How to make Soleseife: a Natural Sea Water Soap Recipe

How to make Soleseife: a Natural Seawater Soap Recipe

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Make this Soleseife soap recipe with seawater to create smooth, hard, and easy to un-mold bars. Use water collected from the beach or a homemade salty brine.

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 seawater 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 saltwater.

How to make Soleseife: a Natural Sea Water Soap Recipe

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.

How to make Soleseife: a Natural Sea Water Soap Recipe

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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 seawater 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: a Natural Sea Water Soap Recipe

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 seawater 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)

Special Equipment needed
Digital Thermometer
Digital Kitchen Scale
Stick (Immersion) Blender
6 Cavity silicone soap mould

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.

How to make Soleseife: a Natural Sea Water Soap Recipe

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 stovetop. 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 stovetop 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. Seawater 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


  1. Can seawater be used in a soap recipe where potassium is collected from bananas or other natural resources?

  2. Hi!
    Should I worry at all about sea water that may have elevated marine toxins in it? For example, when our shores are closed for crabbing and clamming due to the toxins, should I not collect water for soap? It is a toxin produced by marine algae so I think it may be different from bacteria, which you mentioned in an earlier comment reply that it would be killed by the lye solution.

    So my question is if I have to worry about Domoic acid, would that affect soap making?

    Maybe it would be weird since it’s an acid? I am super curious about what you think, even if you don’t have a definitive answer! Seems complicated.
    Thank you!

  3. Hi Tanya,
    What a great post, I’ve learned so much so far with your tutorials and such detailed explanations, thank you very much!
    I’ve tried quite a few of your recipes with much success :)

    Just 2 questions:
    The water you used to produce the salty brine, is it distilled, filtered or regular tap water?
    Would using homemade salty brine or sea water work ok to reduce the unmolding and curing time of Castille soap or other soft soaps such as the one with Carrot purée?

    Thank you very much for your time!

    1. Hi Flor, it’s best to use distilled or filtered water in soap making. Minerals, chlorine, and other things in tap water can affect the shelf life of the soap and how much soap scum it creates.

      Salty brine could theoretically help with other recipes too. The best way to find out, for the recipe you have in mind, is to make a small batch and see :)

  4. Hi Tanya,
    I am interested in soap making, but have dexterity issues and as such want to start making soap with Melt and Pour as it would cut out what I term the most “dangerous ” part ie using Lye.
    So now to my question. What parts of your recipe would I need to add to end up with a finished bar of soap.
    Thank you.

  5. Hi Tanya,

    I love your recipes and have made wonderful moisturizing soaps.

    This is the first time i am trying your method of folding in the shea butter at trace. I ran your recipe through soapcalc and noticed that the lye amount was for the full oil amount inclusive of the shea that was mixed at trace.

    With your soleseife recipe, the bars feel so lovely on the skin during shower and my skin did not feel squeeky during the shower, which I love. However, i noticed that my skin got really dry after 5 times of showering.

    I wonder is this perhaps the nature of a soleseife or if it is due to the lye amt? what if i use a lye amount that is just to saponify the oils stated sans shea? would that then be better?

    i would love to hear from you soon <3

  6. I’ve just cut my first salt water (4% salinity) soap and it’s lovely. Thank you very much. Can’t wait for it to cure to try it out.

  7. Is regular ocean water really safe? I live in a beach town with a beach that ranks pretty high in cleanliness, but, what if a fish died and a couple of kids peed while swimming or, i don’t know… I’m probably overthinking it, but there’s a reason we want to shower after going to the beach. Is there a way to check the “purity” of the seawater collected? Thanks for the recipe, can’t wait to try it!

    1. Maggie, I don’t think any bacteria would survive being suspended in a caustic solution. Soap also has a final pH of between 8-11 which is also inhospitable to bacteria. They prefer neutral to slightly acidic whereas soap leans more alkaline. Hope this helps :)

      1. Hey lovelygreen plz say me required ingredients for olive oil soap with salt
        but should i use sea salt or pink himalayan salt which salt because mam i only want to add only 4 ingrdients
        1 olive oil 1000gm
        2 sea salt or pink himalaya salt( which one & how many grams )
        3 lye Gms?
        4 water &(.which water what it should mentioned in water distilled or something)

        Plz reply im trying to get but in youtube i cant find one to make it with salt
        they say u should not add salt
        & i dont want to use coconut oil or any oil just olive not even shea butter just lavender essence & dry rose petals to it

        So plz reply me & tell me how to make it i beg u or anyone plz reply md im new to this im searching from 1/2 year..

  8. Hi Tanya,
    I love your explanations and your videos. Is the soaps are dangerous while it curing? ( I live in a small apartment and there is no other place for curing only our living environment) . Is there any way to know when the soaps completely cured? And how can I know the final soaps ph level? Merci for your answers

    1. They are not dangerous while curing and actually scent your room (or apartment) really nicely during that stage.

      All soap has a final pH of 8-11 but I don’t tend to test them often. The only time I think it’s worth testing pH is if you’re uncertain about the amount of lye in the recipe. Basically, in the case where you’re making it and think you accidentally put in too much. But even then, testing for pH is tricky and often inaccurate and the final pH in many cases will give you a normal pH level even if there’s excess lye in the soap. Also, the pH you get won’t even indicate how mild the soap will be anyway. My advice with testing pH: don’t bother unless you see something weird happening. Meaning liquid oozing from the soap, crystallization, or white clumps.

  9. Wonderful tutorial @Lovelygreens!
    I’ve just made it for the first time with a 20% brine solution Sunday night. I was able to unmold it the next morning. It’s now Wednesday afternoon and the soaps have been in a drying chamber with a dehumidifier set to about 44% humidity. They look really nice!
    I have just a few questions as this is the first soap I’ve ever made if you have a moment…
    1. how soon are the soaps safe to be handled without gloves?
    2. there’s a tiny bit of glycerin sheen on the outside in a few places…ok?
    3. you gave the curing time estimate of 2-3 weeks (with 3 weeks suggested for ‘sea water’). since I’m using a much higher concentration of salt (20%) would you think that 2 weeks would give me a complete/ready to use cure?
    I’m intrigued with your site and will check into your lessons…
    Thank you!!!

    1. That’s quite a salty solution. My guess is that it’s probably the reason you have a bit of glycerin sheen but I wouldn’t worry about it too much. See what the bars look like after the curing time and try making it again using a weaker solution.

      Saponification is mainly finished after 48 hours. I feel comfortable handling fresh soap after this time. As for your own cure time, you can measure it accurately by taking the weight of one of your bars when you unmould it. You’ll know how much water is in it from your recipe. Then work out the ratio of your other soaping ingredients to the water — you could end up with a percentage of around 20% moisture in the bar. Weight and take measurements every four days or so and when it hits about 9% moisture then it’s ready for use.

  10. Thank you for sharing your recipe. Can’t wait to try it. How long do you chill in fridge if you pour into loaf mold? Thanks

  11. Thanks for sharing your recipe. This will be my first time making this. If I pour into a loaf mold, how long does it need to stay in the fridge? Thanks

  12. I love making 100% CO brine soap but also want to have a go at Castille which I’ve not done before in any form. I see you mentioned that the brine would help it (olive oil soap) harden and unmold quicker but does it have a detrimental affect on the finished lather? Love your blog, thanks so much for the gorgeous inspiration x

    1. I’ve not noticed any inhibition of lather when using salt in soap. If you were worried about the amount you’re using, make a couple of test batches to see. You could also add a touch of sugar or honey to your recipe to help boost lather.

  13. Oh I have another question please😊 the closest sea to me is the dead sea, but it’s extremely salty I don’t think it’s usable in soap making, so could you please tell me how to prepare the brine! Is it like pickling brine?

      1. Hi again, I finally tried this soap recipe :) I absolutely love it, my husband stopped using any other soap :) thank you so much for sharing it.

  14. Hi, can I use extra virgin Olive oil instead of Pomace Olive oil. Here in Jordan we only have one kind of Olive oil (extra virgin). Thank you

    1. Of course! The colour of your bars might not be as white since EVOO tends to be darker and greener. If you don’t have an issue with that then crack on.

    1. Yep, adding salt to the soap batter does add exfoliation. It can also cause the soap to weep a bit — I’ve seen this happen with one of my batches. Dissolving it first helps if you don’t want either :)

    1. I think cold process is better for this soap recipe. I made this recipe with hot process and it hardens very quickly, to the point where it’s not pourable or even spoonable, it broke into chunks after it cooked for 30 minutes. I added more water and tried to mix it again and it did become more workable, but nothing like the lovely smoothness of the cold process bar pictured here in the recipe. Still a really nice and creamy bar of soap, but I would stick with cold process for the best results!

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