Micro batches?

[Johnez]

Hey all, I'm back with another question. I have a few batches to go before I attempt a shave soap, but I'm already brewing it in my head and am slowly gathering ingredients (stearic acid arrived last week, tallow bought 2 days ago...). As some of you know shave soap sometimes lasts quite a while, one of my favorite soap manufacturers offers 1 oz samples that last a whole month!

So the issue is my smallest batch has registered at 25 oz. If I made a "small" 25 oz batch theoretically this would last for TWO years. If I had years of soaping under my belt I would be confident enough to offer it up, but I'm just not quite there yet and I don't want people around me being my guinea pigs (yet....haha).

So my question is this, is there any special considerations in making a tiny (hot process) batches of soap? I'm considering using 8 oz oil, being that I want to test a batch and compare it to another, but honestly I would like to use less (6...maybe 4 oz?) if I could in order to be able to test the max amount of recipes. I'm thinking one would need a super accurate scale at the very least. No stick blending-whisking? Small oven safe pot or other container rather than crock? Smallest crock I've seen is 2 quarts and that seems a bit large.

 

[ResolvableOwl]

Small HP batches are tricky due to water regulation. Small batch = little water, but still a large surface to have evaporation losses. But you can't just put in more water, since initially, too diluted lye will slow down saponification, and later on it complicates solidifcation/unmoulding. And boiling off water is always at the risk to burn the soap batter.

I've done HP batches as small as 3 oz (100 g) oils successfully, but it was a constant babysitting with multiple small water additions, think of cooking risotto. A water bath/simmer pot can be handy, but you can forget about the stick blender. It is possible, yes, but IME not a reliable way to judge how a recipe turns out after full-scale HP.
The final water content, batter consistency, and texture of the resulting soap is more a matter of your skills of stirring and adding water in time, than it depends on initial recipe, let alone its water content.

Also note that stearic acid is not an oil (in the chemical sense) and will react with lye to form solid soap instantly. I have no idea why people are still messing around with soap solidifying into a giant white lump of concrete upon lye addition, and SBing the hell out of it – while it wouldn't need any care at all if done in the right order!
If I had to recommend how to deal with free fatty acids (stearic acid in your case) in a HP recipe, I'd first let the proper oils (triglycerides) saponify without hurry. A few crumbs of FFAs can help to speed up reaching emulsion/trace, but anything above 2% of stearic acid in the initial oils is nothing but self-punishment.
Once reached mashed potato/applesauce phase, stir in the FFAs in 5%ppo portions, wait a few minutes, repeat.

 

[violets2217]

Smallest crock I've seen is 2 quarts and that seems a bit large.

Don't they have little dip size crock pots? I wonder if they get hot enough. I don't HP so I cant help you here. I have made a very small batch of Tooth soap- 8 oz I think- CP and The problem I ran into, I hade to switch containers because it was small enough for my oils, but my stick blender didn't fit in. Good luck!

 

[earlene]

I see those Little Dipper crock pots at resale shops (second-hand stores) fairly often. Here's a link to one. It holds 16 ounces and heats up to 160° - 170°F. I doubt they are all equal in terms of temperature, but that one is hot enough to melt stearic acid.

I used to have a couple because they came with bigger crock pots, but donated them as I never had a need for them. Since making soap, I wondered if maybe they'd have come in handy, but in spite of seeing them quite often in thrift shops, I've never really been tempted to pick one up.

I used to have a dual compartment crockpot similar to this one:


You know, what you can do to still use a normal-ish or smaller crockpot, is something along this line, but not with glass jars, rather a good quality stainless steel bowl that won't fall over in the heated water surrounding it:

 

[Johnez]

Small HP batches are tricky due to water regulation. Small batch = little water, but still a large surface to have evaporation losses. But you can't just put in more water, since initially, too diluted lye will slow down saponification, and later on it complicates solidifcation/unmoulding. And boiling off water is always at the risk to burn the soap batter.

I've done HP batches as small as 3 oz (100 g) oils successfully, but it was a constant babysitting with multiple small water additions, think of cooking risotto. A water bath/simmer pot can be handy, but you can forget about the stick blender. It is possible, yes, but IME not a reliable way to judge how a recipe turns out after full-scale HP.
The final water content, batter consistency, and texture of the resulting soap is more a matter of your skills of stirring and adding water in time, than it depends on initial recipe, let alone its water content.

Also note that stearic acid is not an oil (in the chemical sense) and will react with lye to form solid soap instantly. I have no idea why people are still messing around with soap solidifying into a giant white lump of concrete upon lye addition, and SBing the hell out of it – while it wouldn't need any care at all if done in the right order!
If I had to recommend how to deal with free fatty acids (stearic acid in your case) in a HP recipe, I'd first let the proper oils (triglycerides) saponify without hurry. A few crumbs of FFAs can help to speed up reaching emulsion/trace, but anything above 2% of stearic acid in the initial oils is nothing but self-punishment.
Once reached mashed potato/applesauce phase, stir in the FFAs in 5%ppo portions, wait a few minutes, repeat.

This is a fascinating take on some of my unasked, but very much needed answered questions. Thanks for the feedback! I've never cooked risotto, but I think I get the picture....a challenge for sure.

With regards to stearic acid, if I'm reading correctly one would keep it in the calculations for lye just like a base oil, and simply add it to be the last to be saponified, correct? Basically NOT a superfat is what I'm confirming, as I'd rather try to use a butter as a SF. Your advice on the order of addition is a mighty help already as I've seen many a post detailing the crumbles that result from stearic acid.

 

[Johnez]

Don't they have little dip size crock pots? I wonder if they get hot enough. I don't HP so I cant help you here. I have made a very small batch of Tooth soap- 8 oz I think- CP and The problem I ran into, I hade to switch containers because it was small enough for my oils, but my stick blender didn't fit in. Good luck!

Didn't even think of these, awesome!

I see those Little Dipper crock pots at resale shops (second-hand stores) fairly often. Here's a link to one. It holds 16 ounces and heats up to 160° - 170°F. I doubt they are all equal in terms of temperature, but that one is hot enough to melt stearic acid.

I used to have a couple because they came with bigger crock pots, but donated them as I never had a need for them. Since making soap, I wondered if maybe they'd have come in handy, but in spite of seeing them quite often in thrift shops, I've never really been tempted to pick one up.

I used to have a dual compartment crockpot similar to this one:
View attachment 56380

You know, what you can do to still use a normal-ish or smaller crockpot, is something along this line, but not with glass jars, rather a good quality stainless steel bowl that won't fall over in the heated water surrounding it:
View attachment 56381

Gotta keep my eye out for these. The "double boiler" method is a nice workaround that can turn any bigger crockpot into a small one. I didn't even think about that, was wondering if I could put a small pot into a big pot but the logistics of stabilizing it seemed not that easy. Converting the crockpot into a double boiler makes MUCH more sense lol, I think this may be the way to go. Thanks for sharing, feels much more doable.

 

[ResolvableOwl]

The tricky thing about stearic acid is that it behaves from many practical points of view like an oil/hard fat (it melts and mixes with other oils, has similar lye consumption numbers, and is included in lye calculators). When added in soaps, amounts are usually in the low single-digit percentage regions where the actual protocol doesn't matter that much. But shave soap (AFAIK, I never made one) is different.

I don't know your recipe. In case it has said butter explicitly as late superfat, and treats stearic acid as a base oil, the only modification you are doing is adding the stearic acid not in the beginning, but during the process, i. e. you start cooking a quite lye-heavy batter and approach the lye break-even point from below step by step, with FFA additions in between.

I've never cooked risotto

I can't really blame you for neglecting risotto. Not me, with an unopened bag of risotto rice (best before date in 2018) . But if you're anything into cuisine, try it! (And if not, you're possibly wrong at HP soapmaking as well.)

 

[Johnez]

@ResolvableOwl , thanks-that is the process I'll stick with for now. I'm going to eventually attempt the famous @songwind (here's a bat signal for a long lost poster!) recipe which calls for an astounding 52% stearic acid. Being there's not much trouble reported with that recipe, perhaps the KOH or the HP method lets stearic acid behave better. Small issue tho-I've only NaOH to experiment with right now so it might be a whole 'nother game.

Regarding risotto, oh that's "aged" risotto now, even better lol! I'll stick it on my to do list. My dusty chipotle chiles might get mad tho if I take on any more culinary projects before perfecting that salsa.

***

Now to switch gears because my brain immediately reaches for the next crazy thing being I'm a complete novice here but here's the next question-I notice a lot of you all prebatch lye and oils....what about saponifying oils into prebatched "proto-soaps" to be mixed in later in the crock to be formed into the final product (scented and all).

A sort of rebatching similar to how commercial soaps combine all the "-ates" like sodium tallowate and sodium cocoate, etc. Is this feasible idea? My hopeful self envisions having my "-ates" at the ready and simply mixing them up in various combos in new final forms adding scent or superfat or whatever at the rebatch.

Anyway, I figure this might simplify the process being that I could saponify fats by the pound ahead of time and simply portion off a few oz of each to melt into 4 oz or heck maybe even 2 oz pucks. Does any of this make sense?

 

[Tara_H]

Now to switch gears because my brain immediately reaches for the next crazy thing being I'm a complete novice here but here's the next question-I notice a lot of you all prebatch lye and oils....what about saponifying oils into prebatched "proto-soaps" to be mixed in later in the crock to be formed into the final product (scented and all).

A sort of rebatching similar to how commercial soaps combine all the "-ates" like sodium tallowate and sodium cocoate, etc. Is this feasible idea? My hopeful self envisions having my "-ates" at the ready and simply mixing them up in various combos in new final forms adding scent or superfat or whatever at the rebatch.

Anyway, I figure this might simplify the process being that I could saponify fats by the pound ahead of time and simply portion off a few oz of each to melt into 4 oz or heck maybe even 2 oz pucks. Does any of this make sense?

I think that's what @ResolvableOwl is proposing in the thread about superfatting soap dough - personally it's kind of the opposite to what I would want to do since I very much enjoy the process of CP soap making, but since you seem to be a glutton for punishment and like HP (for some unknown reason ) maybe you'd enjoy doing things that way.

I believe it's easy enough to add scent to a rebatch, but colouring may be harder. I ended up rebatching a HP soap a little while back and I put it in my stand mixer with the soft blade to try to blend the colours together well. I would not fancy trying to do that by hand unless I was in training for some sort of strongman competition! As you can see it still didn't end up with the colour fully mixed through, although better than the meat-looking soap it was to start with!

 

[ResolvableOwl]

I had to look up that Songwind recipe. He's using KOH, which makes things a lot easier because potassium soaps are much more reluctant to solidification. I also see that you have already been tortured by the soy wax aficionados to replace free stearic acid by stearin triglyceride, which is definitely a clever idea, though a bit untimely now that your order of stearic acid has arrived.

Regarding soap masterbatches and “-ates”: that's a complex topic. For liquid soaps it sounds like a non-issue: just stir together whatever you want to end up with. But bar soap is not only about chemistry, but a large part is texture. It's just impossible to replicate the texture and longevity of a CP soap with rebatching, neither can it keep up with a properly made HP bar. (And don't listen to @Tara_H and her smear campaign against HP !)
There is some degree of freedom for “designer soaps” (one of which is said soap dough thread), but only to a limited degree. An sodium safflowerate intermediate (what a monstrosity of a word!) is imaginable, bit I'm having a hard time to imagine how to prepare sodium salts of soy wax to somehow knead it in there.
At the same time I'm fully d'accord with @Tara_H that blending oils and soaping from scratch is so much more fun and satisfying than rebatching, that I never would want to give up on it, for the sake of additional and “bureaucratic” composition work afterwards.

By the way, are you aware of the composition of what was sold as “stearic acid” to you? Unfortunately, this might either be pure stearic acid (C18:0), or a blend of stearic (C18:0) and palmitic (C16:0) acid, which behaves identical in most use cases, but has a higher lye consumption. Does the shop/packaging/datasheet give you pointers? like “triple pressed”, origin Indonesia/Malaysia or temperate climate, INCI, saponification/acid value, melting point

 

[Johnez]

@ResolvableOwl

Ah yes, hehe, I was tempted to go with soy, but decided against it. Researching that ultimately led me to some interesting possibilities tho.

I got the stearic acid from "From Nature With Love" (can't post link) which is soy derived, and states INCI: Stearic Acid. Their spec sheet is interesting:

Fatty Acid Profile
C14:0 Myristic: ≤ 1.5%
C16:0 Palmitic: 45 - 56%
C18:0 Stearic: 40 - 55%
> C18:0 ≤ 1.0%

Hmmm. I would have figured 100% stearic acid by the uh...description of stearic acid. Hydrogenated soy appears to have a higher composition of stearic acid in SoapCalc at 99. What in the world? Drat, maybe I shoulda stuck with the soy!

They do list this however:
Saponification Value (mg KOH/g oil): 206 - 213
SAP Multiplier for NaOH: 0.15
SAP Multiplier for KOH: 0.21

Just checked with SoapCalc and they list these SAP numbers (pretty close)-
NaOH: .143
KOH: .2

@Tara_H, oh boy I will have to investigate this soap dough idea, I guess the idea completely flew over my head. Regarding mixing, oh that sounds harder than I thought, I guess a potato ricer is a nonstarter?

Ok guys apologies for the brief reply, wow there's some meaty reading material (and soaps haha!) but I've got to get a bit of shuteye. Thanks a ton!

 

[Becky1024]

You already have lots of good information here, and I'll add my two cents. I've made shave soaps regularly for the past several years, and the high stearic acid content you need to get a good shave soap makes it behave quite differently than a "normal" hp soap. The melting point of stearic acid is quite high compared to solid fats - about 156F / 70C. So you will need to soap quite hot and be prepared to work quick. I normally start with my mixture of oils & stearic acid in the 135 - 150 range and my lye water in the same range. At that temperature it kind of HP's itself!

Forget about stick blending. With the high stearic it will go to soap on a rope quick. All you need is to whisk or rapidly stir to keep it emulsified.

I like the ideas of a small crockpot or using a double boiler for your test. Another idea - and I have not tried this - is to HP it in a coffee mug or insulated cup. Since you are starting hot the mug may be enough to keep it warm.

I find a short HP time (about 20 minutes) works best with my recipe. If I let it HP too long my bars are crumbly. So that is something you may want to test with your recipes so you don't ruin a batch.

 

[ResolvableOwl]

Lyecalc.com lists “Commercial Stearic Acid (Triple-Pressed Stearic/Palmitic Blend)” with P:S=55:45 similar to your spec sheet. That calculator has its rough edges (unprecise SAP values), better recheck with another one, and “blend” your own mix by entering numbers for pure palmitic and stearic acid.

I've read somewhere that “stearic acid” can denote either of “the one saturated fatty acid with precisely 18 carbon atoms” (like chemists), or “the fatty acids from the stearin fraction of palm oil, and equivalent sources” (cosmetics-grade level of nitpicking). You're in luck that your source is that chatty about its properties! It is most likely the saturated fats sequestered from (unhydrogenated) soybean oil (P:S=11:5 per soapmakingfriend), with some of the palmitic acid removed (or a different cultivar/climate…).
If all unsaturated FAs (oleic, linole(n)ic) of soybean oil were hydrogenated to stearic acid (like for hard soy wax), one would end up at about P:S=11:88. We can only guess about the economical reasoning of the manufacturers to avoid hydrogenation; but it's not important anyway, since you have these numbers! Easiest for you is to divide the “stearic acid” of your recipe in half, and enter these two numbers as separate stearic and palmitic acids into the soap calculator of your choice.

Or go to
http://www.soapcalc.net/calc/OilList.aspand pick out a random oil that has your desired SAP, and put this into the recipe instead. You're in luck to have reasonably precise SAP values supplied by the manufacturer!


ad @Becky1024's pointer with melting temperature: pure stearic acid melts at 69.3°C, pure palmitic acid at 62.9°C, but blends of both can melt as low as 52.3°C. You can confirm that your acids are a blend by just putting a thermometer into the flakes as soon as they start melting.

 

[Johnez]

Lyecalc.com lists “Commercial Stearic Acid (Triple-Pressed Stearic/Palmitic Blend)” with P:S=55:45 similar to your spec sheet. That calculator has its rough edges (unprecise SAP values), better recheck with another one, and “blend” your own mix by entering numbers for pure palmitic and stearic acid.

I've read somewhere that “stearic acid” can denote either of “the one saturated fatty acid with precisely 18 carbon atoms” (like chemists), or “the fatty acids from the stearin fraction of palm oil, and equivalent sources” (cosmetics-grade level of nitpicking). You're in luck that your source is that chatty about its properties! It is most likely the saturated fats sequestered from (unhydrogenated) soybean oil (P:S=11:5 per soapmakingfriend), with some of the palmitic acid removed (or a different cultivar/climate…).
If all unsaturated FAs (oleic, linole(n)ic) of soybean oil were hydrogenated to stearic acid (like for hard soy wax), one would end up at about P:S=11:88. We can only guess about the economical reasoning of the manufacturers to avoid hydrogenation; but it's not important anyway, since you have these numbers! Easiest for you is to divide the “stearic acid” of your recipe in half, and enter these two numbers as separate stearic and palmitic acids into the soap calculator of your choice.

Or go to
http://www.soapcalc.net/calc/OilList.aspand pick out a random oil that has your desired SAP, and put this into the recipe instead. You're in luck to have reasonably precise SAP values supplied by the manufacturer!


ad @Becky1024's pointer with melting temperature: pure stearic acid melts at 69.3°C, pure palmitic acid at 62.9°C, but blends of both can melt as low as 52.3°C. You can confirm that your acids are a blend by just putting a thermometer into the flakes as soon as they start melting.

Wow, thanks on so many levels. Firstly for making me aware of my "stearic acid" possibly having different SAP values, and secondly for pointing out the oil sort feature on SoapCalc. What a useful tool. "SoapQuick Conventional" is quite close on both numbers (.212, .151). Is there a reason to be worried if I can only get it to the thousandths (.xx)?

So much to digest, again thanks for the responses all, this would have been an exhausting slog if I had to middle through this all on my own.

 

[Johnez]

You already have lots of good information here, and I'll add my two cents. I've made shave soaps regularly for the past several years, and the high stearic acid content you need to get a good shave soap makes it behave quite differently than a "normal" hp soap. The melting point of stearic acid is quite high compared to solid fats - about 156F / 70C. So you will need to soap quite hot and be prepared to work quick. I normally start with my mixture of oils & stearic acid in the 135 - 150 range and my lye water in the same range. At that temperature it kind of HP's itself!

Forget about stick blending. With the high stearic it will go to soap on a rope quick. All you need is to whisk or rapidly stir to keep it emulsified.

I had a feeling about the stick blender not working out. With an amount as small as I'm thinking about trying might not be an issue tho simply whisking it.

I like the ideas of a small crockpot or using a double boiler for your test. Another idea - and I have not tried this - is to HP it in a coffee mug or insulated cup. Since you are starting hot the mug may be enough to keep it warm.

I find a short HP time (about 20 minutes) works best with my recipe. If I let it HP too long my bars are crumbly. So that is something you may want to test with your recipes so you don't ruin a batch.

I've got my eye on a tiny 7 oz stainless steel container on Amazon, this might get interesting heh. Thanks for the feedback.

 

[Corsara]

I've done a 12 oz batch of the @songwind recipe, and that stuff is amazing! I did dual lye, but in general, the two step saponification process suggested by @DeeAnna made it a breeze, even for smaller batches. I used a stainless steel bowl over a pot of water, so definitely don't need a Crockpot.

Love the info on this thread by the way!

 

[ResolvableOwl]

Is there a reason to be worried if I can only get it to the thousandths (.xx)?

In your case, no. They have literally written “Saponification Value (mg KOH/g oil): 206 - 213”, so they only specify the K-SAP to be between 206 and 213 (equivalent Na-SAP range 147–152). There is no point for you to pretend a level of precision that never had existed anyway.

I did dual lye, but in general, the two step saponification process suggested by @DeeAnna made it a breeze, even for smaller batches.

Look what's all buried in old threads of this forum! Had I read through that thread more thoroughly, I'd realised by myself that my above suggestion of late addition of stearic acid is, once again, reinventing the wheel…

By the way, the word “saponification” is used in two meanings here. Literally, it means “making soap”, i. e. a chemical reaction that has soap (in this case sodium stearate) as its product. But in chemical language, the same word denotes “cleavage of ester bonds by lye”. Stearic acid has no ester bonds (it is a free fatty acid, not an ester/proper oil/triglyceride molecule), so from this perspective it cannot “saponify” at all, even in a reaction that produces sodium stearate. Chemists call this reaction “acid-base neutralisation”.
Being nitpicky, it's not a “two-step saponification” if the second step is stearic acid, but a “[lye-heavy] saponification [of the proper oils], followed by a neutralisation of excess lye with free fatty acids”. But “two-step saponification” sounds more handy than that.
I'm working this difference out since ester saponification is slow (minutes to days), but acid-base neutralisation is fast (milliseconds), even though the products might be the same. It makes a huge practical difference which one to carry out at which time.

I had a feeling about the stick blender not working out.

It is at times painful to merely watch how people get into trouble when they add stearic acid too early! That poor stick blender only made things worse.

 

[Johnez]

In your case, no. They have literally written “Saponification Value (mg KOH/g oil): 206 - 213”, so they only specify the K-SAP to be between 206 and 213 (equivalent Na-SAP range 147–152). There is no point for you to pretend a level of precision that never had existed anyway.


Look what's all buried in old threads of this forum! Had I read through that thread more thoroughly, I'd realised by myself that my above suggestion of late addition of stearic acid is, once again, reinventing the wheel…

By the way, the word “saponification” is used in two meanings here. Literally, it means “making soap”, i. e. a chemical reaction that has soap (in this case sodium stearate) as its product. But in chemical language, the same word denotes “cleavage of ester bonds by lye”. Stearic acid has no ester bonds (it is a free fatty acid, not an ester/proper oil/triglyceride molecule), so from this perspective it cannot “saponify” at all, even in a reaction that produces sodium stearate. Chemists call this reaction “acid-base neutralisation”.
Being nitpicky, it's not a “two-step saponification” if the second step is stearic acid, but a “[lye-heavy] saponification [of the proper oils], followed by a neutralisation of excess lye with free fatty acids”. But “two-step saponification” sounds more handy than that.
I'm working this difference out since ester saponification is slow (minutes to days), but acid-base neutralisation is fast (milliseconds), even though the products might be the same. It makes a huge practical difference which one to carry out at which time.


It is at times painful to merely watch how people get into trouble when they add stearic acid too early! That poor stick blender only made things worse.

Ain't nothing new under the sun RO, but a technique such as the "2 step saponification" bears repeating. Stuff like this gets lost in the ether otherwise, I'm glad you brought it up.

Regarding 2 step saponification, I actually went down a rabbit hole while researching for my "-ates" mixing idea and found there is another one that industrial soap makers use that treats fats with steam hydrolysis, and then the lye. Interesting stuff comes up when out on a wild goose chase haha. Also found out old paintings also go through saponification, unfortunately an undesirable kind that eventually degrades a masterpiece. Here I am off on a tangent again in my own thread heh.

 

[ResolvableOwl]

there is another one that industrial soap makers use that treats fats with steam hydrolysis, and then the lye.

It's unfortunate that (acidic/steam) hydrolysis is effectively impossible on smaller than industrial scale, since it needs a reactor with high temperature and vigorous mechanical mixing. In principle it's cleaner, more controllable and flexible than lye saponification.
To some degree one can imitate that FFA building blocks principle of industry. Add excess acid (acetic, citric, sulfuric, hydrochloric…) to an artisanal soap → FFAs (stearic, oleic, lauric, ricinoleic acids…) precipitate, and you can sequester them, blend them to your needs, and neutralise (“saponify”) them with lye afterwards – with all the downsides of handling FFAs, and not very efficient overall (you'll need double the amount of lye), but the ultimate rebatch.

A “green chemistry/bio-engineering” route that might be in reach from a kitchen level is enzymatic hydrolysis: using lipase (from soybean sprouts, e. g.) to break down oils into glycerol and FFAs at much milder conditions than with steam hydrolysis.

an undesirable kind that eventually degrades a masterpiece.

Slight abuse of context, but I couldn't resist!

 

[Johnez]

Slight abuse of context, but I couldn't resist!

Another fan of high culture I see.