Salt saturation

[Oxbow]

Hello,
This is my last topic about hardening a soap. I think generally handmade soaps aren't as hard as hot-processed industrial soap and I am trying to fix that.

I know that added salt to the lye can make a harder bar. On internet, I have seen many sites about how much salt you should add (0.5 teaspoon per 100 g, etc.).
But... what I think is : if you add first the NaOH and it solubilizes completely, then you can add salt untill it reaches saturation (= the salt no longer solubilizes and falls to the bottom)
Then, when you add the lye-water, you can incline the container so that the solution will flow but not the solid salt at the bottom.

So you have added the maximum salt possible and you have the harder bar possible and that's the goal.

The only thing I am affraid of, is to precipitate NaOH by doing this. But I think it won't. What do you think ?

 

[AliOop]

Salt inhibits lather. Too much salt = not very nice soap.

 

[Obsidian]

Even a salt bar made with brine isn't as hard as commercial soap.
Commercial soap usually contain synthetic detergents and is ground then pressed under a lot of weight. Thats what makes those bars so long lasting.
Handmade soap is just different. Different formulas and different processes, you can't compare the two.

 

[DeeAnna]

...what I think is : if you add first the NaOH ...then you can add salt untill it reaches saturation ...
...when you add the lye-water, you can incline the container so that the solution will flow but not the solid salt at the bottom....
The only thing I am affraid of, is to precipitate NaOH by doing this. But I think it won't. What do you think ?

Okay, so I think you are saying you would do this --

Make the lye solution (NaOH + water) and then add salt to that lye solution. And then you would pour the liquid NaOH-salt-water solution into the fats, but you would avoid pouring any of the solid salt crystals into the fats.

Am I right?

It's an awkward way to do this, but if that's what you want to do, go for it. Be aware you will not get all of the NaOH into the fats because some of the lye solution will remain with the salt.

Also you won't just get a harder bar with that much salt; you get a bar that also lathers less, as Obsidian and AliOop have pointed out.

Commercial soap, meaning the kind made in huge quantities, is not made with a hot processed method. Commercial soap is made with what's called a boiled method or other high-volume industrial methods that we cannot replicate. Hot process and boiled are two quite different methods.

Commercial soap is then dried and mechanically mixed and compressed, which may include "French" milling for some brands. The drying, mixing, and milling makes a physically harder bar AND all these operations create a longer lasting bar.

Adding salt to handcrafted soap might add some hardness, but I guarantee salt won't make the bar longer lasting.

"...The only thing I am affraid of, is to precipitate NaOH by doing this...."

Well, I'll tell you the NaOH will not precipitate. The salt (sodium chloride) is the limiting factor here, not the NaOH.