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5 from 6 votes

Soleseife Soap Recipe: Natural Seawater Soap

1lb (454 g) Soleseife soap recipe creates six bars of hard, white seawater soap. It has a 6.5% superfat, a 33% lye concentration, and the final lather is creamy and the bubbles fluffy and stable. There is no scent of seawater in the soap if you choose to make your soap unscented.
Keyword salt, soap, soap recipe
Prep Time 30 minutes
Cook Time 30 minutes
Curing time 28 days
Total Time 1 hour
Servings 6 bars
Author Lovely Greens
Cost 10

Equipment

Ingredients

Lye solution

Soaping Oils

After Trace

Instructions

Soap Making Preparation

  • Cold-process soapmaking is chemistry, and this recipe uses lye. Lye is a caustic substance that is completely neutralized in the soapmaking process, but it can be harmful if not handled correctly. Please read this soap making safety guidance before proceeding.
  • Ensure that your soapmaking station is set up with all of the equipment, materials, and tools you need. Pre-measure the main ingredients using a digital scale. The coconut oil into a stainless steel pan, the liquid oils together in a jug, the shea butter in a microwaveable dish, and the lye (sodium hydroxide) into a dish. Take care to wear gloves when measuring the lye.

Prepare the Seawater or Brine

  • You can either collect your own seawater or make brine, it's up to you. Seawater 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 seawater or your own homemade salt brine.
  • If you've collected your own seawater from the ocean, let it settle for at least an hour so that any sand or particles have a chance to settle. Gently pour it through a sieve, trying to keep the settled sediment (if any) in the original jug. Measure out the amount you need for this recipe into a heat-proof jug.
  • To make a brine with the same salinity of seawater, measure 4.38 g (0.08 oz) fine grain sea salt into 121 g (4.27 oz) hot distilled water. Stir until dissolved and allow to cool to room temperature. Create a stronger brine by adding more salt. Measure it out precisely though and don't go over a 25% salinity. If you do, it's possible that your soap will turn out crumbly, or have poor lathering properties.

Make the Lye Solution

  • For full information on soap-making safety and equipment please head over here. It’s important to read it before trying to make soap the first time. Put on your rubber gloves and eye protection (goggles) and set yourself up in an area with good ventilation. Under a hob, on the doorstep, or outdoors is perfect. Pour the sodium hydroxide into the seawater/brine and stir with a stainless steel spoon. Be careful not to breathe in the fumes. 
  • Stir well and leave someplace safe to cool to 100°F (38°C). I tend to set the jug containing the lye solution in cold water in the sink.

Melt the Coconut Oil

  • Heat the coconut oil on the hob over low heat until it's completely melted. It will melt quickly so do not leave it unattended.
  • When melted, take the pan off the heat and cool on a potholder. Stir in the castor and olive oils and continue to stir every few minutes until the oils have cooled to 100°F (38°C).
  • You also need to keep an eye on the lye solution, stirring occasionally, and cool it to around the same temperature.

Melt the Shea Butter

  • Melt the shea butter in preparation for step six. You can either do this in the microwave or on the stovetop. 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 from the heat and move on to the next step.

Make Coconut Oil Soap

  • Get the soap mold prepared and double-check that your goggles and gloves are on and that you won't be disturbed for the next ten minutes.
  • When the lye solution and oils are both about 100°F (38°C), pour the lye solution into the pan of oils. Pour the lye solution against a spoon held in the oils as this will reduce air bubbles in your final bars.
  • Using the stick blender turned 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 a light 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.

Add the Shea Butter and Essential Oil

  • When the soap batter is at 'trace', you can stir in the melted shea butter and optional essential oil. Peppermint essential oil will give your soap a zingy scent and feeling and it's also great for oily skin. It's optional though and you can make this recipe without it for a mild unscented bar.

Mold the Soleseife Soap

  • When the extras are mixed in, pour the soap into your mold(s). If you're using the cavity mold that I've used then you can pour the soap batter in and leave it uncovered on the counter to harden up for a day.
  • If you're pouring your soap into a loaf mold like this one, I recommend placing it in the fridge to cool and harden. This will help ensure that the bars are pure white all of the way through. If you don't refrigerate it, there's a chance that there will be 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.

Cut and Cure your Seawater Soap

  • I recommend taking soleseife soap out of the molds after 24 hours and it should pop out pretty easily. Cut your bars if they were in a loaf mold and it's best to wear gloves when handling soap at this point. Most of the saponification is complete but there may still be a tiny amount of lye in the soap. Plus fingerprints.
  • Now place your soleseife bars spaced out on a sheet of wax paper in an airy place out of direct sunlight. Leave them there to cure for a month. During the curing process, the bars will harden, lose water, finish saponifying, and develop that all-important crystalline structure. More information on curing is here.
  • At the end of the cure time, these soaps will be hard and white. For full instructions on how to cure handmade soap head over here
  • Once made, your soap will have a shelf-life of up to two years. Check the coconut oil best-by date though, since that will be your soap's best-by date too!

Notes

Lastly, are you a beginner soapmaker looking for more guidance on how to make handmade soap? Enroll in the Natural Soapmaking for Beginners Online Course to get up to speed quickly. You'll learn all about soap ingredients and equipment and be guided through step-by-step soap recipe videos.