Diluting and Thickening Natural Liquid Soap

A 10% dilution is good for standard use though I dilute mine at a slightly stronger dilution because I still have to add the thickening.

A 10% dilution means the weight of oil and KOH would be 10% of the total water added.

I have my shampoo at 20% so I don’t have to use so much to get a good lather.  For dish washing I leave it at 30%. These things are personal preference.

When diluting the soap paste. Put it in a bowl and use hot water from the kettle and let it sit overnight.  It dissolves itself.   No mashing needed.

Use distilled water.  I use filtered water from reverse osmosis filter.  I don't know how much difference there will be if you use tap water.

Weight of Oil and KOH
x2 = 50% dilution is your paste weight.
eg If your oils and lye weigh 1000gm, top up your water till it weighs 2000gm.  It may weigh about 1300gm after cooking it with the water from initial recipe water to dissolve lye in. Use hot or boiling water and as you stir it in, the paste will thicken up and become really tacky.  I leave it for a a few hours and stir it again later or it takes too much time.

You can store this soap paste and dilute further as needed.

From there on
x1.66=30% dillution
x2     =25%
x2.5  =20%
x3.3  =15%
x5     =10%

eg. If you have 100gm of soap paste (50% dilution) and want to dilute it to 15%, multiply
100gm by 3.3 = 330gm.
100gm Soap paste    +    230gm of filtered water      =  330gm of liquid soap at 15% dilution.
Add water and let the soap paste dissolve.

Salt Thickener

I have only ever thickened my liquid soap with salt.  It is very simple and inexpensive.  It does cloud the soap a little but I am not concerned about that.  I suppose that this also acts as a preservative.  While the salt will be good for your skin it also may be a bit drying if you are inclined that way. A 2% superfat should off set this.

Make a 20% salt solution (4 parts water, 1 part salt).  When you add this to the soap it will get stringy white thickened streaks.  Just stir or shake and it will disperse become clearer.  If it doesn't go stringy but instantly cloudy whitish, something is wrong and it will not thicken.  Stop adding the salt solution and use a foamer with this soap. I add this at 4% if I have an essential oil that also thickens.

Use table salt not Himalayan or Dead sea salt.  The experts agree...and when I used Himalayan it didn't thicken but the white thickening rose to the surface.  Curiously the liquid soap cleared of all its colour. Still a good liquid soap, just not thick.

My thickened liquid soap as a gel

I see no logic in evaporating water to thicken your soap.  It won’t produce the ideal thickness but will just make it stronger and you will use it quicker.

Salt does not thicken liquid soap with a high Coconut oil content.  I think there would be little practical point to try as the best use for this soap would be as a bubble bath or cleaning soap.  It would make an excellent mechanical workshop, grease removing soap but otherwise I wouldn’t want to use this on my skin because it is so drying.

Thickening soap that is too diluted will cause curdling that floats on the top of the soap.  To fix this, add less dilute soap to bring it back. This increases the soap concentrating for the salt to work on.

Coconut oil and thickening
Higher levels of coconut oil in the soap paste will not allow the salt to thicken it.
After testing different levels and many failures, 18% coconut oil in the recipe is the highest limit I will use if I want to thicken the finished product with salt.

Castor oil and thickening.
I made soap with no coconut oil in to add to one that had too much, I made up a recipe with 25% castor oil and 75% olive oil.  In all my reading I had not seen a caution using castor oil in regard to thickening.  After many hours trying to get the soap batter to a paste I gave up and cooked it regardless.  It ended up looking like sticky mashed banana rather than the thick stiff soap paste.  The soap worked nicely diluted, but would not thicken.  Since then I found one comment that 20% might be too high.
After some testing in the kitchen I have found that soap with 15% Castor Oil will thicken but higher than that the thickening just whitened the soap and didn't thicken it.  If I left this a little while the whiteness would raise to the top and sit there

Using Borax to Thicken
I have tried using borax to thicken without success.  It turns out that if you have a "superfat" it will not work.  This is most likely the problem I have had.
As with using salt, it will not work with unless the coconut oil content is low.
Catherine Failor says that it works better with a more concentrate soap and decreases efficiency as the dilution increases.

Foamer
With new recipes and thickenings try a small amount to start with to check that it will thicken.  If it doesn't use the runny liquid soap in a foamer pump.If youI can't