Why water? What it does for soap making

[littlboz]

Water, roughly about 30% of your total oil volume, is used to dissolve lye. Does it serve any other function? In my experience more water makes the bar softer.

Edit: Is it needed to help catalyze the saponification of lye and oil?

 

[judymoody]

Yes, without a sufficient amount of water, the chemical reaction of saponification won't happen properly.

Your bars will harden as some water evaporates during cure. HP can be used sooner than CP but it also benefits from a decent cure.

 

[Pentazole]

Water is not needed for saponification, and quite often saponification can occur in the complete absence of water, such as saponification in alcohol (the mechanism of saponification does not involve water). Water is asked for in large percentages to make it easier to work with - low amounts of water and you risk several safety issues, such as overheating while dissolving the lye, and too quick of a reaction with fat leading to overheating and your CP turning to HP without your wanting it. In any case, mass produced toilet soap generally contains 10-20% moisture, so having water in your soap isn't all that bad. I use 15% water per total oil mass, and I have no trouble. Anything less than that and the NaOH will recrystallize as soon as the lye solution cools down, which is not a good thing. I did have an accident once with a 40 pound batch that heated out of control and was completely lost (coulda been saved but contained honey, and the honey burned).

Try a small batch with 15% water, it's not too bad to work with, but please be very careful - your lye solution is extremely concentrated.

 

[carebear]

you lye needs to be dissolved, and the solubility will depend on the temperature so if you are letting your lye solution cool to room temp you need about as much water as lye - and more water increases the likelihood of achieving gel.

play and decide for yourself.

(yes, you could dissolve it in ethanol instead of water, but why would you?)

 

[carebear]

mass produced toilet soap isn't generally made by our methods, by the way. usually (tho not always) the soaps are compounded from refined salts of fatty acids and other components. or are cooked using much different methods and actually an excess of water which is removed during processing (less common).

 

[soapbuddy]

Water evaporates as the soap cures. Unless you added way more then necessary, the water will cure out and the soap should harden. I won't use alcohol in CP soap as it makes the soap seize. The exception is beer which I boil off the alcohol. Always run any recipe through a lye calculator. The Sage lye calc, for example, gives you a water range to work with.

 

[Pentazole]

Ok of course I know that commercial toilet soaps are made in a different way than CP soap, and I wasn't recommending that anyone makes CP soap using alcohol as solvent I was just trying to make the point that water is not needed for saponification, that's all. The fact that plain old alcohol CAN be used, means water is only added for convenience.

I live in a country where it's so humid that my dishes have to sit in the dish rack for two days to dry out. You can imagine that if I use 35% water in my soaps it would take 5 years for a bar to cure/dry. Therefore I'm a proponent of 10-15% water.

 

[soapbuddy]

Ok of course I know that commercial toilet soaps are made in a different way than CP soap, and I wasn't recommending that anyone makes CP soap using alcohol as solvent I was just trying to make the point that water is not needed for saponification, that's all. The fact that plain old alcohol CAN be used, means water is only added for convenience.

I live in a country where it's so humid that my dishes have to sit in the dish rack for two days to dry out. You can imagine that if I use 35% water in my soaps it would take 5 years for a bar to cure/dry. Therefore I'm a proponent of 10-15% water.

You have to use at least minimum water required in a soap calc for the lye to dissolve. Otherwise you will end up with undissolved lye crystals in your soap with dire consequences. Water is used as a carrier and it is needed for handmade soaps.

 

[littlboz]

Conclusion: water as a solvent for lye

Thank you everyone. My conclusion is that water acts as a solvent only for the lye. Water does not mix with oil and it only acts on the lye as a carrier so the lye can be evenly distributed in the oil. The lye and oil mix to form trace and the water just kind of floats about and evaporates a bit during the curing process.

 

[krissy]

i may be wrong and so i am asking... I was under the impression that you needed to use at least as much liquid as you do lye in order to allow the lye to dissolve fully? that is why i never would go below a 1:1 lye to water ratio. :?:

 

[carebear]

Krissy, you do if you intend to bring your solution to room temp or if you are adding to cool oils because there are limits to the solubility. If you soap hot solution and hot oils you can go with a higher concentration. But then you are asking for problems because the higher concentration increases risk of seizing and the heat does the same... (at 75C you can have just over a 1:1 ratio). When the solution is hot you can get more lye into solution but run the risk of it falling out of solution as it cools.

But if someone wants to do it, and manages it then more power to 'em. Just not something I recommend - especially for beginners.

Littl, the water is a solvent for the lye - so yea it's a carrier, but at the molecular level. Trace is essentially advanced emulsification where some of the reaction has already occurred so the soap acts as an emulsifier.

 

[green soap]

Water slows down the saponification reaction.

If you are making 100% olive oil soap, leave it at 1:1 water lye ratio.

If you are making 100% coconut oil soap, increase the water to the maximum in SoapCalc.

For everything in between, use water accordingly. If you have an EO that speeds saponification, add more water.

 

[carebear]

If you want your soap to gel, don't use 1:1.

Also, even with OO, I don't choose to make a 50% solution. I find 40% easier to manage, even after a hundred batches of pure castile soap.

 

[Soapy Gurl]

What is recommended to get gel? I CPOP and soap and RT sometimes and warm other times. I am so exact, I know!