I haven't done a stearic and NaOH soap. However, even at 60% stearic acid and a mixture of potassium and sodium hydroxide, I get a pretty hard bar of soap. I haven't gone beyond 50% for NaOH. My soaps with lots of stearic acid don't actually come together like the ones in the hot process soaping videos. Upon adding lye, the glycerin (this glycerin is only from coconut oil; no glycerin is present in pure stearic acid) and fatty acids separate immediately and a large amount of bright white precipitate forms in the bottom of the crock pot, saturated fat I think, a result of temperature dropping too much too quickly. This takes a good amount of work to stir back into a Vaseline-like mass, whereupon the crockpot gets turned up to high for a few minutes until the whole thing gets hot and loose enough that it is ready to emulsify. I then use the stick blender to emulsify it and bring it to a thin vanilla pudding consistency. This is trace. At this point, I start cooking, usually on high. Most hot process soaps can be cooked on low in the crockpot, but stearic acid needs to be very hot to turn liquid, so it needs to be hotter still to gel/saponify. After it has saponified, when I shut off the heat, it is a matter of 10 minutes before the soap is nearly too stiff to put into the mold. Adding fragrance/EO accelerates this a bit (as an aside, the lemongrass batch set up almost immediately after I added the oil...it is my understanding that some fragrance oils accelerate this process more than others, so I suppose it makes sense that the same holds true for EO). I let my soap sit for about 5 minutes after I shut off the heat before mixing in my EO and pouring or ladling it into the soap mold. I am making a batch tonight. I'm no photographer but will try to take some pictures to demonstrate what I'm talking about.
At any rate, Chris, I made a soap with a bubbly number of 9, as I mentioned, and it was lacking for bubbles. Very. And, back to the hardness question, I have not made anything as soft as an Italian soft soap, despite using at least 50% KOH in every batch. So I don't know for sure, but I imagine a pure sodium stearate soap would be brittle, hard, and lather into thin cream. It is interesting to note this ingredient list for Vitos, taken from Italian Barber's site: Stearic acid, hydrogenated tallow, potassium hydroxide, water, sodium hydroxide, sodium hexametaphosphate, benzoic aldehide, talc
No coconut oil, though the hydrogenated tallow would have a bit of lauric and myristic acid to contribute bubbles. Not much, though. I haven't used this soap in some time, but there's clearly something more than creaminess to its lather. Potassium hydroxide must be a pretty major proportion of the lye, based on where everything appears in the list, and I'm curious as to whether potassium and stearic acid, besides solubilizing well, have some other particular chemistry as it were in terms of producing voluminous lather.
I am going to make this batch tonight just like the last few except for a revision of the creamy:bubbly ratio. I feel like I'm close to dialing that in, and then it'll be time to mess with the hydroxide ratio. I haven't pondered exactly how much effect a 10% shift in the amount of potassium hydroxide might have, but I'm becoming more curious day by day. The fatty acid proportions clearly are not the only thing that matters, but that's the variable I chose to work with first. At one point, I had in mind that the only thing to do was try to max out the creaminess and bubbliness to the exclusion of everything else, but I'm coming to an understanding that there is something to be said for a ratio of the two factors rather than a maxed-out numerical value, and that leaving something else in the soap may do favors for the durability and lubricity of the lather. Also, clearly, altering the lye ratios has some impact, and how great that impact is remains to be seen.
Last edited by TRBeck
on Sun May 05, 2013 3:46 pm, edited 1 time in total.
Why should we not meet, not always as dyspeptics, to tell our bad dreams, but sometimes as eupeptics, to congratulate each other on the ever-glorious morning? - Henry David Thoreau