Glycerin and lard questions

Does anyone know of a list that gives the amount of glycerin produced by individual oils?

Does lard provide bubbles? I ask this because I made the same recipe twice, but with different containers of lard and got very different lather. (The only other difference was the nice lathering bar had fragrance oil, the disappointing bar had lavender eo. Maybe lard differs from animal to animal...explaining the difference in lather?

The lather from lard is a creamy lather not bubbly. The only difference I can think of with the FO is that it may have contained some type of sugar or honey. Sugar is known to help with bubbles.'

Also lather will usually improve with the age of the bar.

You're better off to look at the lye required to get a quick and easy answer about the amount of glycerin produced. Here is something I wrote up awhile back and maybe it will answer your question --

About 0.77 gram glycerin is produced for every 1 gram of NaOH used.

Overall, most soaps will average 10-11% glycerin by weight based on the weight of the oils in the recipe. Soaps made with mostly fats that have a high saponification value -- all or mostly coconut oil, palm kernel oil, etc. -- can have up to 14% glycerin on an oil-weight basis.

Example: A recipe calls for 1000 g of a mixture of oils; the soap made from that recipe will most likely contain 100-110 g glycerin. Divide that number by your total recipe weight (fats + water + lye + additives) to get the overall percentage of glycerin in the finished soap as it comes out of the mold.

As the soap cures and loses weight due to moisture loss, the % of glycerin goes up. Here's another example based on one of my typical recipes: The soap bars at the time they're cut would contain about 7% glycerin by weight. After curing for a month and losing some water weight, the glycerin content in the bars would be around 8.5% by weight.

and re the lard question: if you are using commercial lard, it is the product of more than one animal (many more) per container.

DeeAnna said:

About 0.77 gram glycerin is produced for every 1 gram of NaOH used.

Overall, most soaps will average 10-11% glycerin by weight based on the weight of the oils in the recipe. Soaps made with mostly fats that have a high saponification value -- all or mostly coconut oil, palm kernel oil, etc. -- can have up to 14% glycerin on an oil-weight basis.

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Just wondered about that some time ago...
Could you reveal the source please? TIA

"...Could you reveal the source please?..."

Um.... No outside source was required, Eucalypta. I just got my geek on, found a calculator and pencil, and dusted off my math and chemistry skills. :crazy:

I'm not sayin' I never mistakes or never get things wrong -- my dear husband can tell you otherwise!!! -- but I used to do this kind of thing for a living as a college instructor and as an engineer, so it comes pretty easy to me.

Even with the mistake the number is high) I love it. It seems that I have wonderful soaps

Mistake? I'm not sure what you're referring to, Dahlia. Clarify, please?

DeeAnna said:

"...Could you reveal the source please?..."

Um.... No outside source was required, Eucalypta. I just got my geek on, found a calculator and pencil, and dusted off my math and chemistry skills. :crazy:

I'm not sayin' I never mistakes or never get things wrong -- my dear husband can tell you otherwise!!! -- but I used to do this kind of thing for a living as a college instructor and as an engineer, so it comes pretty easy to me.

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Right!
Let's shake hands then. I used to teach math and information and communication technology in college. Although I like chemistry too, I hoped for a reference table ... but I'll manage.

I know that in manufactured soapmaking the glycerin is lost in the process and later added again. (You know those commercials "soap with extra added glycerin" yeah... snake oil.) How much in % I couldn't find out yet.

Well I hope you'll keep the disputes with your DH to a minimum, we all make mistakes sometimes. My XDH teaches art, which leads to another nature of discussions.

I'm really confused. I made what was obviously a misunderstood joke about myself that I am not always right. I did not mean that to imply my numbers were wrong, however.

The weight of glycerin produced based on the fats in the recipe will vary with the saponification value of the fats, the percentages of the fats, and the actual superfat. Since there are infinite number of fat and superfat combinations, there are an infinite number of solutions to that problem. One can create a spreadsheet to calculate the answer, but it doesn't translate into a tidy table.

Here's the math behind my numbers, for the record.

Fact: NaOH = 39.997 g/mol
Fact: Glycerol (glycerin, C3H8O3) = 92.09382 g/mol

Fact: In saponification of triacylglycerides, 3 molecules (mols) of NaOH are required to make 3 molecules (mols) of soap and 1 molecule (mol) of glycerol. So the molecular ratio of glycerol to NaOH is 1:3.

(1 mol glycerol / 3 mol NaOH) x (92.09382 g glycerol / mol) x (mol / 39.997 g NaOH) = 0.7675 g glycerol / 1 g NaOH

That is the math and chemistry behind my previous number of 0.77 grams glycerin produced by saponification for every 1 gram of NaOH.

The relationship between NaOH and glycerin produced is a tidy, simple solution. It will work regardless of the amount and type of fats in the recipe. It is totally independent of the amount of superfat in the recipe as well. The only time when this relationship won't work is with a lye heavy recipe.

Moving on. Here's a simple, classic recipe:

olive oil 70 g
coconut oil 30 g
superfat 5%
28% lye solution concentration

My personal soap recipe calculator figured these weights for lye and water for this recipe:

NaOH 14.6 g
Water 37.7 g

Total batter weight = 30 + 70 + 14.6 + 37.7 = 152.3 g

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Glycerin made by saponification (see previous post) = 14.6 g NaOH * (0.77 g glycerin / g NaOH) = 11.2 g glycerin

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edit: For this recipe, the glycerin based on the weight of the oils in the recipe would be:

% glycerin, oil basis = 11.2 g glycerin / 100 g oil * 100% = 11.2% glycerin by weight of oil

***

For those who want to know the % glycerin in the soap, here are your answers:

% glycerin in fresh soap = 11.2 g glycerin / 152.3 g batter * 100% = 7.4% glycerin in fresh soap

Soap loses roughly 10% to 15% of its weight during cure. Assume a 10% loss, or a total weight loss of 15.2 g for this particular recipe. No glycerin is lost ... just water ... so the glycerin made by saponification (11.2 g) doesn't change during cure.

% glycerin in cured soap = 11.2 g glycerin / (152.3-15.2) g * 100% = 8.2% glycerin in cured soap

The glycerin % in the soap goes UP during cure, because the total batch weight goes DOWN during cure.

***

I stated in my first post that, "Overall, most soaps will average 10-11% glycerin by weight based on the weight of the oils in the recipe. Soaps made with mostly fats that have a high saponification value -- all or mostly coconut oil, palm kernel oil, etc. -- can have up to 14% glycerin on an oil-weight basis."

edit: I stand by my numbers, folks.

glycerin isn't lost in the processing, it's removed and sold as a separate profit-generating product, iirc.

PS *I* knew what you meant with your joke, DeeAnna

"...I know that in manufactured soapmaking the glycerin is lost in the process and later added again. (You know those commercials "soap with extra added glycerin" yeah... snake oil.) How much in % I couldn't find out yet...."

You can add more glycerin to commercial soap than is naturally produced, so knowing the natural production of glycerin during saponification is honestly a moot issue. CanaDawn is right that glycerin recovered from commercial soap is sold as a byproduct, although bio diesel production is generating a lot of glycerin as well and is glutting the marketplace.

The other thing that most people don't realize is that most commercial soap not only has very little or no glycerin unless it has been deliberately added to the formulation, but the soap is also is formulated to have a zero to very slightly positive (under 1%) superfat.

DeeAnna said:

The other thing that most people don't realize is that most commercial soap not only has very little or no glycerin unless it has been deliberately added to the formulation, but the soap is also is formulated to have a zero to very slightly positive (under 1%) superfat.

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Which is why "with added glycerin" is such a red herring....it's just replacing what was taken out from the natural reaction in the first place.

OMG DeeAnna! Thank you so much for another chemistry session! Learned so much about glycerin today!
Where do I need to pay for the chemistry tutoring fee :mrgreen:?

Thank you for your time!

Big hug

Dorymae said:

The lather from lard is a creamy lather not bubbly. The only difference I can think of with the FO is that it may have contained some type of sugar or honey. Sugar is known to help with bubbles.'

Also lather will usually improve with the age of the bar.

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That's an interesting possibility, never knew fo's might contain sugar.

DeeAnna, thanks for letting your geek out. I'm trying to formulate soap with the highest glycerin levels to have ready for winter.

DeeAnna said:

"...I know that in manufactured soapmaking the glycerin is lost in the process and later added again. (You know those commercials "soap with extra added glycerin" yeah... snake oil.) How much in % I couldn't find out yet...."
Bad wording...

You can add more glycerin to commercial soap than is naturally produced, so knowing the natural production of glycerin during saponification is honestly a moot issue.
CanaDawn is right that glycerin recovered from commercial soap is sold as a byproduct, although bio diesel production is generating a lot of glycerin as well and is glutting the marketplace.

Yep, I'm aware of that - it is exactly what I meant.

The other thing that most people don't realize is that most commercial soap not only has very little or no glycerin unless it has been deliberately added to the formulation, exactly my point. but the soap is also is formulated to have a zero to very slightly positive (under 1%) superfat. Makes sense 2me.

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English isn't my first language: by "lost" I meant "lost for the soap".
It was way past bedtime here and I didn't feel like looking up the correct syntax for the "salting-out process" ...
(Turned out that I could have guessed it.)

CanaDawn said:

Which is why "with added glycerin" is such a red herring....it's just replacing what was taken out from the natural reaction in the first place.

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We're all on the same page here.
Just bad choice of words on my part.

@DeeAnna
Thank you so much for the glycerin calculation!
You're a hero.

I thought /i/ liked math Deeann has me beat