• Native Nut
  • Native Nut
  • Native Nut
  • Native Nut
  • Native Nut
  • Native Nut
  • Native Nut

A Really Simple Natural Soap Recipe

There are heaps of natural soap recipes on-line but even though I studied chemistry to year 12 and beyond (many years ago I might add), as a beginner I found the recipes hard to follow. Many started to get into percentages of this and that but were often not very clear, and they often talked about technical things like superfatting - it was as if they were designed to frustrate.

So I am going to share a basic soap recipe that will make about 12 bars of soap depending on your mould (1.3 litres in total). I cover the method and the safety aspects you need to be aware of if you want to give it a go without having to buy a soap starter kit.

This is what they call a COLD PROCESS soap…. which seems odd to me because the mix does get quite hot, however it does mean you don’t have to cook your oil or soap at all, despite what some folks might tell you.

Before you start you will need some equipment…

Firstly safety: A good apron, a pair of rubber gloves and safety glasses, you might also want a face mask to be extra careful but if you are generating of fumes you have done something wrong! Wear sensible, low shoes with a covered toe.

Equipment: An accurate digital balance or scales, a 250ml conical measuring cylinder, two 2 litre measuring jugs, a teaspoon, a couple of large yoghurt pots, a kitchen thermometer (optional), a stick blender, a couple of plastic cake making spatulas, a mould, a food protector, a large towel or throw, a wire cooling tray and greaseproof paper. 

I don't cover my benchtop with newspaper, but I do remember being all fingers and thumbs to start with, so it is probably a good idea until you are feeling more confident.

Now let’s get down to business.

I have chosen a simple un-fragranced Castile (or olive oil) soap. I tried to add fragrance and herbs quite early on and was then terribly disheartened when the soap didn’t come out like the picture in the recipe, so in the end I went right back to basics so I could master the process first. I have added a few tips at the end...that might help.

Make sure your mould is big enough to hold all of your soap mix, no leftovers allowed! With this recipe you can simply halve the ingredients if only have a small mould but it means you need to be extra careful with your measuring because an error of 1gm in 475gm is greater than an error of 1gm in 950gm.

One of the difficult things to get right at the start is the amount of sodium hydroxide you require because all the sodium hydroxide needs to be used up in the process, because excess sodium hydroxide is a problem. In this case I have erred on the side of caution for safety, so there will be more than enough olive oil, which also means your soap will be very gentle on your skin.

For this 10 step recipe you will need:

950gm Olive oil (measured by weight, not volume)

120gm Sodium hydroxide also known as caustic soda (Diggers caustic soda crystals are available in Bunnings. make sure you read the back of pack label before opening just in case something goes wrong).

275ml Water

And that is it.

Before you start, assemble all your equipment, ingredients and make sure have your safety gear on!

So the method.

Measure out 950gm of olive oil and put this into the first jug. I try to aim for plus or minus 2gms. 

Measure out 275ml of water using your measuring cylinder and pour this into your second jug. If your cylinder is 250mls, you can do 200mls then 75mls. The amount of water is not super critical but by looking from the side of your cylinder you will get the most accurate view.

Now to measure out the sodium hydroxide, take a clean, dry yoghurt pot then very gently measure out 120gm of sodium hydroxide, you should be able to get this to within 0.1gm. The wrong end of teaspoon will help.

Very gently add the sodium hydroxide to the water. Once it has all been added give the mixture a stir with a spatula to make sure all of the sodium hydroxide has dissolved. It will get very hot, and if you add the sodium hydroxide too quickly is will bubble, spit, and give off fumes, this is why I recommend a large jug for a relatively small volume of water. NEVER, NEVER add the water to the sodium hydroxide.

Once the sodium hydroxide has fully dissolved you can gently add it to the olive oil.

Carefully mix with the stick blender. The mixture will get hotter and should become similar to yellow gravy or runny custard. This is known as trace. Keep mixing for a bit longer, but not until it turns into thick custard. 

Your soap is now ready to pour into your mould, do this carefully because the soap is hot and still caustic. The timing on this takes a bit practice, you don’t want the mixture to thin or too thick….too thin and it will take longer to go hard, too think and you soap might end up a looking a bit lumpy...it's not the end of the world. 

Now cover your soap mould with the food protector and then drape the towel over the food protector, this will help keep the soap at day time room temperature and ensure the reaction reaches completion. You may need to switch on a heater to keep the temperature up overnight.

Leave this for at least 24 hours, by which time your soap should be hard to touch. 

Remove from the mould and place on a wire cooling tray in a warm, dry place for 3-4 days.

 I cover mine with a clean tea towel. After this time I transfer the soap onto greaseproof paper and leave for about a month to dry out and cure. 


If you don’t want to use equipment from your kitchen, have a rummage around in your local Op Shop, I have found really useful polythene 2 litres jugs for just a few cents.


You can buy a balance or digital scales on-line for about $20 and polypropylene conical measuring cylinder from an on-line laboratory supply company for about $10. To my mind they are well worth the investment because whilst you could use standard kitchen scales they are not very accurate and the more accurate your measurement the more confident you can be that your soap will be a success.

My pocket balance measures in increments of 0.1gm up to 500gm, and my 250ml polypropylene measuring cylinder measures volume in increments of 5ml.


I use a large clean dry yoghurt pot to measure my oils. I pop it one to the balance set the balance to zero (tare) and then measure out the oil, 500gms then 450gms. You can work out how much oil made it into you jug by simply popping the pot back on the scale and subtracting the amount left from the amount you started wirh. I use the same trick for the sodium hydroxide.


Rather than put your mucky spatulas and blending stick on to the benchtop, pop them into a jug, then they are easy to get hold of and any soap mix is contained, which makes clearing up much easier. 


Many recipes tell you to warm up your oil, and cool your sodium hydroxide solution until they are the same temperature. This is NOT necessary provided you are working with an oil that is liquid at room temperature and you are using a stick blender, as the action of the blender will very quickly equalize the temperature. In fact the hotter sodium hydroxide solution it is the more quickly the reaction will go, so if you are not confident then let the sodium hydroxide solution cool down to say 60oC before adding, if you opt to do this you will need to stir for longer that’s all.


If you want to add fragrance I would suggest between 10 and 20mls, depending on how smelly you like your soap, which you add after your soap has reached trace and before you pour. Measure it out in advance and make sure you mix it in well before pouring.


For a mould I would chose something like a silicone muffin mould or you can buy a mould from one of the many on-line soap supply companies. I would avoid the clear plastic Milky Way moulds because they are simply too stiff and getting the soap out of the mould can be a nightmare.


If you are using a silicone muffin type mould when you remove the soap from the mould work around the outside and then tackle the middle.


You don't really want any raw soap mix to go down the sink, so wait until the mix has hardened off before washing up, and then wear rubber gloves and use PLENTY of water. I often wash up when the washing machine is running, because the water from the washing cycle helps dilute the soap mix even more.

We like to keep things simple so we chose to fragrance each of our soaps with a single essential oil. All of the essential oils we have chosen have some antiseptic properties.

We only use 100% pure essential oils. Some people do occasionally find their skin reacts to some essential oils, so if you think you might be sensitive to any of our fragrances l you should test the soap on a small area of skin before use.