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

Continuing Dr. Dunn’s presentation, testing lye with a precision scale.

KEVIN:		Just to touch base on the some terms we started in the morning, when I talk about caustic soda, what am I talking about?  White stuff in the bottle.  When I talk about sodium hydroxide?
Group		You’re talking about the stuff it’s made of, the main chemical.
KEVIN:		It’s the main chemical in the caustic soda and when I use the term lye?
Group:		It’s mixed with water.
KEVIN:		So it’s mixed with water.  Okay, so the slide from this morning
Kimberlee:	Is it only water or any liquid?
KEVIN:		You know, historically it has always been water, but I suppose if you wanted to make an alcohol lye, I could, in conscience, call it that, oh yeah, coffee, tea, all of those things are mostly water to begin with.  Okay, so this is the slide that we ended with and some kind of fake, made up, intentionally bad soaps to test what happens when lye goes bad and the numbers I gave you were a hardness of 1.0 for the one that was 100% lye and it went all the way down to .2 for the one that was only 80% of sodium hydroxide.  So, I gave you numbers for hardness, you may be used to just feeling a bar of soap and saying, “Oh, that’s kind of soft or that’s kind of hard.”  I want to talk about how do you measure hardness and we use a penetrometer.  Now you may not have a penetrometer, but if you asked your husband to get you a penetrometer for Christmas, then you can tell all of your friends, “Ooh, my husband gave me a penetrometer for Christmas, it’s really really awesome.”   So that’s the penetrometer and you can tell all your friends, “Ooh, it’s got a sliding rubber band and ah it has a nice hard tip to it and the best part is ooh better, spring loaded.”   So this is what we use to measure soap hardness and I didn’t invent this.  In fact, the people that make this have no idea what we’re using it for.  This is for soil scientists to measure how hard soil is, but we have kind of absconded with it for our own purposes, so this is a really nice device.  So if you just google it for an oil penetrometer you’ll find exactly what we’re looking for and they aren’t that expensive.  It allows you then to compare one soap to another and just instead of just saying, ooh, this one’s hard or that one’s soft, you can now put a number to it.  The way to use it is very easy, you just take a bar of soap and you slide the rubber band all the way down to the bottom and this thing is spring loaded so when I push on it, the rubber band stays where it was and I can read a number off of the scale.  The way I use it is that I push it into the bar of soap and thing has a mark ¼ inch and I’m going to push this thing ¼ inch into the soap and then stop and that one got carried away so I’m going to repeat it.  So I just push it ¼ way in and it is now reading out at 1.5. So that would be the hardness of that soap.   You can do all kinds of things, you can compare different oils, you can compare how much water you put in your soap and what you’ll find is as the soap cures, what happens during the curing period?  The water evaporates and the soap gets harder and harder and harder and you can monitor that from week to week to week using the soil penetrometer.  
Elsa:		How hard should a bar of soap be?
KEVIN:		Well actually it can be quite hard.  In fact, so hard that I push it all the way down and it still hasn’t pushed into the soap.  So, I made the accessory and it’s got a smaller foot, since it is a smaller foot, it means it applies more pressure per square inch and now I push that in.  Of course, the rubber band doesn’t move as far because the tip is smaller and I just read that off and then multiply by 2.9 times the reading, will be that reading on the other scale.  So I invented this.  I have yet to market it, but I think Derek might carry this for me on Amazon.
Derek:		What would we call it?
KEVIN:		It would be a Penetrometer Extension.  How about that?  So I’m going to retire off of that.  
Susan:		Can you make us 500 of them before the next retreat?
KEVIN:		Yes I can.  By November, plenty of time.  I can do that.  All right, so we want to measure caustic soda purity.   I’m going to give you an experiment now, my monitor went away, so I’m going to have to turn around.  Okay, in high schools all over the world chemistry students are reluctantly doing titrations and they all think the reason to do a titration is, how many of you in high school did titrations?   Does that word ring any bells?  That’s where you had a glass tube and you dribbled some stuff and then it turned a pretty color.  All over the world chemistry students are being forced to do this and they think the point of the experiment is to see the pretty colors, but that isn’t it.  The point of the experiment is to measure something and in our case it is something that we would like to know.  Would you like to know the percentage of sodium hydroxide in your caustic soda?  So we are going to see a pretty color change, but that’s not the point, the point is getting an answer to that question.  Okay, traditionally the way a chemistry student does this is he has a long glass tube and it’s marked off in divisions and he dribbles stuff into an Erlenmeyer flask and then the liquid that he is titrating comes down and down and down and the color change comes and we call that the end point and then he very carefully reads off exactly how much liquid was used to reach the end point.  That’s the way chemists have been doing titrations ever since God was a child.  When God took general chemistry, that’s the way he did it and it has been done that way ever since.  
Something new has happened in the meantime.  Scales used to be very expensive and they have become very cheap.  Long glass tubes that are very finely marked and calibrated, they’re still expensive. So we are moving in our lab to doing what is called a gravimetric titration.  We are titrating by weight instead of by volume.  All right, so how cheap is it?  Well this is a nice little, now if you ever meet a chemist, would you like to make his eyes pop out?  So, what do you call this thing?  You call it a scale, right, everybody calls it a scale.  We don’t call it a scale.  Chemists call it a balance, because historically a balance was a thing that had weights coming down and the ends went up and down and the needle moved back and forth and you could get very accurate weights off of it.   We’ve always called it a balance, but everybody else calls it a scale.  So if you ever meet a chemist try to work into the conversation, “Oh I stepped on the balance this morning and I’ve lost two pounds,” and his eyes will go “bing” and he’ll go “What, how in the world do you know to call it a balance?”  So anyway, that thing right there will weigh down to a 100th of a gram.  The cost of this thing is $26.08.  Oldwillknottscales.com, that’s the dude’s name.  You can also find them on Amazon.  The maker of this one is Myweigh, and it’s a very nice balance for $26, you get down to 100th of a gram.  The only thing that I would say is wrong with this, is it shuts off automatically after 60 seconds because it runs on batteries.  So that’s not our only choice.  This is an Ohaus balance, it’s also a 100th of a gram, and we call it a centigram balance.  It is $52.40, and the difference is Ohaus, that’s a really good brand.  If you told a chemist that you had a Myweigh balance, he has never heard of that.  If you tell him an Ohaus, Ohaus is a big famous brand for laboratory balances, but it unfortunately turns off after 10 – 30 seconds.  This is a Myweigh i201, and that’s the one I have here and it’s $119.48 from oldwillknott.  If you go on Amazon on the right day, you will find it for under 100 bucks and the nice thing about it is and, oh it also turns off after like two minutes of inactivity, except if you tell it not to.  So you can set it so that it will remain on all the time and it plugs into the wall so the batteries are not going to run out.   So that’s how I’ve got this one set up because we’re in an experiment, you don’t want the thing it to crap out on us half way in between because that is going to ruin the experiment.  That said, we can actually use this guy, we are going to use this and I’m going to show you the way to get around the fact that it’s going to turn itself off.  It will add an extra little step, but you will save 75 bucks, if that’s what you want to do.  This is not a top-of-the-line balance, this is not a Lexus, this is a Toyota.  Ohaus TAJ202.  This is a really really good balance.  It also doesn’t turn off, it’s $170, very rugged and if you wanted a brand-name balance, this would be the one to get.  But, the one I’m using here is no slouch, this is a Kia, okay, so it’s not a bad balance
Group		What about a Tesla?
KEVIN		Well, it’s not a Tesla.  Well we’ve got the Tesla, Tesla is about $1500 and you don’t want that one. It’s an overkill.  That’s an overkill for you.  All right, so we’re going to determine the percentage of sodium hydroxide in caustic soda.  That is what this is all about.  We’re going to do it, I’ve broken it down into some simple steps and then I’m going to change these few simple steps into like a twelve-step procedure so we can follow what’s going on each time.  Mitch Owens is the student who has been working on this, this semester and his best time for a measurement is now under six minutes.  So it is going to take us longer than that to do the first one, the second one is going to go faster and as you get good at it, you will get this thing down to a very quick measurement.  So, we’re going to do an analytical weight and in scientific soapmaking, I make the distinction between a synthetic weight and an analytical weight.  A synthetic weight is you care what the answer is, you want 28 ounces of coconut oil, you don’t want 28.1, you don’t want 27.9,  you want 28.0; so you’re shooting for that and you want to get to that.  In an analytical weight, I want oh about 10 grams of something, I don’t really care whether it’s 10.47 or 9.96, but whatever it is I want to know exactly what that is.  I can give you the analogy when you go to the gas station, because there are two ways to pump gas.  I go to the gas station, I have $10, so I go to the gas pump and I’m squirting, squirting, squirting and then I get to like $9.58 and then I go clickada, clickada, clickada, clickada, clickada and then I go “OH dxxx it $10.01, I’m going to have to fish out a freakin penny.”  So I’m shooting for $10 and I really want to get there, so that’s like a synthetic measurement.  I want to hit that target exactly.  The other one, I’ve got a credit card. It goes urrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrm.  It stopped at $22.53.  I don’t care, I’m going to use a credit card on it, I don’t care.  I don’t care that it didn’t hit a specific target.  Now I do care if it’s $23.68, that’s all I want to pay.  I don’t want to pay $50 for $23 worth of gas, but I don’t really care what or where it lands as long as I know exactly what the charge was.  So in this case, we’re doing an analysis, we’re going to do an analytical weight.  
So first thing we are going to do, let me go back one, because I don’t, we’re going to analytically place some citric acid, we’re going to add phenolphthalein indicator, we’re going to analytically weigh some caustic soda and then we’re going to do a calculation.  And I left out my indicator, let me make sure I’ve got it.  You know the only thing that I had to bring with me was my phenolphthalein indicator and I thought how in the world am I going to get that through airport security.  I put it in my little zip lock bag with my toothpaste and so they never questioned my Visine coming through.  I just have to be careful not to put it in my eyes.  So you can get phenolphthalein also on Amazon, it isn’t expensive and the difference between good Amazon phenolphthalein and ones that get poor reviews is, the poor ones they leaked during shipping.  So if you look at the ratings you will know whether the people screw the lid on tight.  All right, so, we are going to place a disposable cup on the balance and press tare.  I use these little cups.  These are like bathroom size, disposable drinking cups.  I put it on the balance and I press the zero button.  So now this balance reads 0.00, and I’m going to add, I’ve got three spoons, and I don’t want to mix them up, one of them is going to be the citric acid spoon, one of them is going to be for stirring, and one of them is going to be for caustic soda.  So all I want now is about 10 grams of citric acid, and this citric acid is made by a little company, probably never heard of it, called Essential Depot, and the important thing about this is this is anhydrous citric acid.  Now this is important because the other kind won’t work.  This is important because the water if it isn’t anhydrous, water has some weight to it and I can’t remember, I don’t think I’ve talked yet about that.  Okay, disposable plastic cup, I’m going to weigh out 10-11 grams and notice I don’t care how much it is as long as I know what I got.  That’s 5.59, 6.33, 8.97, now I’m over 10, 10.41.  I don’t care that I went over because I have a credit card.  Okay, but I want you to record 10.41 grams of citric acid.  The next thing I need is some water.  I’m going to use distilled water because I don’t want to be fooled by any crap that might be hanging around in my drinking water.  I’m using a Pyrex mixing bowl here and I need about 500 mL, 2cups.  Notice I wasn’t all that careful, 500 mL, 2 cups, it doesn’t really matter, all I need is enough water so stuff is going to dissolve and that’s all I really care about.
Phyllis		Did you say you’re using distilled water?
KEVIN		Yes, distilled water and I’m using that because what if your tap water has a pH that’s higher or lower than a 7, so there’s nothing in this water that God didn’t give it and I’m not saying you have to use that for everything but if you care about the answer to this analysis, distilled water is what you want to use.  All right, so now I’ve got how much citric acid?  10.41 grams.  Okay, so what I should have done, I should have tared it at that point because now what I’m notice is this thing still has a little left in it.  In fact, it has .04 grams more than it had when I weighed the cup empty.  So 10.41 minus .04, 10.37.  10.37 is the amount of citric acid.  Now if I had my brain screwed on, I would have pressed the tare button before I dumped it, and then when I put it back on it would have read exactly 10.37.  All right now I need to get this dissolved, and now I’m going to add my indicator, phenolphthalein; one, two, three, four.  Again, it doesn’t really matter how much, you just want enough that when the color change comes, you want to see it.  Three to four drops, I said three drops, but I actually accidentally put in four drops, but that is not a catastrophe.  There is only two things that matter in this analysis.  One is the weight of citric acid, be very very careful about that, the other is the weight of caustic soda, which we’re about to get to next.  Okay, you’ll notice I weighed from the balance.  I have my little cup here and this actually reads a negative number now when I tared it and I dump it in, it now reads minus 10.37 grams.  It’s the citric acid that was there that isn’t there anymore.  Most of you weigh onto the balance am I right?  You put the thing on the scale and then you dump stuff into it.  There are some advantages on weighing from the balance.  Principally, uhhh, error, it is too heavy for this balance, you can’t put this on a balance like this, since this is a precision instrument, you don’t want to overload it.  The second thing is imagine I was making, we make a lot of single bars of soap, hundreds of them and we do it by weighing from the balance, because let’s say I want added my coconut oil da da da da, and I added my palm oil and I added my olive oil, “Oh crap, oh I just added too much olive oil.”  Have you ever done that, more than what you wanted?  If you weigh from the balance, you always know. Oh 7.6, 7.5, uh, there it is that’s my target, squirt.  You are never going to overshoot the mark if you’re weighing from the balance.  Because if you added coconut oil and palm oil and now you added too much olive oil, you can’t suck that olive oil out, it’s all mixed up already.   So there is a lot of really good advantages to weighing from the balance.  
All right, now we will talk about the materials, citric acid looks like this as a molecule and from this morning you can tell me exactly what kind of molecule this is.  Is it hydrophobic or hydrophilic?
Group		It’s hydrophilic.
KEVIN		It’s hydrophilic and how do you know that?  It’s red and white.  There are no water molecules here.  It fooled you right?  It looks like water, it’s red and white like water, but that is actually part of the citric acid molecule.  Underneath I give you the stick structures like what we would draw on a napkin.    The important thing are those OH’s and how many OH’s do you see?  There are four of them, four bright red atoms with four white hydrogen atoms attached to them.  They aren’t all equal, three of them are acidic and one of them is alcoholic.  I don’t mean meanies in rehab.  If you look at the stick structure, you will see there are two kinds of OH; there is one that is next to a double bond oxygen, those are the acidic ones and the one in the middle, the one that is sticking up is an OH that’s not connected to a carbon that’s got a double bond oxygen on it.  He’s merely alcoholic.  So as I look at this there are three acidic hydrogens that means how many molecules of sodium hydroxide does it take to react with citric acid?  There are three acidic hydrogens, it takes three hydroxides to react with those three acidic hydrogens.  Now that’s kind of cool because when we talked in the morning about oils, how many hydroxides go with each oil molecule?  Three to one.  It is the same thing here.  Three hydroxide ions go with one molecule of citric acid.   So there’s the equation underneath, H3 Cit + 3 NaOH gives me three Na3Cit + 3 H2O.  If you want a name for that Na3Cit, you would call it sodium citrate, exactly right and you can find sodium citrate as a chemical that people buy to use for things 
Group		Could it be a preservative?
KEVIN		It could be a preservative.  One thing about citric acid, like EDTA, citric acid will glum onto ions in solution, so for example if you are looking for something to sequester or to take calcium out of the equation, citric acid is something that will do that.  
All right, now we get to the anhydrous part.  We don’t care citric acid comes in two varieties.  There is anhydrous citric acid and citric acid monohydrate.  Monohydrate means what, one water.   All it means is that this is citric acid that is intimately bound up with one water molecule and both of them would do the analysis perfectly fine.  The difference is in weight.  The molecular weight of citric acid and monohydrate is bigger than then the molecular weight for anhydrous citric acid.  Good news is it is easy to determine what kind you have.  I look at the package. It says, “Finest quality granulated powder anhydrous, non GMO genetically modified organism product as used for an ingredient in making soap.  Bath salts, lotions and other skin care products”, and now you can add and for determining the percentage of NaOH and your caustic soda.  So this is the anhydrous version but I didn’t trust it because I thought well okay he says that, maybe it’s true, maybe it’s not true.  So the way to test it is weigh some out onto a piece of aluminum foil, stick it in an oven at 200º F for an hour and then weigh it again.  If it lost weight, the weight that it lost was water and that means it wasn’t anhydrous to begin with.  So not this bag, but the bag Derek sent me I did that with and I weighed it out and put it in the oven and I weighed it every 15 minutes for an hour and it lost exactly no weight.  He is breathing a sigh of relief over there.  It was the anhydrous citric acid which is exactly what you want.  If you have a 20 lb. sack of citric acid and monohydrate that you use for making bath salts, it is perfectly good for that.  You can convert it simply by sticking it in the oven at 200º F for an hour.  That will dry all the water off and you will be left with the anhydrous version.  You don’t need to do that for your bath salts, you don’t need to do it for your bombs, the only reason you are doing it is because you want to know when you weigh it out that 10.73 grams of citric acid, that it was citric acid and nothing else.  Okay, so that part is done.  Once it is dry, you don’t want it to get wet again.  So if you live in a humid area, you want to put the cap on it, keep it in a sealed container so it doesn’t absorb moisture from the air.  
I talked about phenolphthalein.  The color change starts at 8.2 and ends at 9.8, we’re going to see it going from colorless to bright pink.  We are going to keep our cups and spoons separate.  I used a cup for citric acid and I don’t want to use the same cup for my sodium hydroxide.   So that’s my citric acid cup to remind myself I’m going to stick it right there to the citric acid.  The spoons I’m also going to keep separate.  It’s not that it’s a danger thing, it’s that, you know what, that has little bits of citric acid on it.  I don’t want to contaminate my caustic soda that will fool me in to getting the wrong answer.  Okay, so we measured 500 mL or 2 cups of distilled water, we placed a disposable cup on the balance, we weighed out some anhydrous citric acid, we poured it in the measuring cup and stirred it up until it was completely dissolved.  Returned the cup to the balance and the weight that appears is the tare weight.  We record that and it is 10.37.  We added three, I actually added four drops of phenolphthalein. We are now going to go to a second disposable cup.  I’m going to press the zero or the tare button.  It now reads zero and now I’m going to open up a brand spanking new, never been opened bottle of Essential Depot caustic soda.  It’s reading 0.0 and I don’t care, I weighed out 10.51 grams, I don’t even care about that.  I’m pressing the zero button again on taring the balance.  It now reads 0.0.   Now the next thing that’s going to happen is I’m going to transfer sodium hydroxide into the mixing cup until the liquid turns pink.  It I do a 100th of a gram at a time for like 10 grams, that’s going to like take a 100 minutes.  I don’t want to do that.  I know that the answer is not going to be less than 6 grams, because I’ve done a calculation in advance and I will show you that calculation in a minute.  All I care about right now is I want to start the process and I’m not going to go slowly and carefully at the beginning.  I’m going to do like six grams of stuff.  There is 2.99, and it’s reading out a negative number here because remember I tared it, so it’s negative 5.40.  It’s now negative 6.32, crap, I went over.  Oh, you know what, it’s still right there, weighing from the balance 5.60, 5.85, 6.05, 6.02, 6.01, 6.00, I don’t really care that it’s 6.00, I just don’t want it to get it over.  Can you see the pink?  
Group		Yes, oh yeah.
KEVIN		So what happened is as the sodium hydroxide dissolved around each little granule of sodium hydroxide, the concentration was high and it turned pink, but then it got diluted throughout the solution and it came back down the citric acid, neutralized the sodium hydroxide and now I still got a transparent, clear solution.  From this point, I’m going to go slowly and carefully. 6.03 still clear, 6.09, 6.15 the tension is building, they will dub that over in the video, I’m sure, 6.21, 6.25, 6.28, 6.34 and what I’m seeing is there is like a little puddle of pink in there.  I know I’m getting close.  I don’t want to get carried away now, I’m going about as small as I can, 6.42, 6.46.  You can see if I had done that from the beginning, we would be here all day, 6.55.
Group		There we go
KEVIN		And I’m going to be careful because I can see that there is still see little bits down there that haven’t dissolved yet.  I’m being like super small now, 6.59
Group		Uh uh uh uh
KEVIN		And there it is and that was like as little caustic soda as I could get on my spoon.  I’m not going to be impatient because maybe that pink color is going to fade. Can everybody see that?
Group		Yeah
KEVIN		Okay.   That’s the end point.  So at this point I’m going to record 6.59.  What was the weight of citric acid?  10.37, and this is 6.59, write those two numbers down.  So that’s what we just did and now we’re going to do the calculation.  We’re going to take 10.37 that was the weight of the citric acid.  We’re going to divide it by 6.59 and multiply that by 62.46, so some of your phones will double as calculators, 62.46 x 10.37, divided by 6.59
Group		98.29
KEVIN		Let’s call it 98.30.  So the purity of it was 98.30 sodium hydroxide in caustic soda.  Is that good or bad?
Group		That’s pretty good
KEVIN		That’s pretty good.  What was the extra 2%?  The water, right?  Obviously it’s water.  Now how did it get to be 98, instead of 100?  And you don’t know where, right?  It could have come that way from the people that make it, it could have been introduced when Derek packaged it, and it could have been introduced in your own soap shop from leaving the sodium hydroxide opened to air.  Part of what motivated this was a dispute between Derek and a customer about they claimed he had sent her bad caustic soda.   And Derek is between a rock and a hard place.  He doesn’t know.  He doesn’t know what happened to that caustic soda once it left his warehouse.  And you don’t know when you get a bad batch of soap, what caused it.  Anybody ever have soap that turned out soft?  
Group		Oh yeah
KEVIN		Yeah and how do you know what caused that?  There’s lots of things, you could have made a mistake right, you could have measured out the wrong amount of something and you wound up with soft soap.  So here is a way that you can test your caustic soda.  It took us probably about 15 minutes and that’s with me explaining it the whole time.  So here’s a test that you can do on your own.  If you never have a problem, then you never have a problem, but if you want to protect yourself against it, whenever you order a new batch of caustic soda, if you get good at this measurement, you can test it as it arrives.  When you’re good at it you’ll have the test done in about 10 minutes and you will know when it arrived, what was the purity of the caustic soda.  If you wait until you have a problem, let’s say three weeks from now, you’re making soap, it turns out soft and you will say I remember Kevin told me how to do that, you do the test and it turns out to be 90% sodium hydroxide, how does that help you?  It does because now you know that your caustic soda is bad, right and that is the reason it turned out soft.  But it doesn’t help you to go back to Derek and say you sent me this crap caustic soda because he’s going to say and rightfully so, nobody else is complaining and how do I know that you didn’t leave the cap off the caustic soda and it absorbed moisture in your own soap shop.  If you test it coming in, and big companies do this all the time, it’s called quality assurance, they’re checking when they get a shipment from a supplier, they’re checking it to make sure it meets their own specifications.  It will cost you 10 grams of citric acid, 10 grams of caustic soda and you will have your answer in about 10 minutes. Is that worth it to you?
Phyllis		Absolutely
Question	On where did that number come from?
KEVIN		Good questions.  Ah, where did that number come from, I’m glad you asked that because I think it’s the next slide.  Oh there it is.  That’s the calculation, we are asking how many grams of sodium hydroxide are in 100 grams of caustic soda.  Why was the grams of caustic soda that I just weighed out and in other words it was the 6.59, 10.XX was the amount of citric acid, that I weighed out, that was 10.37.  I got 1 mol of H3Cit weighs 192.12, that’s the molecular weight of citric acid, that’s why we cared about it being anhydrous because that would be a different number for the monohydrate and we know it’s 3 moles of sodium hydroxide to one mole of citric acid.  Now you don’t have to understand the nuts and bolts of this calculation because I’ve done the arithmetic for you.   If you multiply all of those numbers out, except for the 10.XX that you’re going to weigh out and the 6.YY that you’re going to weigh out, all of the other numbers multiplied together to make 62.46.  What can you do about it?    If you catch it early you’re going to call your supplier and say “You know this caustic soda I just got in yesterday is only 80% sodium hydroxide,” and you will work it out with your dealer as to what to do about that.  Imagine that it’s your own damn fault.  You left the bottle open and crap and now I’ve got a bottle of caustic soda and I know it’s only 95% sodium hydroxide.  Is there anything to be done?  Well yeah I think there is.  Now you might think I’m just going to put it in the oven, right?  Well yeah, you can do that, but you need to heat your oven to 760º to drive the water out of caustic soda.  Most of you, I don’t think your oven goes that high.  So that’s not an option for most of us.  But if you know it’s only 95% and you know you need, I’m going to make up a number, you need 12 ounces of sodium hydroxide and you know that your caustic soda is only 95% sodium hydroxide, well you can do a calculation.  I want 16 ounces of sodium hydroxide, my caustic soda is 95%, I just divide by .95.  I know now that to get my 16 ounces of sodium hydroxide I need to weigh out 16.84 grams of caustic soda.   You’re going to feel nervous about that, because your lye calculator told you 16 ounces and you’re adding more than that.   You just have to say to yourself, “Yeah, but when I weigh out this caustic soda, the entire weight is not sodium hydroxide, some of it is water, and because I’ve done the test, I’m able to do the calculation and use this sodium hydroxide that has otherwise  been contaminated with water.”  All right, sorry it’s not the only containment, yeah.
Phyllis		Suppose you have caustic soda that’s been around for eight years.  I mean it’s still good right?
KEVIN		If it is sealed in the container and it’s air tight, it has a shelf life of millions of years and there is nothing really to go wrong with it.  The only thing that goes wrong with it is it absorbs moisture from the air.  So if you’re preventing that from happening, no reason the caustic soda wouldn’t have essentially an infinite shelf life.
Phyllis		Okay.
KEVIN		Okay.   There is a second contaminate though and that’s carbon dioxide.  Carbon dioxide is in the air.  There is more water than carbon dioxide in the air so the water is  your number one enemy, but carbon dioxide is also there, so in your eight year old caustic soda, its probably had time if the cap is leaky to absorb some carbon dioxide and there is nothing you can do about that.  You can’t, because you’re not going to be able to distinguish, it’s still going to have weight, you’re not going to be able to distinguish the carbon dioxide from the water using this test.  You can do a qualitative test though.  You can take your caustic soda, you can dissolve it 50/50 in water and the cool thing is sodium carbonate, that’s what the carbon dioxide turns in to, sodium carbonate is not soluble in 50% caustic soda, so it will float to the top, and you may have seen this.  Have you ever mixed up your lye and you see little crystals floating on the top?  That’s sodium carbonate.  Usually it’s only a little dusting and it’s happening right there, you can’t stop it because you’re breathing on it and the carbon dioxide is hitting the surface, happily combining with the sodium hydroxide and turning it into sodium carbonate.   But if you see like chunks and layers of that, then you know you got a large carbon dioxide contamination and you know it isn’t dangerous for making soap, it’s just that you don’t know how much of that white powder is actually still sodium hydroxide.   The best protection for you is to prevent it from happening in the first place.   Put the cap back on your caustic soda.  You don’t have to be paranoid, it’s not going to happen in like three seconds.  You don’t have to quickly, you know, top everything over because you’re in such a hurry, but don’t leave it off overnight.  When it’s convenient, put the cap back on your caustic soda whenever you use it.
Phyllis:		Suppose you have a small allergy, because I notice after a couple of batches, I started getting a little twitchy in the respiratory system.  
KEVIN		Is it from the fumes?
Someone	Wear a mask	
KEVIN		A mask is not going to protect, unless you’re using an OSHA mask that’s got filters in it and stuff.  Just a dust mask isn’t going to help you.  The very first thing is you need adequate ventilation.  So put an exhaust fan in your shop and turn it on, and make sure the exhaust fan is on the far side of your caustic soda.  So it’s pulling the fumes away from you instead of towards you.   The second thing you can do and the thing that we do is, we always mix it in a sealed bottle.  So most of you are mixing your lye in an open container like this, we use a polypropylene bottle and we add the caustic soda to the water, we screw the cap on and then we shake it up and that way there is no fumes because the thing is sealed; and it gets hot right?  So every once in a while, put it down, I open the top to let any pressure out that might have built up, screw the cap back on, shake it, shake it, and I don’t stop shaking until it’s all dissolved, because if I stop shaking, it will settle to the bottom and you will have a cake of undissolved material at the bottom and it is very hard to get that back into solution.
Someone	It also stops your carbon dioxide.
Kim		And it’s a good idea, I wrap it in a towel.  When I do that it keeps the lid covered because occasionally it will get so hot it will seep out of the lid, so I put a towel around it  and I always…
KEVIN		So if you are going to do it in a plastic container, you want polypropylene.  Normal plastic like this plastic, this is polystyrene, you don’t want that.  The plastic bottle there is polyethylene terephalate, you definitely don’t want to use that.   This is polyethylene, you don’t want that.  You want polypropylene and this might actually be polypropylene.  It will have a code on the bottom that will say “PP”, it’s polypropylene and the thing about it is it can withstand the temperatures that you get to when you dissolve caustic soda in water.  Yeah
Amanda	I have a question about the lye that you had sitting out earlier, do you still have that?
KEVIN:		Yep, it’s right down here.  Do you remember what the weight was?  13.85 was the first time, so this is the one we did early this morning.
Amanda	It was originally 13.76, then you weighed it and it was 13.85.
KEVIN		It is now 14.56.
Group		Wow
KEVIN		So just sitting out here in the air I’ve got a hydrometer here, it is 51% relative humidity in this room.  
Kim		Can you see any difference?
KEVIN		You can’t see any difference.   If you could notice anything, you’ll notice it doesn’t shake around as easily as it did before it’s clumped up, but it’s still a white powder and, you know, if I were just to grind this up, you wouldn’t be able to tell by looking at it that it was contaminated with water.
Phyllis:		Or, if you’re mixing a lot, you can always mix it with ice.
KEVIN		That’s another thing that people do.  If you’re doing it on a small scale like you guys are starting out, that’s fine, but imagine that you’re Vermont Soap Works and you make 700 lbs. of soap per day, ice would then be a significant expense for you and you’re probably not going to do that.  You probably are going to have a tank and I think soapequipment.com, don’t you have like a lye mixing tank, big stainless steel jobby, and when you get big, that’s the direction that you’re going to want to head, because you know from the business accounting stuff you’ve been hearing, everything that you have to buy contributes to the cost of your final product and that includes ice, you might not think about that as an expense.
I would like to do one more analysis if I have time.  So I would like to have one of you come up and do an analysis and we can either analyze the sample that we set out this morning we could do that, or I made up some fake samples by dribbling a little water into each one, so they are already artificially contaminated with water, and I will leave that up to the person who volunteers.  Who wants to do that?  And what I’m going to do is I’m going to ask you to use the little $26 jobby and we will see whether we can make that work.  Let me clean it up for you.  We need to rinse this out.  This stuff by now is just sodium citrate.  It can go right down the drain.    Okay, I’m going to talk you through it and we’re going to see.  Let’s time it, let’s see how long it takes, somebody with their phone can time it.  So first thing that we need is 500 mL of distilled water.   I don’t care if it’s 500 mL or whether it’s two cups.  Yep, start it now, yep.    Remember, that doesn’t matter, we just want enough and it doesn’t have to be a precision measurement.  Okay, so that’s good. We are going to weigh out some citric acid, we put this on the balance, press the tare button and it now reads 0.00.  We are going to use the citric acid spoon to load it up with 10. something grams.  And she hit 10.00 on the dot, we don’t even care, I’m not patting her on the head for that.  I don’t care what it is, as long as it is 10. something and now it’s 9.98.  Okay, so somebody is going to write that down, 9.98 grams of citric acid.  Press the tare button, it now reads 0.00, dump that in the water.  You don’t have to worry to get every last atom out of the cup because you are going to put it right back on there and it now read negative 9.96, that’s the actual amount of citric acid that went into the bowl, 9.96.   You can now cross out the previous 9.98, because that’s not the number that matters.  Okay, and it will jitter around a little bit because we’re moving around and there is air blowing and everything, 9.96.  Okay, stir it up, okay, we want three drops of Visine, I mean phenolphthalein, and some of you, and I guarantee, somebody’s going to go home and say, “Well I bought some Visine at the store and it didn’t work.”  Now this isn’t really 
Elsa		I’m going to call TSA and sa y be on the lookout for you
KEVIN		I should have known a stewardess in the audience I’m going to get in big trouble.  Okay stir it up and notice one thing that happened, the scale went off and that’s exactly what we’re dealing with here, so we need to be a little bit…  We need to do one more little thing.  We are now going to weigh out the caustic soda and you can pick any cup over there.  The one on the very end is the one we started this morning, but any of the others are perfectly good.  So normally I would press the tare button and I would weigh it out and see how far along I am, but I know the thing is likely to go off, so what I need to remember this number, 14.55.  That’s not the answer, that’s just the tare weight including the cup, okay?  So now you can press the tare button and you are going to use the caustic soda spoon and I want you to grab like six grams worth of material and that’s okay you can go ahead and dump that, there’s 2.17, you can keep going until you get to six.   Okay go ahead and dump that, that’s 5.87, that’s over, still too high, 6.8, almost there.  Okay, that’s fine, there we go and let’s go ahead and get all of that material.  What I’m going to do is, can you hold that, I don’t want to contaminate it because there is citric acid in there and I don’t want to stick that in my caustic soda and contaminate it.  But the point is not to clean the spoon, the point is that 5.92 includes every little bit of caustic soda on here, so stir it up.
Michelle	On the plane too?
KEVIN		I put this in my check baggage.   You’ll notice that it still got chunks of undissolved stuff there.  Okay, let’s see, okay that’s good.  Oh crap, don’t clean it because that stuff is important.  Even that stuff is included in that weight that we just used and look the scale shut itself off.  We would be screwed.  Except we wrote down 14.55.  I don’t even care about this at this point, I’m just going to go a little bit at a time, don’t even care about the scale, a little bit at a time, a little bit at a time, I’ll stir for you.  Each time like the littlest amount that you can actually see and get away with.   You will see that the pink comes and goes but as you get close, the pink will linger longer.  If you want to use that to scrape.  It is sticking to the spoon because of the humidity in the room.   
Question	How about a dehumidifier in your room.
KEVIN		You could, so you don’t necessarily need that in your whole shop, but if you had an air conditioned area that would be good.  Oh, yeah, yeah, yeah getting close.
Question	How much does it weigh now?
KEVIN		We don’t know because the scale turned off, that’s why we wrote down the 14.55.  That is so close, I can almost make myself believe that is pink.  Uh Uh Uh
Group		Uh 
KEVIN		No, No, No.  Scrape that back into the cup. All right, now the moment of truth comes.  So turn the scale on, don’t tare, it will come up to zero, 7.50.  7.50 is not yet the answer, I have to subtract 7.50 from the 14.55 that I had earlier.  The 14.55 included the cup.  It’s actually jumping around a little bit but 7.50, 7.49.  7.05, what was the weight of the citric acid?  It was 9.96.  So 7.05 divided 9.96 times 62.46, oh and also remember on the last one I had four drops of phenolphthalein.  There we go. Does that make you happy?   But it still from clear to pink it comes at the same place whether it’s dark pink or light pink.  Do we have an answer?
Amanda	88.24
KEVIN		88.24.  It goes down from 98 to 88, just by leaving it open from this morning.   
Phyllis		Do you think the drop made a difference in it?
KEVIN		No, it just made a difference how dark the pink was, it didn’t make a difference from being clear and being pink.  Does that make you happy?
Derek is always giving stuff away, awwww, (gives her the scale)
One more thing, here you go, here is the box.
So thanks a lot I hope this is useful to you and I will see you again.



click Forgot Password? below if your password does not work

Forgot Password?

Join Us

Password Reset
Please enter your e-mail address. You will receive a new password via e-mail.