“The Balancing Act, Part I”, presented by Dr. Kevin Dunn.

Dr Dunn talks about lye, particularly how and why it can “go bad,” what “bad” lye does to soap, and how to detect bad lye.

It seems like only yesterday that we were here and it’s going to be a long time before November, so we’ve got to get everything in that we can today.   I want to start out with some acknowledgements, of course, Derek of Essential Depot has been a great supporter of our work, Mike Lawson of Columbus Foods was an early supporter and a very good supporter, Hampden Sydney College where I teach has been very good at tolerating a “nut” job like me, and each semester I have some students work on projects.  This semester I’ve got Andrew Fisette, Matthew Chapman, Jefferson Thompson, and most of the work that I’m going to talk about today was done by Mitch Owens.   So I’m going to work in two parts.  First, how many of you know how to calculate saponification values?  All right - not?  I think most people are terrified of the math.  Am I right?
Group		Yes
Kevin:		So I’m going to walk you through that and even if you use a lye calculator, wouldn’t it be nice to know what the lye calculator is doing?   And what do you do if you’ve got something that isn’t in the lye calculator.  So we are going to talk about that this morning.  
The second part we will be talking about when lye goes bad.  Does it have a shelf life, what can go wrong with it, how can you find out what went wrong with it and what can you do with lye that has gone bad.  Anyone interested in knowing about that?
Group		Yes, yes
Kevin		We are going to talk about that this afternoon.  But first, I have got some sodium hydroxide here and we are going to weigh some out and I want you to record the answer for me and we are going to check it this afternoon.  So the cup weighs 2.59 grams, you can write that on your slides, I have some fresh out of the bottle sodium hydroxide from a little place called Essential Depot and it now weighs 13.74 grams, including the cup.  Because we are going to weigh it later and we are not going to be able to take the cup away, that would be pretty messy.  So right now 13.76 grams, and I’m going to just leave this out, where it won’t be disturbed.  I will put it somewhere later.   And we are going to check its weight this afternoon and see if the weight has changed over the course of the day.
Elsa:		What did you weigh it on, your phone?  That’s what I’m thinking
Kevin		Well I’m going to be talking about that.  I don’t know whether I will get to that this morning, but certainly this afternoon I will be talking about that little gem there.   So some of you will be bored in the next four minutes, so you can go to sleep, because it’s review, but we have new people here, so I want to talk about oil and water.   Oil and water don’t mix and some of you can come up and give the speech that I’m about to give.  It’s about nerds and cheerleaders.  
Kevin		So tell me about nerds and cheerleaders.  What’s going on there?
Elsa		They want to be friends but they just don’t know each other that well.
Kevin		And what’s the major point, the major point is not that nerds hate cheerleaders, it’s not the cheerleaders hate nerds, it’s that
Elsa			They want to be with their like kind.
Kevin			Cheerleaders like cheerleaders more than they like nerds and that’s all that’s necessary and high school cafeterias across the universe, cheerleaders are sitting together and nerds are sitting together.  The cheerleaders sitting together because they like other cheerleaders more than they like nerds.  The nerds are sitting together because there’s no place left to sit.   So oil and water are like that.  Oil is like the nerds and water is like cheerleaders.  Water molecules are attracted to one another more than they are attracted to oil, so water tends to congregate together and the oil goes wherever the water isn’t.  We say that it’s hydrophobic but it doesn’t mean that it really fears water.  
So this is what the kind of oil that we use is a triglyceride.    It’s got four parts to it.  This is what oil looks like before it’s turned into soap.  We have added some hydroxide ions, those are the three little things and you can see that the oil molecule is like a hand with three fingers on it, and when the hydroxide attacks that molecule, “dink”, one comes off and that little finger that has just been amputated is a soap molecule.  I have got two more hydroxides left, “dink” there it goes again and I have two soap molecules, and now “dink” I have three soap molecules and that thing in the middle, the knuckle where the fingers used to be attached, is glycerin.  So that’s the basic chemistry of what’s going in whenever you mix oil with water.
All right, soap is a nerdy cheerleader, it’s a Siamese twin.  Part of it is a nerd and part of it is a cheerleader.  Part of it is hydrophobic and part of it is hydrophilic.  The hydrophilic part will be congregated with water molecules, so in water the polar head group, the hydrophilic head group will be attracted to water molecules and the hydrophobic tail will be, I won’t even say attracted to oil, it just goes wherever water isn’t like all the oil does, and so this forms a bridge between oily things and watery things and when we use soap, mostly what we are trying to get rid of is oily things.  If they weren’t oily, we would just wash our hands with water and be done with it.  
All right, this is an example of a fatty acid.  This is stearic acid and on the top I have shown you a molecular structure of it and the color coating here is green is hydrophobic or hydrophilic?
Group		Hydrophobic
Kevin		It’s hydrophobic, that the hydrophobic tail and the red and white atoms at the head are the hydrophilic part, those are the parts that are attracted to water molecules.  Underneath there is a stick structure.  It’s hard because you’re sitting around talking at the table, you can’t draw a figure like a molecular graphic at the top, so we just kind of scribble things down, we draw the hydrophobic tail just as a scribbly line and at the head we see two oxygen atoms.  The two oxygen atoms is what is going to form the hydrophilic head and now we can talk about just drawing on napkins, we can talk about the chemistry of soap.   This is a fatty acid, not a soap, what’s the difference between the two?  Remember from the last time?   Just one hydrogen atom different.  So the fatty acid has a hydrogen stuck to the hydrophilic head and a soap molecule doesn’t. Hydrogen has been replaced by sodium in that case.  This is allelic acid and allelic acid is a fatty acid that is unsaturated.  It doesn’t have the maximum amount of hydrogen that it could have and that puts a kink right in the middle of the molecule, and the kink is what makes liquid oil liquid, where solid oils are solid.  Most of your saturated fats are solid at room temperature, most of your unsaturated fats are liquid at room temperature.  Here are the saturated fatty acid that we deal with most frequently.  At the top is lauric acid, that’s the shortest of them, then myristic acid, palmitic acid and stearic acid, and this is a lot to see in one slide, but all I want you to do is to get use to that squiggly line, stick structure, and if you look there is something called a molecular weight there and molecular weight tells you how many grams a mole of molecules weighs.  If you are scared of the word mole, don’t worry about it, we are going to get to that, but they’re proportional.   So of these fatty acids, which one weighs the most?
Group		Stearic
Kevin		Stearic weighs the most and which one weighs the least?
Group		Lauric
Kevin		Why does it weigh the least?   It’s shorter, that’s the only difference.  So we’ve got fatty acids that are relative short and fatty acids that are relatively long.  
Here are the unsaturated fatty acids and the oleic acid has one kink in it, linoleic acid has two kinks, linolenic acid has three kinks in it and there is another kind of weird one, it’s the only one like it, it’s ricinoleic acid and it has an extra OH group right smack in the middle of the molecules.  If you look at the weights, let’s just remember the weights of the previous slide.  What is the heaviest of these fatty acids, saturated fatty acids?
Group		Stearic
Kevin		Let’s stick a number in our head.  What is the weight of that stearic acid?  
Group		___
Kevin		Just remember that for like 12 seconds and compare that weight to these weights.  These are the unsaturated fatty acids.  They are really really close and why are they really really close?  They are the same length, they are all 18 carbon atoms long.  So the unsaturated fatty acids are about as heavy as the heaviest of the unsaturated fatty acids.  All right, we have a new word for you and it’s a fun word and you can trot it out and then impress all your friends called stoichiometry.   Say it with me.
Group		Stoichiometry.
Kevin		That’s one word that has a very simple meaning.  All it means is how much of this goes with a given amount of that.   You’ve got a cake recipe.  How many eggs go into a cake recipe?   And it depends on how big the cake is right.  It depends on how big the cake is.  So you have to say I’m making a single layer cake this big, how many eggs, two eggs.  If I’m making a three layer cake, how many eggs, six eggs, that’s stoichiometry.   It’s a fun word to say.   We’re going to apply stoichiometry to soap, how much sodium hydroxide is needed to react with a given amount of oil.  That’s the fundamental stoichiometric question.  How many molecules of sodium hydroxide are needed for each molecule of oil?  You remember our graphic.  How many fingers were on the hand?
Group		Three	
Kevin		Three fingers, how many hydroxides did we need?  One for each
Group		One for each
Kevin		One for each finger.  So for each molecule of oil how many molecules of sodium hydroxide do I need?
Group		Three
Kevin		I need three molecules of sodium hydroxide for each molecule of oil.  Now here is a more difficult question.  How many dozen sodium hydroxide molecules do I need for each dozen of molecules of oil?
Group		Three
Kevin		Wow, you did that really quickly.  I didn’t even see anyone whip out a calculator.  Three dozen sodium hydroxides to react with one dozen molecules of oil.  How many gross of sodium hydroxide to I need to go with a gross of oil?
Group		Three
Kevin		Wow, you guys are really sharp.  Okay, here is the hardest of them all.  How many moles of sodium hydroxide do I need to go with a mole of oil?
Group		Three	
Kevin		Now you don’t even know what a mole is.
Group		Laughter
Kevin		And you know the answer already.  You don’t even have to know.  If you want to know I’m about to tell you.   How much is a dozen?
Group		Twelve
Kevin		How much is a gross?   144.   A mole is 1.23 x 10 with 22 zeroes on the end of it.  That is a big number, but the good news is that it doesn’t matter.  All that matters is we’re using the same unit for the sodium hydroxide as we are for the oil.  It’s just a number, and it is a three to one ratio however big or however small that number is.    Are you still scared?
Group		Maybe
Kevin		Maybe a little.  If you’re honest, you are still a little scared.  All right, we need to talk about atomic weights now.  How much does a mole of atoms weigh, and the weight of the mole of atoms depends on what the atom is.  A mole of hydrogen weighs 1 gram.  A mole of carbon weighs 12.  A mole of oxygen weighs 16 and a mole of sodium weighs 23 and a mole of potassium weighs 39.   So where did I get these?  You have all seen it probably.  It is on a periodic table.  There are two little numbers for each element and this is one of them.  I don’t even care if you know what the other one is.  This tells me for that giant ginormous number of atoms or molecules, how much does that ginormous number weigh, and it depends on which atom I’m talking about.  If I’m talking about molecules, all I have to do is add up the atomic weights.   For sodium hydroxide, it is 23, that’s what?  Twenty three is which element?
Group		Sodium
Kevin		That’s sodium and 16 is the oxygen and 1 is the hydrogen.  If I add those up, 23, 16 and 3 add up to 40 and 40 is the molecular weight of sodium hydroxide.  Potassium hydroxide is almost the same material except it has a potassium instead of sodium.   Sodium weighs 23, but potassium weighs 39.  If I add 39 to 16 and 1, I get 56.  So that is why when you are making soap it matters to you whether you are using sodium hydroxide or potassium hydroxide, the molecular weights are different.
Now we need the molecular weight of this oil molecule.  All right let’s get busy.   You’ve got a graphic there.  Count up all the carbon atoms, those are the green ones and multiply them by 12, and each one of them is surrounded by hydrogen atoms, add those all up, those are multiplied by one.  We’ve got some oxygen atoms there, six oxygen atoms in the molecule, that’s each one times 16 and well maybe I’m not going to do that by just counting, but I could.  If I did, trilaurate, that is the glycerin with three lauric acid molecules attached to it, would be 638.95 grams, tripalmitate would be 807 grams.  Why does glyceryl tripalmitate weigh more than glycerol trilaurate?
Group		Because it is longer?
Kevin		Exactly. Because the palmitic acid is 16 carbons long, but the lauric acid is only 12 carbon long and each carbon atom has some weight.  So we are going to remember those numbers.  All right, how many moles is in a kilogram of oil?   I’m going to give you a little toy problem first.  Which has more in it, if I have a pound of grapes or a pound of apples?  Which one has more grapes or more apples?   In a pound of grapes there are more or less grapes than there are apples in a pound of apples?
Group		Grapes	
Kevin		Wow, you guys are really.  How in the world are you doing that?   Because grapes are smaller than apples.  So how would you do that mathematically?  You would divide one by the other.  We are going to take 1000 grams and divide it by 638.95, 638.95 is what?   Okay, say it with me, mol, mol, 
Group		It is the molecular weight
Kevin		It is the molecular weight of glyceryl trilaurate.   So I divide the weight that I’m interested in by the molecular weight that tells me how many moles.  In 1000 grams of glyceryl trilaurate, I’ve got 1.56 moles.  Now that’s a lot easier than 6.23 times 10 and 23rd.   So glycerol tripalmitate is one kilogram, how many moles?   1.24. Why are there only 1.24, because they are bigger molecules and in a 1000 grams of oil there will be fewer molecules then there would be if the molecule had been smaller.  All right, now that I now that, how many moles of KOH do I need to react with that kilogram of oil?   Glyceryl trilaurate and how many moles of KOH do I need for each mole
Group		Three
Kevin		Three to one.  Three times 1.56 is 4.68.  If it were glyceryl tripalmitate, it would be 1.24 x 3 or 3.72. The numbers are different because the molecules are different size.  Which one needs more KOH, the little molecule or the big molecule?
Group		The little molecule.
Kevin		The little molecule needs more grams of KOH per 1000 grams of oil because it’s smaller.
How many grams of KOH is needed for a kilogram of oil?  Well now I have to multiply by the molecular weight.  Before I had the number of moles of KOH, now I need the number of grams of KOH, because you know what, there is no such thing as a mole-o-meter.   I can’t go out, google mole-o-meter, you won’t find it anywhere, and nobody makes such a thing that measures out moles.  We weigh things out on a scale or balance and so we need to convert it to weight.  One mole of KOH weighs 56 grams, so for glyceryl trilaurate, I need 262, but for glyceryl tripalmitate I only need 208.  Do those numbers look at all maybe and possibly, sort of, in any remote way familiar to you?  Ah, well we’ll see.   How many of grams of sodium hydroxide do I need?   Well it’s exactly the same number of moles, because it doesn’t matter, it’s the hydroxide that is reacting, it doesn’t matter if it is NAOH or KOH, but NAOH weights more or less than KOH?
Group		It weighs less.
Kevin		It weighs less, so when I multiply it out, I get 187 and 149.  Do those number look in any way possibly familiar to you.
Elsa		Yes
Kevin		What are they?
Elsa		I remember from up above
Kevin		Hopefully in a few minutes you will say, ohhhh!  Okay, it is here it is all in one slide.  It is the most terrifying slide in my entire presentation.  But it is exactly the same math that we’ve just done, it is just done all at once.  I asked how many grams KOH are needed for 1000 grams of glyceryl trilaurate, 638.95 is the say it mole.  The molecular weight of glyceryl trilaurate that converts it to moles.  I’ve got a three to one ratio of KOH to glyceryl trilaurate and each mole of KOH weights 56.11.  That gets it all done in one giant fell swoop, I get 263 and I’m going to use a word here, parts per thousand.  Parts per thousand means how many parts, how many grams per thousand grams.  You’re use to something called percent.  What is percent?  Percent is parts per hundred.  This parts per thousand, it’s just got one more digit on it.   
This sodium hydroxide I get 188 parts per thousand.  In practice, we don’t know the molecular weights.  We would be done if we could just look up what the molecular weight is of coconut oil.  What’s the weight of palm oil, but these things are not pure compounds.  They are mixtures of all kinds of different fatty molecules and so in practice what we have to do is measure how much sodium or potassium hydroxide does it take to completely saponify one gram of oil.  That’s listed in a table of saponification values Scientific Soapmaking has a table in the back, but it’s different from the tables for most of your soapmaking books, in that it doesn’t have one number.  It has a range of numbers.  So glyceryl trilaurate was 187 parts per thousand in decimal, that .187.  Glyceryl tripalmitate was 149, that’s decimal .149, coconut oil is a range of 176 to 189, or .176 to .189, and palm oil is .135 to .149.  Now do you seem any similarities?  
Group		They are SAP values
Kevin		They are SAP values.  Compare the SAP value of glyceryl trilaurate to these real world oils.  Which one is it most like?  It is most like coconut oil.  That isn’t an accident.  It’s because coconut oil contains mostly glyceryl trilaurate in addition to other fats, and which one is glyceryl tripalmitate most similar to?  I wonder how they came up with the name, palmitic acid.   It’s because they isolated it first from palm oil.  I said, in a minute you’ll go “ohhh” and you just did.  So these numbers start to mean something other than just numbers in a book.  If you look for SAP values of coconut oil, how come the SAP value of coconut oil is bigger than the SAP value for palm oil?
Elsa		Because it’s heavier.
Kevin		Because which molecules are bigger.  The palm oil molecules are bigger than the coconut oil molecules and, therefore, the SAP value for, oh it is exactly backwards isn’t it.  The SAP value of the coconut oil is bigger than the SAP value for the palm oil.  Because there are more molecules in a given weight of coconut oil than there are molecules in a given weight of palm oil. That is what it was for KOH, here is the same numbers, there we go, and there is sodium hydroxide.  
Lye calculators use an average value.  That is why you get only one number.  If you look up coconut oil in a typical soapmaking book, it will tell you what the saponification value is.  Sorry life isn’t that simple.  Coconut oil changes from one supplier to the other: where was the coconut grown, what was the season of it, it changes, so we get a range of saponification values, not a single number.  So soapmaking books will say taken the average number, so they don’t even tell you that it is an average number.  Take the average number and now they recognize that some coconut oil may have a lower or higher saponification value.  What is the one thing you want to avoid?
Group		Too much lye
Kevin		Too much lye.   We don’t want to have too much lye, so they say take the average value and discount it.  What do we mean by that?   Use less, you are going to calculate how much you need and then you are going to use less than that.  I take a slightly different approach.  I say, you know what, there is a lower limit, let’s just use that number.  Then you are guaranteed that any coconut oil you find is not going to have a higher SAP value than that, and that way you’re guaranteed not to have an over alkaline soap.  It doesn’t matter which way you do it, you can do it both ways, but that’s the way that I prefer because it is a guaranteed result rather than just going on an average.  
So now we have four different oils.  We have coconut oil, palm oil, olive oil and castor oil.  And here are the SAP values for each one.  How many pounds of sodium hydroxide, okay that’s what’s going on here.  I have to remember what’s going on here, so this is grams, this is pounds.  How many pounds of sodium hydroxide are needed for a pound of oil?  Oh for coconut oil it is .176, for palm oil it is .135 and that’s in pounds, pounds for pounds.  How many grams of coconut oil?  280 x .176, gives me 49.28 g of NaOH.  It’s simply multiplying however much weight of coconut oil you have by the saponification value as a decimal, 280 g requires 49.28 of NaOH.  For palm oil, I want 280 g of palm oil, I multiply by .135, where did I get .135?  It’s the SAP value for palm oil, multiply those two together and I get 37.80 g.  Here’s a trick question.  If I need 49.28 g for the coconut oil and I need 37.80 g for the palm oil, how much total do I need?  
Group:		You just add them up.
Kevin		I just add them up, 87.90 grams total.  Now I’m going to add 390 g of olive oil.  Well that’s 390 g x .131, what is that, SAP value for olive oil?  I need 51.09 g for the olive oil and for the castor oil, 50 g x .125, tells me how many grams of NaOH I need for the castor oil.  How much total do I need?  It’s not brain surgery, I just add them up.  I needed this much for this one and this much for that one and the total is just adding them up.  144.42 g of NaOH.  Wait a minute.  280g of coconut oil and 280g of palm oil and 390g of olive oil and 50g of castor oil adds up to 1,000g of oil.  Now how many grams of NaOH do I need for 1,000g of this mixed oil, 144?  144 is the saponification value for this oil mixture.  If you’re master batching you can calculate the SAP value, not for the individual oils, but for the master batch of oils that you mix up.   All right, I call this Duckbar’s delight.  That’s the name of the oil mixture and if I have 16 oz., how many ounces of NaOH do I need?  I just multiply 16 x .144, that’s the SAP value for the mixed oil, 2.3 oz.  All right, here is a practice problem for you.  Your formula calls for 56 oz. of coconut oil, 56 oz. of palm oil, 78 oz. of olive oil and 10 oz. of castor oil.  How many ounces of NaOH are needed?   And this is not a rhetorical question.  You now have some work to do.  You can work in pairs and I want an answer in the next….
Group		What is the saponification value?
Kevin		Remember it is written on the previous line, .144 is the value for the mixed oil.  Now about three of you are taking me seriously and working it out, but I’m just going to stand here until you’re done, so you want to check your e-mail or whatever it is you got going on.   They will probably put a commercial in the video at this point.   Okay you’re ready?  You’re exactly right.   Let me just think about this for a second.  I had 280g and 390g and 50g, look at these numbers.  56 oz., 56 oz., 78 oz., 10 oz., the ratios are exactly the same except this is like twice as much and it is in ounces instead of grams.  It is twice as much, oh, 14.4 x 2 is 28.8.  All right, that was the right answer, and it doesn’t matter now, it doesn’t matter whether you want to work in grams, it doesn’t matter if you work in ounces, it doesn’t matter if you want to work in pounds.  The thing you want to do is use the same unit throughout.  If you do, the calculation is exactly the same.   There is only one thing you want to avoid.  You don’t want to work in pounds and ounces.  Then you got to convert.  You work in ounces or work in pounds.  So, if you make that choice the calculation is as easy as what we have done so far.  All right, I have 15 minutes, this is where I intended to get the end of the hour, but I want to leave lots of time this afternoon to actually roll up our sleeves and get our hands dirty.  So I’m going to march ahead and give you the kind of the intro to what we will be doing this afternoon.  
When lye goes bad.  In the world, when you go out in the world, people will use three terms synonymously, they’ll talk about lye.  When they are talking about lye what do they usually mean, sodium hydroxide, or kind of the old word for it is called caustic soda.   I’m going to use the three words, not synonymously.  I don’t really want you to go out in the world and tell people that they are wrong to use them synonymously, it just is that we have three different things and I want to have words for them so we can talk about them.  So when I talk about caustic soda, even though this bottle is labeled is sodium hydroxide, I am going to refer to it as caustic soda.  It’s the white stuff in the bottle that you got from somebody that sells you caustic soda.  What chemical is in caustic soda?
Group		Sodium hydroxide
Kevin		Sodium hydroxide.  So I’m going make a distinction between sodium hydroxide, the chemical, and caustic soda, the white stuff in the bottle.  And, furthermore, when I dissolve this white stuff in water, I’m going to call that lye.   And that kind of follows the original meanings of these words.  It is not that they were ever used that precisely, but I want to know draw that distinction between the caustic soda, the white stuff in the bottle and sodium hydroxide, the stuff that you need to make soap, okay?   When you leave this afternoon, I don’t care if you use them synonymously, but at least for the purposes of our talk, I am going to use them very specifically.  This is the Certificate of Analysis of Essential Depot’s caustic soda and I know that you can’t read that so I blew it up.   So if you see a bunch of numbers in here and at the top is FE, anybody know what that symbol is for?
Group		Iron
Kevin		Iron, this is how much iron is present if the unit is parts per million.   So this stuff is allowed to have up to 15 parts per million iron.  Why is it allowed to have any iron? 
Group		Because it is graded on a tech grade?
Kevin		 This is food grade and it is allowed to have 15 parts per million iron.  How much is a part per million?  Remember we thought parts per thousand and parts per hundred.  Parts per million is really tiny.   The number isn’t zero because you know what, you aren’t going to find anybody anywhere in the universe to sell you something with zero parts per million iron.  They might get it down to one, and if you wanted one part per million iron, you would be paying a lot of money.  Because to get that last little bit of iron out is very expensive.  How about mercury?   Do you like to have mercury in your soap?
Group		No
Kevin		Well we’re allowed to have up to .1 parts of mercury in food grade sodium hydroxide.  Because if you wanted less than that, you wouldn’t be able to afford that sodium hydroxide.  So these are upper limits.  Sodium carbonate is 1.6 and what’s the value, percent up to?    1.6 percent by weight.  Why don’t they have that to be less, and notice it’s a bigger number right, a percent is a lot bigger than a parts per million.  Why do we allow so much sodium carbonate in here?  Well, we’re going to find out.  I’m not going to spill the beans there.  Sodium oxide is what you would get if you removed all the water from sodium hydroxide.  NaOH, well you know it has an O and an H in it and if you took those out and just had sodium hydroxide up to 100 percent of that, sodium chloride up to 2.3 percent, so you see what these are and then the ones at the bottom, these are meshes, so this stuff is of a consistent particle size, they have run it through a screen and this says that your 100 percent will pass through a 16 mesh screen, but only 2% will go through a 60 mesh screen.  So it means the particles are of a consistent size.  
Food grade is different because, you know, if it is food grade, what if it weren’t food grade?  How much mercury would I allow in a nonfood grade sodium hydroxide?  Probably more, right?   Would it be more expensive or less?
Group		Less.
Kevin		It would be less expensive.   All right, the Certificate of Analysis tells you the information about the quality of the product as measured by the manufacturer. The most important contaminants are not even listed. The most important contaminants though are not even listed.  The most important contaminant in sodium hydroxide isn’t even on the Certificate of Analysis, because they can’t control it that well, it’s water.  Now I can avoid adding water to sodium hydroxide but I can’t absorb sodium hydroxide from getting water.  Where is it going to get it?
Group		From the air.
Kevin		From the air.  It gets it right from the air and we poured some in a cup and we’re going to check it.
Elsa		No, it’s on the table Dave.
Kevin		It’s on the table.  It probably hasn’t picked up any weight yet, but let’s check it out.  What was the number that it weighed before?
Group		13.76
Kevin		The weight now is now 13.85 grams.  What was it before?
Group		13.76
Kevin		Already, it has picked up some water.  So we are going to leave it there all day.
Group		Was it 13.84?
Kevin		It was 13.80, I have a mind like a sieve.  They could pass this stuff through my brain and it would come out a consistent mesh size.   It was 13.84, 13.85, the last digit will jump around a little bit.  13.85 is what it is right now.  So, they can’t control that, the manufacturer has some control of the product as it leaves their factory, but then it comes here and they buy it in giant lots of sodium hydroxide and then they break it down in smaller bottles, and you know what, in order to do that they have to open the bottle right?  And, hmmm, Florida, probably not much humidity here, I don’ think, probably not, probably not.  So some moisture is going to be picked up as they are breaking it down into smaller packages and now Derek is doing his best to get you nice dry sodium hydroxide, but then you get it to your shop.   I wonder what shops are in the basement?
Elsa		We don’t have basements in Florida
Kevin		Not in Florida, but you don’t need a basement.  All you need is the atmosphere.  But a lot of soap shops are humid, so every time you open a bottle it picks up moisture from the air and it picks up one more thing from the air, it picks up carbon dioxide.  Carbon dioxide is an acid, sodium hydroxide is a base, so you’re sitting there in the soap shop, you’re working away, you’re huffing and puffing, you’re exhaling carbon dioxide and you left the sodium hydroxide open, it’s not a catastrophe, I don’t want you to be paranoid that you have to put the top on twelve microseconds after you opened it; but the longer that bottle is open, the more moisture and carbon dioxide it picks up from the air.
Okay, how many of you think that you have had a bad batch of sodium hydroxide before?   You don’t hear about it a lot, but you hear about it occasionally.  I wonder what happens when I make soap with bad sodium hydroxide.  Normally when Duck Bar Delight using a master batch oil, 50% lye, a bar of soap can be made with 100 grams of oil, 28.8, there’s that number again, 28.8g of lye, 14.4g of water, that’s equivalent to 14.4g of sodium hydroxide and 28.8g of water.  However, if our caustic soda has absorbed atmosphere of moisture, 14.4g of caustic soda will contain less than 14.4g of sodium hydroxide, and that’s the fundamental problem.   If we had 95% sodium hydroxide, that is, that it picked up 5% of its weight in moisture, then 14.4g of caustic soda will actually contain 13.68g of sodium hydroxide.  It would have an extra, 72g of water and we can simulate this.  I tell people, I make bad soap on purpose, one bar at a time, to answer questions and that is exactly what we did.  So, 100% purity, I would use 28.8g of lye, remember lye is the solution, 50% solution, and here I have simulated what would happen if I had 95%, 90, 85 and 80% sodium hydroxide in my caustic soda.   I’ve not given you numbers here for hardness, because my student hadn’t completed the experiment when I made up the slides.   So I’m now going to give you those numbers.  The 100% one you can write in had a hardness of 1.00.  At 95% it was .75 hardness, at 90% it was .35 hardness, at 85% it was .25 hardness and at 80% it was .20 hardness, 1/5th of the original hardness.   You say hardness, how in the world can you calculate hardness and I’m going to leave that until this afternoon.
Okay, thank you very much and look forward to following this up this afternoon.


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