How to Make Vegan Natural Soap (Cold Process Method)
Curious about making your own soap at home?
Cold process soap making is the traditional method used to create natural soap from scratch. It’s a creative, hands-on hobby — and a fascinating way to understand how real soap is made.
In this guide, I’ll walk you through a simple beginner-friendly recipe and explain how the cold process method works. This is not the recipe we use for our Good Soap bars (those stay top secret!), but it’s a reliable starting point if you’d like to try making your own at home.
There are endless oil combinations, colours, botanicals and essential oils you can experiment with. For this tutorial, we’re focusing on a balanced, basic recipe — one you can customise once you understand the fundamentals.
What Is Cold Process Soap?
Cold process soap making is the original, traditional method of soap production.
It involves combining oils or fats (plant-based in this recipe) with sodium hydroxide, commonly known as lye. When these ingredients are mixed together, they trigger a chemical reaction called saponification.
During saponification, the oils and lye transform into soap and natural glycerin. This process begins immediately but continues over the next 24–48 hours.
Once poured into a mould and set, cold process soap must be left to cure for 4–6 weeks. During curing:
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Water slowly evaporates
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The bar becomes harder and longer lasting
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The soap becomes milder on the skin
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All lye is fully transformed through the reaction
By the end of the curing period, no active lye remains in the finished bar.
Cold process soap making requires safety equipment, careful measuring and patience during the curing stage. If you’d rather skip the waiting time, you can explore our ready-made cold process soap bars — crafted in small batches and fully cured for you.
Before you start you will need:
- Safety goggles
- Gloves, washing up gloves are fine
- 2 x thermometers
- A pan, or a bowl - use hob or microwave to melt your oils
- A jug, plastic or glass is fine
- Flat digital scales
- A hand held blender, the type you use to blend soup in a pan
- Access to water
- Spoon to mix lye into water
- Ladle to get soap into your mould
- Apron to protect your clothing
- Moulds, silicone moulds are best, they are washable and reusable and nice and flexible to push soap out of once set
- A bottle of vinegar is handy to have close just in case you splash any lye onto your skin - it's worth being prepared
The ingredients you will need are:
- Tap Water
- Oils (in recipe below)
- Lye - Sodium Hydroxide* (you can buy a small pouch)
* Safety notes - caution this is an alkili powder that when combined with water becomes extremely caustic, do not get any on your skin, wear gloves and goggles at all time when handling. If any is splashed accidentally on your skin do not rinse with water, apply vinegar first to neutralise and then wash thoroughly off your skin * When added to water Lye gives off fumes so work in a room with appropriate ventilation, window wide open or back door open if possible, take care not to inhale the fumes as you mix the lye into water.
Basic Recipe:
This recipe will make roughly 42 ounces of soap before it's cured (it will get a bit lighter in weight during the curing process) If you want less or more soap adjust by doubling or halving each ingredient exactly.
- 12 oz Olive Oil
- 8 oz Coconut Oil
- 4 oz Castor Oil
- 3 oz Sunflower Oil
- 3.8 oz Lye
- 10.26 oz Water in a jug
- Add your Lye to the jug of water, please remember safety points noted above. This mixture will get extremely hot, sometimes up to 180 degrees F or more
- Melt your oils all together, you'll want to make sure the temperature exceeds 130 degrees F
- Put your thermometers into your mixtures, one in the lye and one in the oils
- Plug your electric mixer in ready
- You will need to get the temperatures both to within the range of120-130 degrees F so watch the thermometres.
- Tip, if your oils cool faster than your lye you can pop the jug of lye inside a bowl of cold water to cool it quicker.
- When both mixtures are showing in the correct temperature range, between 120-130 (preferably towards the top end of the range) then pour the lye mixture into the oils and give a whizz with the mixer, don't over mix, it should be blended and look like runny custard!
- Ladle the mixture into your moulds (or mould if you are using a block mould)
- Leave to set overnight in the mould, the next day they will be ready to pop out of the moulds and leave to cure. Place them on white greaseproof paper with gaps inbetween the bars to allow for airflow. If you've used a block you can slice your soap after about 36 hrs ready to cure.
- Leave to cure for 4 weeks, your soap will then be ready to use
Adding essential oils:
If you are adding any essential oils then put them in at step 7. If adding essential oils to your recipe be aware that the total measurement of essential oils should not exceed 3% of the recipe total, so in this recipe 1.25 oz would be the correct amount.
We hope you have enjoyed learning a little more about how to make cold process soaps, it's a fun thing to do! If you still don't fancy having a go you can find a variety of soaps that we've made below!
Article written by Dawn Rhodes, owner of The Good Soap - Let's Go Back To The Bar