Water and koh/oil reactivity?

[Sapo]

If one was to...increase drastically the amount of water used when making paste, would the reaction between KOH and the oils still eventually take place? Paste probably wouldn't form... but still? Any guesses how long it might take?

And what about if the paste is already made, and has been cooked for e lenghty amount of time, but the darn thing was apparently mismeasured (crappy cheap scales!) and you have excess fatty acids present; would dissolving it in a bit of water, to make additions of KOH easier be at all wise?

Im currently in the second situation, checking if there is a fix other than dissolving the paste in alcohol/glycerin, but also interested what peeps think about scenario #1.

If it is at all feasible, one could take #1 to the extreme and incorporate the dilution liquid into the initial recipe for the paste, and, presumably, wait XYZ amount of time and have finished LS in "one step".

#chemistrynoob

 

[Susie]

I have tried the first idea. The problem is that even using a 4:1 ratio on the water:lye takes a VERY long time to get to full emulsification. There is some video floating around Youtube (I am going to work in a couple of minutes, so I don't have time to find it.) that purports to show a one step process from raw ingredients straight to diluted soap. I was not able to make it work, so I tried it going up from 3:1 ratio onward. It just did not work well at even 4:1. It requires more time and work than making the paste and then diluting. I would encourage you to try it, though, and let us know your results.

The second situation where you are attempting to fix an overly superfatted or broken soap, I would indeed dilute what I have with water (albeit less water than "full" dilution) before adding KOH/water. It makes the process much faster. It also helps if that liquid soap is warm. As soon as you see that soap go together (not be in layers any longer), stop adding KOH/water. Also, unless you are absolutely positive of the amount of KOH you lack, add small amounts and wait 15 minutes or so between additions. Better to take a little longer on the front end than end up with lye heavy soap on the back end.

 

[DeeAnna]

The usual methods of hot process and cold process soap making are designed (whether we realize it or not!) so the maker can stop mixing the soap fairly soon in the saponification process. It's not the only way to make soap -- the "boiled" method of soap making that is used on a commercial scale is a method that uses a lot more water than is typical for hot or cold process.

The downside of more water is it can take much longer for the soap batter to form a stable emulsion. Until it does form a stable emulsion, you have to keep the lye solution and fat mixed somehow or saponification will slow to a crawl. In industry, they run mechanical agitators to mix the ingredients or bubble steam through the soap batter for however long it takes.

The video Susie mentions is a small scale commercial operation. There is a continuously running agitator in their soap making tank -- that's the "secret" to their no-paste liquid soap making process.

Not to say it can't be done by a hobby soap maker. The "Andalusian castile" thread here on SMF is about soap made with a ~15% lye concentration. So give it a try and see what you think!