducing the Heat when Making Milk Soaps

The easiest way to deal with the heat produced when Lye mixes with Milk is to freeze the dairy product before mixing it with the lye. In the case of yogurt soap, I do this by mixing the yogurt with water and freezing it in ice cube trays before adding it to the lye.

What about Making Soap Without Lye?

You will have seen people online talking about making soap without lye. Well you can, and you can't. Soap is an alkali mixed with fats, which combine through the saponification process. Without lye, the fats won't combine. Once saponification has finished and your soap is fully cured, no sodium hydroxide remains in it. Your soap is, in effect, the neutral by-product of mixing acid and alkali.

The only way you can make soap without lye is if someone else has already handled the lye for you, ie by using a melt and pour soap base. If you want to make soap but you don't want to handle the lye, then melt and pour is the way to go. However this recipe assumes you are not using a base, but rather creating the soap from scratch. 

As always, don't be tempted to fiddle with this recipe in any way, or any soap recipe you find for soap. Creating new soap recipes is a tricky business unless you use a soap calculator to ensure you're adding the right quantities of everything so it works. I'll cover that another time. But for now just take my word for it. Don't fiddle with a tried and tested recipe because it won't work.

Yogurt Soap Recipe

Ingredients for Yogurt Soap

1. Olive Oil. You can use Organic Olive Oil produced specifically for making bodycare products, or a simple bottle of olive oil from the supermarket. Olive oil makes a soap with good cleansing properties, with very few bubbles in the lather.

2. Coconut Oil. Again you can use Coconut Oil made for use in beauty products, or the coconut oil in jars you find in the supermarket aisle. Coconut oil adds a fluffy lather to the soap.

3. Full fat, plain, natural yogurt. I make my own simple yogurt with UHT milk for making soap. When I know I'm going to make soap, I make a batch of yogurt and don't bother putting one of the jars in the fridge. Instead, as soon as it's cool, I just mix it with the water and put it in ice trays.

4. Sodium Hydroxide, aka caustic soda, aka lye. I've done the 'caution' bit to pieces I think so I won't bang on about it. But please treat this stuff with respect. Keep animals and children well away when you're working with it.

5. Water. I like to use distilled water to avoid any risk of contaminants getting into the soap mix and affecting the end result. But if I don't have any distilled, I use rainwater from the water butt. And if all else fails: tap water.

6. (optional) Essential oil(s) of your choice.

I covered the equipment you need to make soap in this post. 

Yogurt Soap - Step by Step Method

  1. Mix the yogurt with the water and freeze in ice cube trays.
  2. Make room in your freezer and fridge to accommodate your soap mould later.
  3. Weigh out the coconut oil.
  4. Put the coconut oil into the stainless steel bowl, put water in your saucepan. Pop the bowl of oils on top of the pan of water and heat the water gently. As soon as the coconut oil in the bowl has melted, remove the bowl from the heat and put it to one side to cool.
  5. Add the cold olive oil to the hot coconut oil.
  6. As the fats are cooling, put the yogurt and water ice cubes in a non corrosive jug (I use glass). Ensuring your sleeves cover all the skin on your arms, put on your rubber gloves and goggles. Weigh out the lye into another non corrosive jug.
  7. I always, without fail, do the next step outside out of the way of everyone. It also keeps the unpleasant fumes outside and, if you spill anything, your counter top isn't trashed. If you don't have easy access outside then you may choose to do this in the kitchen. Wherever you do it, please be careful. Add the contents of the lye jug to the water jug, NEVER THE OTHER WAY AROUND. This avoids the lye 'erupting' as the water (or, in this case, ice cubes) hit it. "Add water to lye and you may die" is a bit of an extreme way to think about it, but you get the idea.
  8. Stir the lye into the ice cubes slowly and gently with a spatula, and the ice cubes will quickly dissolve as the chemical reaction takes place. Ensure the lye dissolves fully in the yogurty water. 
  9. Once the lye has dissolved and cubes are fully melted, leave the jug of lye solution outside to cool.
  10. Wait until both the oils in the bowl and the lye solution have cooled to a temperature between 90 and 110 degrees F (32-43 degrees C). They don't have to be the same temperature, but they do both need to be within that range.
  11. Once the oils and lye solution have both cooled to within the temperature range, put on your goggles and gloves again. Bring the lye solution indoors and pour it into the bowl of oils, stirring gently with a spatula to start mixing. Make a note of the temperature at this point.
  12. Plug in the hand blender and submerge it below the liquid's surface so it doesn't splash. Turn on the blender and blend the mixture until it starts to thicken. This can be anything from 30 seconds to a couple of minutes, depending on the recipe. You are aiming to reach the point of 'trace', where your soap mixture leaves a trail on the surface when you drizzle it over. Another way to know you've reached trace is if the temperature of your soap has increased a few degrees from when you took the temperature in step 9. Don't be tempted to overblend. If you do, your soap will thicken too much and you won't be able to pour into into the mould.
  13. Add a teaspoon or so of your essential oil if using, and mix with the spatula until combined.
  14. Pour the soap into the mould, tap on a hard surface gently to level off or smooth it with the spatula. Unlike other recipes, do not cover or wrap the mould to create heat - heat is what we're trying to avoid.
  15. With gloves and goggles still on, put your mould uncovered into the freezer and leave for 30 minutes. 
  16. With your goggles and gloves on, immediately wash up everything else you've used as it's easier to do it now than when the soap has solidified later. I usually wash everything twice.
  17. After the mould has been in the freezer for 30 minutes, move it into the fridge. Leave the mould unwrapped and undisturbed for about 24 hours. 
  18. After 24 hours, remove the mould from the fridge. Wearing gloves again just in case the soap is still a bit acidic, turn out your soap onto a board. Cut it into slabs.
  19. Leave the bars of soap to dry and 'cure' for at least a month.


  • 595 g Olive Oil (any olive oil is fine)
  • 255 g Coconut Oil (any cold pressed coconut oil from the supermarket is fine)
  • 130g Whole Milk Yogurt (how to make it here, or shop bought is fine)
  • 130g Water (Distilled, Rainwater or Tap)
  • 116 g Lye (aka Caustic Soda or Sodium Hydroxide)
  • (if liked) essential oils to add at trace
    1. Mix the yogurt and water together until thoroughly combined. This is easy to do if you've made the yogurt and it's still liquid. If it's shop bought, be sure to mix thorough with a whisk until no lumps remain. Put into ice cube trays and freeze.
    2. Melt the coconut oil in a stainless steel bowl over a pan of hot water. Remove the bowl from over the pan, add the cold olive oil and allow to cool to between 90 and 110 degrees F (32-43 degrees C).
    3. Put the yogurty ice cubes into a glass vessel. Wearing goggles and gloves, add the measured lye to the yogurty ice cubes (NEVER THE OTHER WAY ROUND) in a well ventilated area - I always do this outside. Stir gently to avoid splashing until the ice cubes have melted and the lye is fully dissolved. Leave to cool to between 90 and 110 degrees F (32-43 degrees C).
    4. When both the oils and lye solution are between 90 and 110 degrees F (32-43 degrees C), put on your goggles and gloves and add the lye solution to the fats and oils. Stir gently with a spatula, make a note of the temperature.
    5. Mix with a stick blender until trace is reached. You will know it has been reached either because drizzling the soap over the surface leaves a 'trace' and/or because the temperature of the soap has gone up by a couple of degrees. Quickly stir in the essential oil(s) if using.
    6. Pour the soap into the mould, tap to level it off. Put it uncovered in the freezer for 30 minutes.
    7. Then transfer the soap to the fridge and leave, uncovered and undisturbed, for 24 hours.
    8. Turn out the soap, cut into bars. Leave in a well ventilated area for 1-2 months to cure, on some kind of rack if you have one so the air can circulate around the bars.

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