How to Make Marseille Soap at Home: a Cold Process Recipe, Marseille Style

To make a Marseille-style soap at home, all you need is olive oil, lye and water. It is made using the cold process, in an hour, then left to cure for at least six weeks. Here are two recipes to the gram, pure olive or olive and coconut, and what sets them apart from a Marseille soap cooked in a cauldron.

At a glance

• Ingredients: olive oil, coconut oil (optional), sodium hydroxide (lye), demineralised water
• Working time: about 1 h, plus 48 h in the mould
• Curing: 6 weeks minimum
• Yield: 500 g of oils make about 6 bars of 100 g, depending on curing
• Difficulty: easy, provided you respect the quantities and safety rules

Traditional Marseille soap: cooked in a cauldron

In 1688, a royal edict required Marseille soap makers to use “pure olive oils, with no mixture of fat”. Even today, traditional Marseille soap is made from vegetable oils and cooked in a cauldron using the Marseille process, over several days:

1. Pasting: the oils are heated with lye and begin to turn into soap
2. Salting out: salt water is added, the soap rises to the top, and the glycerine-laden water is drained off
3. Cooking: the paste is cooked with lye until all the oils have been converted
4. Washing: the paste is washed with water to remove excess lye
5. Fitting: a final rest separates the pure soap from the impurities

The soap is then poured, dried, cut and stamped. This long, demanding process belongs in a soap factory: at home, you make a Marseille-style soap, using the cold process.

Equipment

• Digital scales accurate to 0.1 g, essential for weighing the lye
• Safety goggles, nitrile gloves, long sleeves
• A stainless steel or hard plastic (PP or HDPE) container for the lye, ⚠️ never aluminium
• A large stainless steel container for the oils, a silicone spatula, a stick blender
• A kitchen thermometer
• A silicone mould, or a box lined with baking paper

Ingredients and quantities

Two versions. The lye quantities are calculated for a 5% superfat (you use 5% less lye than all the oils would require, to keep a safety margin) and a 33% lye solution.

Pure olive soap lathers little and hardens slowly. The olive and coconut version lathers more and hardens faster. ⚠️ Weigh everything, oils included, weigh the lye to 0.1 g, and never change an oil without recalculating the lye: our free soap calculator does it for you.

How to make it, step by step

1. Set up your workspace. Goggles and gloves on, window open, children and pets out of the room, ingredients weighed in advance
2. Make the lye solution. Pour the lye into the water, never the other way round, and stir without breathing in the fumes: the mixture gets very hot. Let it cool to around 35 to 40 °C
3. Prepare the oils. Coconut oil is solid below 25 °C: melt it, then mix it with the olive oil. Aim for the same temperature as the lye
4. Mix. Slowly pour the lye into the oils and blend in pulses, stirring with the spatula in between
5. Wait for “trace”. The batter reaches the consistency of custard. With pure olive oil, this can take 15 to 20 minutes, sometimes longer
6. Pour into the mould. Pour into the mould, tap it to release air bubbles, then cover with a piece of cardboard and a towel
7. Unmould after 48 h, wearing gloves: the soap is still caustic. A pure olive soap may need one or two more days
8. Cut and cure on a rack, somewhere dry and out of the sun, turning the bars from time to time

Curing

Six weeks minimum. During this time, water evaporates and the soap hardens. A pure olive soap benefits from waiting two to three months. Curing does not make up for a measuring error: only an accurate calculation and precise weighing give a safe soap. Unlike cauldron-cooked soap, your soap keeps its glycerine.

Mistakes to avoid

• Pouring water onto the lye: risk of scalding splashes
• Using an aluminium utensil
• Measuring oil by volume instead of weighing it
• Changing an oil or the quantity without recalculating the lye
• Unmoulding a pure olive soap too early, while it is still soft

Safety: sodium hydroxide (lye)

Sodium hydroxide (caustic soda) is corrosive to skin and eyes. On skin: remove contaminated clothing, rinse immediately with water for at least 15 minutes, then see a doctor. In the eyes: rinse immediately under running water for at least 15 minutes and call the emergency services (999 in the UK, 112 in the EU) or a poison centre without waiting until you have finished rinsing. Store lye closed, labelled and out of the reach of children.

This soap is for your personal use. To sell it, cosmetics regulations require in particular a responsible person, a product information file with a safety assessment, good manufacturing practice, compliant labelling and notification on the European CPNP portal.

Frequently asked questions

Is homemade Marseille soap real Marseille soap?

It is a Marseille-style soap: the same vegetable oils, but made using the cold process. Traditional Marseille soap is cooked in a cauldron, then salted out and washed using the Marseille process, and poured into large slabs.

What does “72%” mean on Marseille soap?

By tradition, the figure refers to the proportion of fats used to make the soap. It is neither the proportion of olive oil nor a legal standard: according to professionals, the thresholds used today vary.

What are the ingredients of real Marseille soap?

Vegetable oils, lye and water, with salt for salting out. The Marseille tradition adds no fragrance or colourant. On the label of a pure olive soap, for example, you will read Sodium Olivate.

Why add coconut oil?

A 100% olive soap lathers little and stays soft for a long time. 20% coconut oil gives a more generous lather and a harder bar.

How long should the soap cure?

Six weeks minimum. A pure olive soap benefits from waiting two to three months: it becomes harder.

Can you use this soap for laundry?

These recipes are designed for washing yourself: their superfat can leave a slight greasy residue on clothes. For laundry, you need a recipe with no superfat.

No time to wait?

Our organic pure olive Marseille soap is cauldron-cooked in France. Also discover our antique Marseille soap, our liquid Marseille soap and our whole range of Marseille soaps. For more recipes: how to make Aleppo soap and how to make liquid soap.