Dr. Kevin Dunn Saturday P.M. Presentation

Dr. Kevin Dunn, Professor of Chemistry at Hampden-Sydney College and author of “Scientific Soaping” and “Caveman Chemistry”, presents the “Secret Life of Soap”, in which we learn the chemistry involved in the conversion of oil and lye into soap. His presentation includes lessons on what actually occurs during saponification at the molecular level, and answers questions that many soapers don’t even know they have. Dr. Dunn dispels myths and wives tales and gives you permission to experiment with other tactics. Temperature, water volume and gel phase are scientifically analyzed, and an important distinction is made about why nerds and cheerleaders don’t sit together in the lunchroom. If you never loved science in school, Dr. Dunn will change your perspective and make learning soap chemistry an adventure.

 KD -  So, when Derek asked me to talk, what do you want me to talk about.  Because I have lots of things I can talk about and he said, well, I saw you do this thing about superfatting and why don’t you do that and I said okay.  And then I completely forgot.  And so when I went to get this presentation ready, I just said well, they’ll probably like the Secret Life of Soap.  So I put that together and I only learned about 20 minutes ago that the title wasn’t what I thought it was.  So, the presentation on superfatting and lye discounting is Chapter 20 in the book, so if you’re curious about that you can look at that.
Now I’m going to pick up where I left off this morning.  Also, Derek said I had a half an hour for each presentation and I see I’ve got an hour on the schedule, so I feel a little more relaxed and comfortable now.  If anybody has questions from this morning, I know it was a lot of stuff to throw, especially at people that don’t know one end of a molecule from another.  So does anybody have any questions from this morning?
Okay, to pick up where we left off, we talked about phases of soap, we talked about a particular phase called neat soap, what we know as gel phase, the stuff that looks like Vaseline, and the temperature at which it appears depends on the water content in the soap.  That was summarized in this diagram.  If I’m in a low water domain, if I’ve got only a little water in the soap, I’ve got to get to a very high temperature before the gel phase is going to appear.  If I’m at medium water, I only have to get to maybe 170, and if I’m at high water, I only need to get to about 140, maybe 144, before I see the gel phase.  
And so, those numbers are going to be important for us to sort of remember.  I’m just going to refer to them as cold, warm and hot, but we’ll see how that plays out in more detail.
This is a graph, let me describe what this is.  This is a student who took a soap, made a particular high water soap, and he started it out at 40⁰C which is like 100⁰F, and then he measured the temperature of that soap every 10 minutes for 4 hours.  And then he plotted that and this is what we see. What happens to the temperature of this soap over 200 minutes, and you see it goes up a little bit and then it gradually comes back down again.  If we do a medium water soap, how is that different from the high water soap?  It gets hotter and it stays hotter longer.  If I go to a low water soap, oh wow, that’s getting really hot and it rises up to well, about 80⁰C, like about 180⁰F, that’s really quite hot.  And the only difference between these soaps, they all started at the same temperature, the only difference is, one of them had not a lot of water, a medium amount of water, or a high amount of water.  
So you can control many things in the soap process.  You can control the amount of water that you put in and you can also control the starting temperature of your materials.  Let me ask you a question, does the oil and lye have to be at the same temperature when you mix them together?  Yes?  No?    KD – It doesn’t matter.  So let’s think about it.  How much oil are we using?  In the formula I made, let’s say 1000g of oil.  And how much lye is going in?  288 in our formula.  Well, you know what, whatever temperature the lye is at, it’s going to quickly, the lye and the oil are going to come to the same temperature.  I’m not saying that it won’t make any difference, but it won’t make much difference.  You certainly don’t have to wait around until your lye and your oil are exactly the right temperature.  We always use room temperature lye, and of course, room temperature changes from season to season.  It doesn’t make that much difference, it’s the oil temperature that is the 800 pound gorilla in the room.  We always use room temperature lye, how come?  It’s easy.  We can just keep jugs of the stuff lying around and then we’re never waiting for it to cool, we’re certainly never trying to heat it up.  
We bring oil to the temperature that we want it to be, then we add the lye, and we have a lot more control over the ultimate temperature by controlling the water than we do controlling the lye temperature.
There’s another way to slice this.  Now this is different because it’s controlling something different.  These are all low water soaps.  The difference between these is we started one cold, we started one warm, and we started one hot.  And if you look at these, what’s the story that you see?  The cold doesn’t get as hot, so this makes perfect sense.  The hot one gets the hottest, and the medium gets to a medium temperature.  And the cold one rises the lowest.    KD - The hot one, so they fall down roughly parallel to one another, right?  So let me ask you, for this low water soap, how hot did it need to be to reach a gel phase?  And for that, you’re going to have to remember back to the graph that I started with.   KD – No, for a low water soap.  It had to be like 200, it had to be really, really hot.  Is it getting hot enough?  It had to be over 100⁰C, it’s close but it’s not, certainly it has to be, it has to start out really hot if it has any chance of reaching the gel phase.  And in fact, none of these three soaps gelled.  They all reached trace, they all got poured into the mold, they became solid, and they just stayed solid the whole time.  They never reached any kind of a gel phase.
  KD – Right, and that’s what we’re controlling, we’re controlling the initial temperature, and we’re following what happens to the temperature depending on the water content and the initial temperature that we start at.
  KD – So remember, I might have to back up for that.  Remember what cold means, in this presentation, cold means 100⁰F.  Okay, so typically that’s where a cold process soap maker might be making soap.  If you go a little bit warmer, you’re talking 140⁰, and if you’re talking hot, you might be at 160, 170.  So, when we’re talking about cold, warm, and hot, I didn’t want to keep talking about temperatures, I wanted some kind of a shorthand for that.  Cold means 104⁰F, warm means 140, and hot means 176.    KD – For this one, for this low water soap, remember… I’ve got to get, look how high up that curve is.  It’s way above 100, way above 200, it’s above the boiling point of water certainly.  So, I’ve got to have it boiling hot before it’s going to reach a gel phase, and in that case, what’s going to happen?  The water’s probably going to boil, so I’ve got other problems that are going to happen.  So, for this low water soap, my prediction is I’m never going to reach gel phase, and does that make it bad soap?  It’s perfectly good soap.  But we’re going to discuss, what’s the difference between the soap that gelled and the soap that didn’t gel?
Alright, so that’s the low water soap.  This is Aq₇₂, this is at the low end but it’s not quite to medium.  Okay, so it’s in between the low water soap and the medium water soap.  Again, I start out at 40, 60, and 70⁰, and again, the one that started hot gets hotter, the one that started cold stays colder, but they all kind of rise and fall together; and I put here the line, there’s the line for an Aq₇₂ soap.  The line between a solid soap and our gel phase.  Did any of these three soaps gel?  No.  And visually, when the student went to look at them, none of these three soaps reached gel phase.  
Here’s a medium water soap.  And again, we start out, we’ve got a cold, a warm and a hot soap.  And you can see what happens, and this is really, really cool.  So the hot one went up in temperature and then it reached that gel phase, and look what happened.  It started to take off.  It got even hotter, something changed when it reached the gel phase and that accelerated the reaction and it went very quickly to a higher temperature.  And visually, of these three soaps, the hot one is the only one that reached gel phase.
Okay, here is Aq₂₁₆.  This is at the high end but not quite to a high water soap.  This is an intermediate one and you can see both the warm one and the hot one reached gel phase, but the cold one didn’t. 
And then here’s our high water soap.  This is the one at the highest water content.  You can see the hottest two of them, and you see the same behavior, temperature goes up but as soon as it reaches gel phase, the temperature really starts to climb. So the formation of the gel phase accelerates the saponification process, and we get to a higher temperature.  Both of the top two gelled, and the one on the bottom didn’t.
So I’m now going to go to the microscopy, and this stuff that we just talked about is in the book, it’s in a chapter called Time and Temperature, but the microscopy is new.  It was done after the book came out.  I want to give particular credit to Avery Moncure, who did this work.  He had a whole two semesters to work with me.  He had an honors project, and in the microscopy part of it, he developed a procedure by which he would make soap, put it in a microscope slide and look at it under the microscope as the soap was forming.  He had to learn all of the computer programming to run the microscope and the camera, and to take pictures.  So I’m going to show you some video clips later, and those video clips came from him looking at soap under a microscope, snapping a still photo every ten minutes for 8 hours and then combining all those still figures into a video clip; and we had a lot of back and forth, with him saying no, it can’t be done, it can’t be done.  And I said yes, it can be done; I don’t know how to do, that’s your job.  But, I know it can be done.  And he’d come back with something and he’d say well, how about this.  And I’d say, Avery, that’s the stupid way, I don’t know what the smart way is, I just know this isn’t it.  So, he worked, he’s a really smart guy who worked very hard to get what we’re going to see, the culmination of his work is four 2-minute video clips, and as you’re watching them, you can imagine this poor guy sitting in the lab all night long, with a microscope.  So I have to really call him out on that.
This is what a low water soap looks like at 200x magnification.  And you can see it’s got, it’s not completely clear.  When you mix up soap, some of you are going to see this for the first time this afternoon; but those of you who’ve made soap, what does oil look like?  Is it translucent or transparent?  It’s important.  It’s transparent.  Can you see through it?  A bottle of Wesson Oil, can you see through it?  And I want to draw the distinction between having a color, and being transparent.  Oil, let’s talk about palm oil, is it translucent, is it transparent, or is it opaque?  It’s opaque.  Now my question is, why is it opaque?  You can’t see through it so I’m going to teach you something about light.  Why can’t you see through it?  And why can’t light get through it?  It’s reflected, why is it reflected?  So the questions never end.  I can keep asking questions all day long.  When a light ray goes through something, it will go through unless it bounces off something.  In order to bounce off something, the something that it bounces off of has to be about the same size as the wave length of the light.  Okay.  So, in your solid palm oil, you’ve got palm oil crystals.  The palm oil crystals are about the same size as the wave length of visible light.  So a light wave going into palm oil hits that crystal and it bounces off.  So it doesn’t appear black, it appears white, because it’s the light that’s coming in being bounced off in a different direction than what it was traveling originally.  
When you melt palm oil, what happens?  It becomes translucent first, and then transparent.  You can see through it, right?  If I were to hold it up, I could actually see, you’d be all warped and distorted, some of you would be fat and some would be skinny and it would depend on which way I was looking; but I can see through it.  It’s transparent, it’s transparent because the light comes in and it doesn’t find anything that’s the same size as the wavelength of light.  How big are the things, they’re oil molecules.  How big are oil molecules?  Compared to light wavelengths, they’re tiny.  The molecules are tiny so they can’t, the light ray doesn’t bounce off of them, if it doesn’t bounce off it goes straight through; and that’s why, when I look through it, I don’t see the light that’s coming in from the side, I see the light that bounced off your face and came straight through the material.  
So, the oil is transparent.  How about the lye?  Solid sodium hydroxide in the bottle over there.  It’s opaque, why is it opaque?  Because there are crystals, why? Because the crystals are larger than a molecule, in other words, the crystals are about the same size as the wavelength of light, so instead of light passing through, light bounces off.  It’s reflected at a different angle.
Now let’s dissolve that lye, let’s dissolve that caustic soda in water to make lye, and what does it look like?  It’s transparent again.  Why is it transparent?  Because they dissolved.  It went from a bunch of sodium hydroxide molecules all packed together, to sodium hydroxide molecules now dispersed in water.  Remember we saw a sodium ion surrounded by its little harem of water molecules, and the hydroxide molecule is also surrounded by its little harem of water molecules.  What we’re seeing is, these are individual molecules that are too small for light to bounce off of them.  
Now you took the transparent oil and you mixed it in the transparent lye, and what does it look like now.  It’s not transparent anymore.  Why isn’t it transparent?  It made something.  Now, you don’t know from looking at it what it is, but what you do know is, whatever formed when you mixed them together, is bigger than a molecule.  Bigger than a molecule.  And now we’re looking at it under the microscope at 200x magnification.  And what do you see there?  You don’t see something that’s uniformly flat.  If it were just oil, you would see something that’s uniformly yellow.  If it were just lye, you’d see something that was uniformly transparent.  This is low water soap that’s just been mixed up and put on the microscope and what do we see?  It’s like little worms.  There are little dark places and little light places, and I’m thinking to myself, what is that?  When you mix oil and water, essentially, they gotta break up into something, into droplets or something.  And in this region, we’re looking at little channels of intermingling oil and lye.  How big are they?  They are about the same size as the wavelength of light.  Molecules are much smaller.  So these are fairly large structures compared to the wavelength of light.  So light coming in doesn’t just go through them, light coming in bounces off of them and you don’t see that they’re transparent.  
If we change the water content, here’s a medium water soap.  What do you see?  You can probably recognize something going on now.  What do you think this is?  It’s not, this is like 45 seconds after mixing, there’s no soap here yet.  If you got a little circle and a little circle and a little circle and a little circle, what do you think that is?  Okay, it’s one of two things, and we don’t know what it is.  Is it a little droplet of lye surrounded by oil, or is it a little droplet of oil surrounded by lye; or are both of them present?  Now, I don’t know.  So how many of you know?  How many of you if asked, would give an answer?  This is the tragedy of soap making, is if you go online, everyone has an answer.  People can’t help themselves.  They will say, oh, this is… and they’ll give you an explanation.  This is obviously droplets of lye surrounded by oil because blah, blah, blah, blah, they’ll give an explanation.  Or the other way around.  So at this moment, we don’t know.  
How are we going to decide whether it’s a droplet of oil in lye or a droplet of lye in oil?  And the solution we came up with, you know there are different kinds of pigments, there are oil soluble pigments and there are water soluble pigments.  So we used both and looked at it under the microscope, and when we used water soluble pigments, all the color was here in the droplets.  When we used oil soluble pigments, all the color was outside the droplets.  So we concluded that these are droplets of lye that are suspended in the oil.
That’s a medium water soap, same magnification.    KD – Well we’ve already seen that’s not the case in at least one case, look at that.  I don’t see any droplets at all here.  Is there a regime in which you might get droplets of oil surrounded by lye?  I don’t know, we’ve never seen that.  If you said , “What wouldn’t surprise you?”, it wouldn’t surprise me if you added 1g of oil to 100g of lye, it wouldn’t surprise me to see oil droplets surrounded by lye.    KD – You mean water compared to milk, or compared to some other thing?  I don’t know, I really don’t know.  That would be really interesting to look at that under the microscope.  But it’s not something I can tell you.  
Okay, so low water soap, we see intermingling channels; medium water soap we’ve got droplets of lye.  And a high water soap, once again we’ve got here the little droplets and the same result.  If we ask, what are those little droplets, they’re little droplets of lye, suspended in oil.  This is just microscopy, and if I were to show you a micrograph of soap aging under the microscope, it would be really boring.  You would hardly see, you would hardly notice any difference.  
What we’ve done is to look at it under polarized light, and polarized light gives us a lot of information about the structure.  And so to talk about polarized light, anybody have polaroid sunglasses?  Okay, so light can be polarized when the waves are all moving in a plane, so a polaroid lens allows light to go through that is vibrating this way, but doesn’t allow it to go through if it’s vibrating that way.  Let’s imagine your glasses are polarized and I’m going to break them in half.  I now have two polaroid lenses.  And you can get yourself a cheap pair of sunglasses, make sure they’re polaroid sunglasses.  And I’m going to take those two lenses and I’m going to put one in front of the other.  I should have brought some polaroid sunglasses.  But, you’re going to see light, and it’s going to be transparent because the light is going this way, and it goes through the first lens, and it also gets through the second lens.  Now let’s take that second lens and we’re going to rotate it 90⁰, and this is really fun if you’ve never done it.  You’ll see transparent, less transparent, less, uh-oh, now it’s black.  No light can get through.  Because only this light gets through the first lens and only that light gets through the second lens.  
Now this is really cool, and you gotta do it.  I’m sorry I didn’t bring a cheap pair of sunglasses to break.  Get yourself a cheap pair of polaroids, break them in half, and take a piece and go across one of the lenses.  Take the second lens and put it in front and turn it 90⁰ and you’ll see it turns black, except where the soap was.  Because the soap, the soap crystal, changes the plane of polarization of the light.  So all the light was going this way, it hits the soap, and now it’s going this way, not this way; and some of that gets through the second lens.  And by changing the relative angles of those polarizing filters, you can get some really, really pretty pictures.  Soap is beautiful under polarized light.  I think you’re going to be happy.
Under regular light, it’s not so interesting. But, I’m going to back up.  Remember what I said about this structure.  Light going this way is different from light going that way; and so a structure like this is going to appear different under polarized light than either oil does where the molecules are all random.  Or lye, where the molecules are all random.  We’re going to be able to see, are there large scale crystals in the soap by looking at it under polarized light. 
If the soap crystals are small, what’s going to happen?  Light comes up on something small, about the same size as a light wave.  It’s going to bounce off.  So as I’m looking at the microscope, light coming up through the soap, if it hits a small soap crystal, it’s going to bounce off, it’s going to appear black.  But if I hit a structure like this, a crystalline structure that’s large compared to the wavelength of the light, it’s going to appear colored under polarized light. We’re going to be able to see that.
So the lye and the oil is going to appear uniformly purple under a polarized light.  It’s going to appear transparent and it’s going to have a purple color because it doesn’t matter to oil which direction the oil is coming in because the molecules are all in random orientation.  Only if there’s a large crystal will you see colors and if the soap crystals are small, the light’s going to bounce off and it’s going to appear black.  We’re going to see that in time.  
So these are four soap samples.  I’ve got a high water cold sample; a high water warm sample; a medium water cold sample; and a medium water warm sample.  And you can see they look very similar.  They’re uniformly purple, that means the stuff in them is oil and lye.  There are no large scale structures for light to bounce off of, and we see the droplet structures that we saw in the earlier micrographs.  
That’s ten minutes later, let’s go back; okay, yeah, ten minutes later, and what’s changed?  Not very much really.
This is now at sixty minutes and we see one of the four samples has changed.  These colors, the red and the green and yellow, come from light coming through the first polarizing filter, hitting the soap, changing direction, because of the large scale crystals, going through the second polarizing filter and so we’re able to see a difference there.  Where are the droplets?  The droplets are all gone.  Right, and what I’ve got there, this is definitely gel phase, the one in the upper right corner.  Is it the one we would have expected?  It’s the high water, warm sample.  Yes, that’s the one we would have expected to gel first.  
There’s 120 minutes.  There’s 180 minutes.  Which one is that?  That’s the medium water, warm sample.  Now the ones that are left are the high water cold sample.  Why is the high water cold sample not gelled?  Not warm enough, right?  It’s not warm enough to get to the gel phase.  Why is the medium water cold sample not gelled?  Not hot enough.  
240 minutes.  Oh, there we go, 300 minutes.  High water cold has reached gel phase, the medium water cold hasn’t reached gel phase.  
And there’s eight hours later.  The medium water cold sample never reached gel phase because it was cold and remember what happens for medium water, it has to reach a higher temperature than a low water soap does.
I’m going to go through this again, and I just want you to watch this one.  Don’t watch the others.  
There we are at zero minutes.  Just pay attention to the lower left quadrant.  So what’s happening to it?  It’s getting darker and darker.  Soap is forming.  It’s not that soap isn’t forming.  But what kind of soap is forming?  Little crystals, the same size as the wavelength of light.  The light comes in and bounces off instead of going through.  So it never makes it.  As the soap forms, it’s forming tiny little crystals instead of large crystals.  And that’s going to have important consequences for us.
What I want to do now, do I have time?  How long do I have?  Okay, so I’m going to go through these one at a time, let’s get out of this.  And I’ve got four video clips that we can watch.  They are each eight hours long, condensed into two minutes.  So each one of these is two minutes long but you can think that two minutes is actually eight hours of video.
So let’s do, oh there they are.  Let’s do DD144-40. (please refer to first video below)  This is the cold medium water soap.  
Okay, there we go.  This is the cold medium water soap.  What I want you to notice here is this little halo.  There’s some color there, there’s some crystals forming here at the edge of the lye droplet.    KD – No, he had two semesters, he had the fall and spring.  He did get an “A”.  
Look, look, see these?  Those are little soap crystals forming and it’s becoming opaque as the light can no longer pass through it.  You see this halo here, those are some larger crystals that are trying to form.   KD – 8 hour period.  We’re about halfway, we’re about four hours in now.  We’re not getting large crystals, we’re getting small crystals forming.
  
So, it’s hard to see since it’s happening so gradually, but the whole thing is getting darker and darker and darker as the crystals are forming.  And you can actually see little pockets, it’s as if once one crystal forms, it’s easier for the next one to form next to it. 

  KD – Because after 8 hours, it gets really boring.  Pretty much anything that hasn’t happened in 8 hours is just never going to happen.
Okay, let’s do the same medium water soap, DD144-60. (please refer to second video below)  This is the warm medium water soap.
Oh look, look at this.  Already, there’s a little, oh and look here and here.  And you’ll see, once one starts forming, it’s easier for the others to form around it.  This is a warm sample so things are happening quicker.  Look, these are getting darker and darker and darker.  Little crystals forming, right?  Little crystals forming in the lye bubbles.  Look at the halo around this guy.  A large crystal is starting to form at the edge of the lye bubble.  
  KD – And it just went over to gel phase.  You can see there’s a little ghost of a circle here where a little lye bubble used to be, but now it’s like a fossil.  It’s a fossil lye bubble now filled with neat soap.  Now you see why 8 hours is enough, because you know what, this is done.  You can skip to the end and we’ll save like 45 seconds, and there’s really nothing left for this guy.
Let’s do DD288-40. (please refer to third video below) This is the high water cold soap.  Now you can see, soap is forming.  Little crystals are forming.  
We’re about four hours in now.  This has changed, we’re starting to see… And it’s really cool again, here’s a little fossil, it’s filled with soap but the soap in here is pointed in different directions than the soap that’s around it.  And that comes out as a different color under polarized light.  And again, this is now boring, we can skip to the end.  Nothing has changed.
And now this is the high water warm soap. (please refer to fourth video below)  And this is fun, look.  We’ve got a little chasm here of unreacted oil.  It’s kind of cracked and the little pocket’s surrounded by soap but somehow the sodium hydroxide isn’t finding it.  We’re about an hour in now.  And I’ll let this one go all the way through because you can be cheering for this guy.  If he ever can make it.  He’s not yet made it, there’s a little island of unreacted oil still left there.  
Come on, I know you can do it.  You can see it’s trying at the edges.  But remember what’s happened.  Almost all the lye has already reacted over here.  There’s not a lot of lye left.  And we’re talking two or three hours in.  Almost all the lye has already been consumed.    KD – He had to be very quick, because we’re not putting it on a flat microscope slide.  We have to protect both the top and the bottom and it has to have a uniform thickness.  So we’re using rectangular capillary slides.  He had to invent a whole procedure for getting thick soap into a tiny tiny thin glass tube and get it onto the microscope without much delay.    KD – He was doing his best, but if he’s going to err, he had better err on the side of getting it in soon, rather than late.  Sucking raw soap into a tiny little glass tube when it’s already thick is really not a fun things to try.    KD – Yeah, yeah.  And so the hot process people, that’s what they’re doing and as they’re stirring them up, banging them together and they assemble into larger crystals.  The stirring is also accelerating the process.
Alright so let’s go back to the slides.  And we’ll see, is there any difference.  Okay, so you can make soap over a wide range of water compositions and you get to choose, by choosing the initial temperature, you get to choose how hot it is eventually going to be.  If you want your soap to gel, you have two measures of control.  What can you change if you want it to gel?    KD – What are you going to do with the water?  Increase the water, that’s one way you can do it.  Or, increase the temperature.  You’ve got two ways that you can go there.  You can do either one or the other, or you can do both.  If you want to prevent gel….   KD – Decrease the water or decrease the temperature, and you won’t get gel.  Now some of you talked about partial gel, have you ever seen that?  What does it look like?  You’re nodding your head, describe for the people who have never seen it before – what partial gel looks like.>
  KD – That’s the third.  You can increase the water, not in this batch, it’s too late for that batch.  But for the next batch, you can increase the water in your formula, that’s going to lower the temperature that it takes to get to gel.  You can can increase your initial temperature, that’s going to raise the eventual temperature so that it may all gel; and the third way is insulate your mold.  Why did it not gel on the outside?  Because it was warm in the middle and cool on the outside.  If you can make it warm on the outside, as warm as it was in the middle, you’ll probably get to a full gel. 
Okay, do we care?  Is there any difference?  So we’re going to compare high water soaps processed at different initial temperatures.  If I look at them, they have the same consistency.  You can see it when they’re right next to each other, you can see the line between the gelled and the ungelled soap, but if you have two different soaps and you’re just looking at them one at a time, it’s hard to see the difference.  Same consistency, we measured the alkalinity.  The alkalinity was identical.  We had the same hardness, both soaps were equally hard.  
So, is there any difference?  When we soak them in water, they behave differently. This is a really hard and difficult, fancy experiment that requires enormous amounts of technical expertise.  We cut soap into little cylinders, why not squares?  Because we have a thing called a cork bore which drills cylinders and so we used a tool which was never intended for that, and it’s more fun.  So we have little cylinders of soap, they’re stuck on a little shish kabob skewer, they’re hung in a plastic cup at room temperature in water for 16 hours, sorry, 18 hours.  And what we’re going to do is, after 18 hours of soaking, what do they look like.
There it is at zero hours.  
Here it is at 18 hours.  Can you tell a difference?    KD – It’s not like night and day, is it?  It’s not like, oh yeah, it’s not like red and blue.  If you use your imagination, look at the swelling here, and look at the swelling there.  If you compare the ones on the end, you have the easiest time of seeing the difference.  Also, what I can’t do is, you can’t squeeze it on the screen.  But if this were the real soap, this is very squishy.  And this, once you get past that initial layer there of soft soap, it’s still hard underneath.    KD – So what is this?  This is all the same, this is all Aq₂₁₆.  All the same amount of water.  This was at 40, 45, 60, 65 and 70.  The ones that were hottest, remained firm longer when they were soaked in water.  I’m not yet talking gelled.  We’re just looking at the picture there.
So, I’m always thinking, well, what could be wrong with what you just said?  Is it that these were gelled, is that the difference?  They were also at higher temperature.  Maybe it was simply being hot that was important, and not being gelled.  So can we test that?    KD -  I don’t remember that.  I simply don’t remember it.  But this is also in the…, this picture is in the book, I think.  So it will tell you the details.  
So we wanted to look at a different thing to see if it’s being hot that’s important or being gelled that’s important.  So, these were all at the same temperature.  But different amounts of water.  And we see, the high water soaps at the same temperature, the two of them that gelled remained firm, and the ones that didn’t gel are soft and squishy.  
Now I’m going to make something up.  I want an explanation why is that the case?  And we remember from the microscopy, how big are the soap crystals when they don’t gel?  Small crystals.  Big crystals vs small crystals.  Little crystals dunked in water, the water immediately penetrates around them and starts dissolving those soap crystals.  A large soap crystal, the water has a slower time to penetrate into the crystal and get it to be solvated.  Now , I can’t tell you with 100% confidence that that’s the reason, but it makes sense to me that little crystals would solvate faster than big crystals.  

So how does that translate into the real world, exactly right.  Make a prediction now of how soap would behave in regular use depending on whether it gelled or whether it didn’t gel.  

I would think you’re right.  And you guys can actually test that.  If you have a partially saponified bar, you can put it in a soap dish and you can watch it.  Does the soap on the outside, does it swell up and flake off and leave a core, a circular or oval core of soap that’s relatively firm?  I haven’t done that.  That’s something that you can do to answer that question.
  KD – It may be that they are getting warm and those little crystals are combining together slowly over time.  So I don’t know that.
  KD -  See, isn’t this cool?  This is a choice that you get to make.  Isn’t that cool?  So some people might like it.  They might think, wow, this stuff, when I use it, it really lathers up quickly. Because the water is getting in there.  Other people are complaining, you know, I’ve had that bar for two weeks and it’s already gone.  Or, it sat in the soap dish and now it just completely turned to mush.
So I’m not telling you right or wrong.  I’m giving you another tool that you can use to intentionally process your soap. 
Okay, so the phase behavior depends on the size and the shape of the mold.  What do you think?  Big mold, big mold is going to retain heat longer.  There’s only going to be a thin rind of cold soap on the outside as opposed to a tray mold that has a lot of surface area, a lot of places for heat to escape.    KD – Wooden vs plastic, insulated, wrapped in blanket vs not wrapped in blanket.  Oven processed, cold process oven process soap vs cold process room temperature soap.  The initial temperature is something that you get to control.  And the water portion is something you get to control.  You’ve got three ways that you can control the process.
And you get to choose the oil.  We didn’t talk about this, but saturated fats saponify more quickly than unsaturated fats.  So you get to control that as well.
Fragrances and additives.  The fragrances and additives you add may accelerate saponification or retard saponification and that could also make a difference.
Alright, so, wow, is that perfect or not?  

medium-water cold

medium-water warm

high-water cold

high-water warm

 

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