This Soleseife soap recipe uses sea water to make smooth, hard, and easy to un-mold bars.
Soleseife is a fancy European (German) name for sea salt soap. Not the kind of soap that has actual pieces of salt in it, but soap that’s made with brine – salt dissolved in water. There are two main ways to make it yourself: with homemade brine or you can make natural sea water soap.
Salt water soap is smooth, hard, and easier to get out of molds. Many cold-process soap recipes can be converted into a Soleseife recipe just by replacing the water with salt water.
Benefits of Sea Salt Soap
There are several reasons that you’d use brine in soap but the most useful is that it shortens the cure time. It also makes your soap harden a lot quicker which can be useful for recipes that are soft and hard to get out of the mold. Castile (olive oil) soap can be very soft and sticky at first but the addition of salt can make popping it out of molds a lot easier.
Most people have heard of the therapeutic powers of Dead Sea Salt. Sea salt of any kind can be beneficial for skin and is said to balance oil production and control bacteria. Both reasons make it a great addition to soap and skincare products for acne. It’s great for any skin type though!
Another thing that I love about making sea water soap is that you can collect it yourself if you live near the beach. That makes it extra special and local but just make sure that it’s clean water and not polluted.
How to make Soleseife Sea Water Soap
This recipe creates six bars of hard, white soleseife soap. It has a super-fat of 6.5% and the lather is creamy and the bubbles fine. There is no scent of sea water in the final bars if you choose to make your soap unscented.
69g (2.4oz) Sodium Hydroxide (Lye)
124g (4.37oz) Sea water or brine
150g (5.29oz) Coconut oil
300g (10.58oz) Olive Pomace oil
25g (0.88oz) Castor oil
25g (0.88oz) Shea Butter
1.5 tsp Peppermint essential oil (optional)
6 drops Grapefruit Seed Extract (optional)
Step 1: Sea Water or Brine
You can either collect your own sea water or make brine, it’s up to you. Sea water soap will be made with water with a 3.5% salinity but when you make your own brine you can create a solution of up to 25% salt. The term soleseife can be used for soap made with sea water or your own homemade brine.
To make a brine with the same salinity of sea water, measure 4.5g (0.16oz) of sea salt or dead sea salt into 124g (4.37oz) hot water. Stir until dissolved and allow to cool to room temperature. Create a stronger brine by adding more salt. Don’t be haphazard with how much you add though. Measure it out precisely and don’t go over a 25% salinity. It’s possible that your soap will turn out crumbly if you add more than this.
Step 2: Make the Lye Solution
If you’ve collected your own sea water, let it settle for at least an hour so that any sand or particles have a chance to settle. Put on protective eye-wear and gloves and measure the amount you need into a heat-proof plastic jug. Next pour the pre-measured lye crystals in. Read more about lye safety and precautions over here.
Stir well in a ventilated area such as an open door, window, or outside on a table. Allow to cool by placing the jug into a basin of water.
Step 3: Heat the Solid oils
Pre-measure the coconut oil into a stainless steel pan, the shea butter into a heat-proof microwavable container, and the liquid oils into a jug.
Heat the coconut on the hob over low heat until it’s completely melted. Then add the liquid oils (castor and olive oil) and give it all a good stir.
Take the temperature of the pan of oils as well as the lye-water solution. You’re aiming to get them both to around 125°F (52°C). The lye-water and the oils should be within five degrees of one another when you mix them in the next step. So if the oils are 125°F (52°C), then the lye water should be anywhere between 120-130°F (48-54°C)
Step 4: Melting
Melt the Shea butter in preparation for step 6. You can either do this in the microwave or on the stove top. With either, keep a close eye on it since it will melt a lot faster than you think.
In a microwave heat for 15 seconds at a time and stir — repeat until liquid. On the stove top you can heat on very low heat in a small saucepan. Don’t take your eyes off it until it’s fully melted though since it can go from melted to sizzling hot in a heartbeat. When the oil is melted, set it aside off the heat and move on to the next step.
Step 5: Mix the Lye Solution with the Oils
When the temperatures are right, pour the lye-water through a sieve (to catch any lumps of undissolved lye) and into the oils. Now comes the blending part. It’s easier to see it done in a video so you might want to check out my video for this soap recipe. It’s a different recipe but the ‘Tracing’ step is the same.
Using the stick blender while it’s off, stir the pot of oils and lye solution together. Next, place the head of the stick blender against the bottom of the pot in the center of the pan. Turn it on and pulse for a few seconds and then turn it off and use the stick blender as a spoon to stir the mix together. When the stick blender is on, it’s far better to keep it in one stationary place. Moving it around for small batches can create a mess, depending on how large your pan is.
You’ll continue pulsing and stirring until the batter hits ‘Trace’. This is when the soap begins to thicken slightly to the consistency of warm custard. If you take the stick blender out and dribble the soap batter into the pan, the dribbles will create a texture on the surface.
Step 6: Extras
When the soap batter is at ‘Trace’, you can stir in the melted Shea butter and your extras. Peppermint essential oil will give your soap a zingy scent and feeling and it’s also great for oily skin.
Grapefruit seed extract is an antioxidant and will help keep extra oils in the recipe from going rancid over time.
Step 7: Molding
When the extras are mixed in, pour the soap into your mold. If you’re using the mold that I’ve used then you can leave it on the counter, uncovered, to harden up. If you’re pouring your soap into a loaf mold, you might want to pop it in the fridge to cool and harden. This will help ensure that the bars are white all of the way through and there isn’t a circle of slightly darker (Gelled) soap in your bars. If this does happen, it’s just cosmetic and the soap will be completely fine.
Step 8: Curing your Soleseife
You can take the soap out of the molds after 24 hours. Cut your bars if they were in a loaf mold. Now place them spaced out in an airy place out of direct sunlight and traffic. Leave them there to cure.
Curing time for soleseife soap can be shorter than for other cold-process soap at just 2-3 weeks. Salt helps speed up the process by drying the soaps out so the more salt you use, the shorter the curing time may be. Sea water soap has a lot less salinity so I’d recommend that you cure it for at least three weeks.
After the curing time is up, the soap is ready to be used. The shelf-life is completely dependent on the closest expiration date of the materials you used to make it with — if the bottle of olive oil you used has an expiration date of next month on it then that’s your soap’s shelf life. Use it quick! It’s far better to use oils and ingredients that aren’t about to go rancid though so keep an eye on the best-by dates. For full instructions on how to cure handmade soap head over here