How to use vinegar to harden your soap

[TeresaT]

So what is the difference in using salt instead of Sodium acetate or sodium lactate for making a harder bar of soap?

Two things. Mainly curiosity. I've been reading about salt bars (and have made some) and I know that salt bars are like bricks. You are better off making individual bars instead of a loaf because cutting the loaf can be a bear if you don't get it at that perfect moment. It will crumble and fall apart. But the second thing is label appeal. If I can get a hard bar that unmolds easily without using a "chemical" or listing sodium acetate or sodium lactate on the labels, people won't question "salt" as much as the others.

However, if the vinegar, does as good or better a job at hardening/unmolding/producing what I (personally) consider to be my "ideal" bar, then I'll just use vinegar. That will have a great label appeal because so many people associate Apple Cider Vinegar with good health and curative purposes. It's just a guessing game for me right now.

I've decided to use 100% olive oil and my standard 33.333% lye solution. I'll use no additives as a control, 2% salt, 2% sodium lactate, 100% vinegar as water replacement, 75% vinegar, 50% vinegar and finally 25% vinegar.

So basically, I have to get cracking and make seven batches of olive oil soap then take careful notes and chart all of their characteristics including hardness and unmoldability without appropriate scientific instruments and no science background. Easy!

I'm sitting here typing this laughing my butt off at the absurdity of that statement. But it's true. This is going to be so much fun. Well, I've got to get off my butt and get the soap stuff out. TOMH - I'm going to do 8 oz batches and use the individual molds that I have. I'll add a colorant to each type so I don't get them confused. I've got micas and oxides. I hope that doesn't mess up the results.

 

[topofmurrayhill]

I've decided to use 100% olive oil and my standard 33.333% lye solution. I'll use no additives as a control, 2% salt, 2% sodium lactate, 100% vinegar as water replacement, 75% vinegar, 50% vinegar and finally 25% vinegar.

Sounds exciting. If you want penetrometer readings, send over a chunk of each.

 

[TeresaT]

Sounds exciting. If you want penetrometer readings, send over a chunk of each.

I will do that. Thanks!

 

[snappyllama]

Thanks again for this thread and taking the time to answer my questions (as well as other folks with illuminating questions of their own)... It's definitely something I'll consider when my vat of SL starts looking low. I

 

[biarine]

Wow interesting I never good in math

 

[cmzaha]

I wouldn't go masterbatching until we have more experience with this technique. At least you should make some small solutions and sit them on a shelf for a while to see what happens. But yes I would think you could do it if you're willing to do some more figuring and experimentation. Vinegar is only 95% water plus the H2O produced in the chemical reaction. You'd have to account for this when considering a 50% concentration. We also don't know how the sodium acetate affects how much NaOH it will be possible to dissolve.

Another issue with larger scale production is that we don't know much about nature of the water used to make vinegar. Might be a good idea to use EDTA until we can find out if the water is distilled or just purified tap water or whatever.

All good points. I did think of the 95% water factor. Just might make up a small master batch and let it sit. Let me know if I am off kilter here. I was going to add in the 5% water difference with distilled to bring up the full 50% water, then add in the extra lye. I was also considering if the NaOH would completely dissolve. Will try a little later and see what happens. Instead of EDTA is use the Citric Acid method only because I always have a lot of citric acid around. I also make it up into a 50/50 solution.

Since I am making veggie soaps tonight I just made up my lye using your instructions targeting 2%. LOL, will probably come out like a rock since I have 40% palm. Thinking I better watch cutting time

 

[cmzaha]

Two things. Mainly curiosity. I've been reading about salt bars (and have made some) and I know that salt bars are like bricks. You are better off making individual bars instead of a loaf because cutting the loaf can be a bear if you don't get it at that perfect moment. It will crumble and fall apart. But the second thing is label appeal. If I can get a hard bar that unmolds easily without using a "chemical" or listing sodium acetate or sodium lactate on the labels, people won't question "salt" as much as the others.

However, if the vinegar, does as good or better a job at hardening/unmolding/producing what I (personally) consider to be my "ideal" bar, then I'll just use vinegar. That will have a great label appeal because so many people associate Apple Cider Vinegar with good health and curative purposes. It's just a guessing game for me right now.

I've decided to use 100% olive oil and my standard 33.333% lye solution. I'll use no additives as a control, 2% salt, 2% sodium lactate, 100% vinegar as water replacement, 75% vinegar, 50% vinegar and finally 25% vinegar.

So basically, I have to get cracking and make seven batches of olive oil soap then take careful notes and chart all of their characteristics including hardness and unmoldability without appropriate scientific instruments and no science background. Easy!

I'm sitting here typing this laughing my butt off at the absurdity of that statement. But it's true. This is going to be so much fun. Well, I've got to get off my butt and get the soap stuff out. TOMH - I'm going to do 8 oz batches and use the individual molds that I have. I'll add a colorant to each type so I don't get them confused. I've got micas and oxides. I hope that doesn't mess up the results.

Can't wait to hear the results. Will be interesting to see if it makes any difference with the slime/snot/gel of castile after a nice long cure

 

[ngian]

Multiply your oil amount by the percentage you chose:
2% of 500 g oil is 500 x .02 = 10 g sodium acetate (SA) desired

Multiply the SA amount by 14.6 for the amount of water to replace with vinegar:
10 * 14.6 = 146 g vinegar

Multiply the SA amount by .49 for the amount of extra NaOH to add to what your lye calculator told you:
10 x .49 = 4.9 g extra NaOH

That's all there is to it.

If you happen to want to replace ALL your water with vinegar, multiply your liquid amount by .0335 to get the amount of extra NaOH to add.

Thank you very much TOMH for your simplified version and I wanted to ask you if you can tell me what would be the numbers for vinegar with 6% acetic acid as this is the % we have in vinegars in the Greek market.
If you can tell me your first name also I could credit you for this procedure in a Greek fb group.

Thank you in advance
Nikos

 

[penelopejane]

Can't wait to hear the results. Will be interesting to see if it makes any difference with the slime/snot/gel of castile after a nice long cure

If it reacts the same way as salt it will. I make 100% OO soap with 25-50% salt and they are lovely - hard and white, no snot. Mine weep for a fair while. Their weeping slows a lot but my last one (haven't got my notes with me so mad 6 months old) is still slightly damp - so slowly weeping.

 

[topofmurrayhill]

Thank you very much TOMH for your simplified version and I wanted to ask you if you can tell me what would be the numbers for vinegar with 6% acetic acid as this is the % we have in vinegars in the Greek market.
If you can tell me your first name also I could credit you for this procedure in a Greek fb group.

Thank you in advance
Nikos

For 6% vinegar you can multiply by 12.2 (or 12.17) instead of 14.6.

 

[TeresaT]

When you use vinegar to replace some or all of your water, the acetic acid in the vinegar reacts with sodium hydroxide to form sodium acetate. Sodium acetate works like sodium lactate to harden your soap, except all you have to buy is vinegar.

I promised simpler instructions for folks who don't want to get so exacting with the math. I have done this technique with white vinegar, but the instructions will work with any vinegar that contains 5% acetic acid.

First decide how much sodium acetate you want in the soap. Try maybe 1 or 2% of the oil amount for your first time out. Lets say 2% for the example.

Multiply your oil amount by the percentage you chose:
2% of 500 g oil is 500 x .02 = 10 g sodium acetate (SA) desired

Multiply the SA amount by 14.6 for the amount of water to replace with vinegar:
10 * 14.6 = 146 g vinegar

Multiply the SA amount by .49 for the amount of extra NaOH to add to what your lye calculator told you:
10 x .49 = 4.9 g extra NaOH

That's all there is to it.

If you happen to want to replace ALL your water with vinegar, multiply your liquid amount by .0335 to get the amount of extra NaOH to add.

The more exacting explanation of the math, for those who want it, is here:

http://www.soapmakingforum.com/showthread.php?t=57991

I have just discovered this does not work if you use a 33.333% lye solution.

My weights in grams are:
Water: 260.69
NaOH: 130.34
Oils: 1000.00

So, the 2% SA would be 20 gms (1000 * .02). I would need 292 gms vinegar (20 * 14.6) and 9.8 gms NaOH (20 * .49). That would be 32 gm too much liquid.

I originally started doing the math with my two pound batch recipe. Which is only 907.18 grams of oils. (Ya see where I'm going with this?) I got these numbers:
Water: 244.20
NaOH: 122.10
Oils: 907.18

SA @ 2% = 18.14. Check. Vinegar = 264.844. Chec WHAT? How is that possible. OK. Wait, maybe the SA's not right. .02 X 907 = 18.14. OK, I got that again. So I multiply 14.6 by 18.14 for vinegar? Wait. Let me round this up to 1000 grams. That will make this right. This can't be right. :evil: Man, I really suck at math. :sick: OK. So 1000 time 2% equals 20...

Yep. After a few times I realized no matter how many times I sliced it, I didn't suck at math that much. When you use a 2:1 water:lye solution and you want to do a 2% sodium acetate solution, just ignore the formula and multiply your water amount by 0.0335 and be done with it. Or ignore it completely and have a "mystery" SF.

I am going to have some Jamoca Fudge Almond ice cream. I have earned it. My brain hurts.

 

[topofmurrayhill]

Yep. After a few times I realized no matter how many times I sliced it, I didn't suck at math that much. When you use a 2:1 water:lye solution and you want to do a 2% sodium acetate solution, just ignore the formula and multiply your water amount by 0.0335 and be done with it. Or ignore it completely and have a "mystery" SF.

I hope that you enjoyed your ice cream and that the throbbing has subsided. No, your math doesn't suck. Let me tell you why on the one hand you are completely right, and on the other hand it works better with a 33% lye concentration than you suspect.

When you use a 33% like concentration, the amount of water you can replace ends up giving you more or less 2% SA. I plugged 30% CO, 40% PO and 30% OO into Soapcalc as an example, and the amount of vinegar for 2% SA was almost exactly the water amount. In your scenario, you didn't even have enough water to replace.

HOWEVER, this bring us to one of the ways that I simplified the instructions. When we talk about using some percentage of sodium LACTATE, we are talking about a 60% solution because that's the way it's usually sold. That means that 2% sodium lactate is actually 60% of 2 = 1.2% solid SL and the rest is water. The usual terminology is that it's 1.2% on a dry matter basis.

My original instructions took this into account but it confused people so I didn't include it above. The bottom line is that to make the amount comparable what people call 2% SL, you actually only need 1.2%, meaning 12 g SA rather than 20. That will fit comfortably into your water amount.

So here is some more guidance. If the recommendation for SL is to use 1% to 3% of 60% SL solution, the dry matter amount is actually 0.6% to 1.8%. If you want to use an equivalent amount of SA, those are the percentages you should calculate with.

The 2% you were calculating is equivalent to 3.33% SL solution. You don't need that much.

 

[Steve85569]

I did run a batch of soap today using the .0335 multiplier since I simply replaced all the water with vinegar. The soap calc'd out to a hardness of 30 with a cleansing value of 6 and conditioning at 65. Made the soap this morning and just finished cutting it. WOW!!! This unmolded three ( yes three) days faster than the last attempt at this without the vinegar. Sweet!!!

I know it never happened without pictures so I'll get some posted in the morning.

Next I'll try a soleseife' with the vinegar before adding the lye. I'm thinking a light brine of 10% salt just to see if it will stay in solution during the reaction between the vinegar and lye.

Colors will be changed to protect the absent minded from confusing the batches. I'll also use a different FO.

 

[TeresaT]

Thanks, TOMH! That makes sense. (Of course, I had to read it a few times. Slowly.)

Steve...awesome news! This whole vinegar thing is like magic! And since you mentioned salt...

You know those experiments I was doing Saturday with hardening agents and 8 oz of olive oil? Yeah. I unmolded everything Sunday. The salt batch didn't fare well. In fact, when I unmolded it, the loaf broke in half. I waited a couple of hours and then sliced it. It was still pretty soft; however, it was olive oil. Olive oil takes forever to harden up, right? I did a zap test and it didn't zap. When I wiped the cutter off I decided to wash my hands with the soft soap to see if there was any kind of lather at all or just slime. I have chemical burns on my hands. Apparently, salt reduces the saponification rate of olive oil. By. A. LOT. That was a majorly stupid thing to do; in the back of my mind, a tiny voice was saying, "This isn't a good idea." (Even though it didn't zap. I had never had smooshy soap before.) I didn't feel the burn at first. I was washing my hands for probably 15 or 20 seconds before I felt the burn. Fortunately, the water was running and I didn't have it really hot, I was able to slam the "gear shift" to the right with my elbow and flood my hands with the cold water. The interesting thing is that's a new faucet. My old faucet was the twisty kind and I wouldn't have been able to switch to cold so quickly. I've only had this faucet for about two weeks. I have ugly old-lady hands to begin with, but this made them even worse. They're feeling a lot better today and aren't so red, but they definitely are still raw looking. I'll have to see if I can get a photo of today's lovely look.

 

[ngian]

It was still pretty soft; however, it was olive oil. Olive oil takes forever to harden up, right? I did a zap test and it didn't zap. When I wiped the cutter off I decided to wash my hands with the soft soap to see if there was any kind of lather at all or just slime. I have chemical burns on my hands. Apparently, salt reduces the saponification rate of olive oil.

What was the lye concentration for the castile? How hot did you mix? Did it pass the gel phase?

The above can affect the speed of saponification and the time at which you can cut the soap loaf without any problem.

 

[topofmurrayhill]

I was washing my hands for probably 15 or 20 seconds before I felt the burn. Fortunately, the water was running and I didn't have it really hot, I was able to slam the "gear shift" to the right with my elbow and flood my hands with the cold water. The interesting thing is that's a new faucet. My old faucet was the twisty kind and I wouldn't have been able to switch to cold so quickly. I've only had this faucet for about two weeks. I have ugly old-lady hands to begin with, but this made them even worse. They're feeling a lot better today and aren't so red, but they definitely are still raw looking. I'll have to see if I can get a photo of today's lovely look.

Ouch.

At least it wasn't math that got you.

 

[TeresaT]

What was the lye concentration for the castile? How hot did you mix? Did it pass the gel phase?

The above can affect the speed of saponification and the time at which you can cut the soap loaf without any problem.

And this is why a non-scientist should not be testing stuff! I don't take temps. I soap at room temperature. Lye concentration was 33.333% (I always soap at 2:1 concentration). I added 2% salt to the water & fully dissolved it before I added the lye. I let the lye cool down to "warm to the touch" temperature before I mixed it with the oil. SBd until it was pudding and poured it into the mold. This was the second batch I did, so it was in the mold by 10:15 Saturday night. I didn't cover any of the molds with plastic (they're ashy), but once all of the tests were made, I put them in the cold oven. That was around 12:30 AM Sunday morning and I unmolded 4:30 PM Sunday night. I didn't cut & burn my hands until around 6:30 PM. The interesting thing (to me, anyway) is this was the only one that was like that. The control batch, which I did first around 9:40 PM, was fully saponified and rock solid when I unmolded it. The salt was mush. I would have thought the one with nothing in it would have been the softest after just 18 hrs in the mold. I'll have to look at the notes from last night to get a better idea of what the soaps felt like. The sodium lactate batch was actually softer than the control. I don't know if that has to do with the fact that they were in different molds made with different silicone or not.

 

[topofmurrayhill]

And this is why a non-scientist should not be testing stuff! I don't take temps. I soap at room temperature. Lye concentration was 33.333% (I always soap at 2:1 concentration). I added 2% salt to the water & fully dissolved it before I added the lye.

Not to complicate matters, but there are a few different things that could cause these additives to have different effects. Let's consider one of them.

How do we know that the usage rates we are testing are at all comparable? Maybe you only need half as much of one additive to get the same effect as another. If instead you put in equal amounts, you don't end up with a meaningful comparison.

So how can we possibly guess what the comparable usage rates might be? Actually there are 2 things you would probably try off the bat. One of them is to use equal percentages by weight as you tried to do. The other is to use equal molar amounts -- which means we try using the same number of molecules instead of the same weight. That would affect the usage rates like so:

Sodium lactate 2%
Sodium acetate 1.5%
Sodium chloride 1%

An SL molecule weighs twice as much as a salt molecule. To add the same number of molecules of each, our salt weight will be half the SL weight. If SL is 2% by weight, the same molar amount of salt is half, or 1% by weight.

 

[Steve85569]

It was still pretty soft; however, it was olive oil. Olive oil takes forever to harden up, right? I did a zap test and it didn't zap. When I wiped the cutter off I decided to wash my hands with the soft soap to see if there was any kind of lather at all or just slime. I have chemical burns on my hands. Apparently, salt reduces the saponification rate of olive oil. By. A. LOT. That was a majorly stupid thing to do; in the back of my mind, a tiny voice was saying, "This isn't a good idea." (Even though it didn't zap. I had never had smooshy soap before.) I didn't feel the burn at first. .

Ouch!!
Never, ever wash your hands with a soap that hasn't set. You got lucky.
I used to work with commercial quantities of lye cleaning things to bare metal. If you hands start to feel the least bit slick you are headed for trouble there. With the soap you can't feel the slick that lye produces when it starts turning YOU in to - soap.

I have a vinegar / salt / lye mixture cooling now. I have noticed some precipitate so I'll be sure and stir the mixture until everything is in suspension before adding to the oils. I will probably gel this overnight so I won't be even checking on it for 12 hours after I make it. If it isn't firm enough to unmold I won't. I have more time than I have good sense so I can wait.

TT - your burns will turn to a rash looking scab before they heal completely if I remember correctly. They will be sensitive for several weeks too. I'm very glad it wasn't worse. Be careful please!!!

Steve

 

[TeresaT]

Not to complicate matters, but there are a few different things that could cause these additives to have different effects. Let's consider one of them.

How do we know that the usage rates we are testing are at all comparable? Maybe you only need half as much of one additive to get the same effect as another. If instead you put in equal amounts, you don't end up with a meaningful comparison.

So how can we possibly guess what the comparable usage rates might be? Actually there are 2 things you would probably try off the bat. One of them is to use equal percentages by weight as you tried to do. The other is to use equal molar amounts -- which means we try using the same number of molecules instead of the same weight. That would affect the usage rates like so:

Sodium lactate 2%
Sodium acetate 1.5%
Sodium chloride 1%

An SL molecule weighs twice as much as a salt molecule. To add the same number of molecules of each, our salt weight will be half the SL weight. If SL is 2% by weight, the same molar amount of salt is half, or 1% by weight.

Hmmmm. I've got the 2% sodium lactate already. That's colored with ultramarine violet oxide. The 2% sodium chloride is still crappy. It's colored with green oxide. It has the consistency of wet chalk or semi-dried spackle. I can make a new batch tonight with 1% sodium chloride and see how that fairs tomorrow after work. Since I made four different vinegar batches, one of them is bound to have 1.5% sodium acetate in it.

However, I think I will try new batches this weekend. I think I'm going to make the solutions ahead of time and leave them in labeled jars on the counter. This way, all of the solutions will be at the same "room temperature" when I dump them into the "room temperature" olive oil.

Since I suck at math, will you tell me how much 5% acidity apple cider vinegar I need to mix with how much distilled water to make a 33.333% lye solution that will give me the needed 1.5% sodium acetate to saponify 8 oz olive oil with a 5% SF according to SoapCalc.

I just checked the jug from Soaper's Choice and my SL has "sodium lactate/60" on it. So, when making the solution for the SL, I just use 2% of the 8 oz, which ends up being 4.536 gm (I'll round to 5). No funky math for that, right?

The salt will be simple, 2.268 gm, rounded down to 2 gm.

I still don't understand why the salt was an epic fail though. I used Morton's canning and pickling salt. It's pure salt. No additives like iodine or anti-caking agents. In fact, it's quite a brick. I had to bang it on the counter to get it into the container.