Meaning of Longevity

ackemp

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Feb 9, 2020
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Hi guys. Does 'Longevity' in the results section of the soap calculator mean that you won't get so many washes out of each bar, or that the oils will go off sooner? If the latter, will the addition of Rosemary Extract help?
 
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Yooper

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No, it doesn’t mean it will go off sooner. It means how long the bar will last in normal use, and and is based on the solubility of the soap.
The number comes from Subtracting the cleansing value from the hardness Value.
Some soaps, like pure castile (100% olive oil soaps) will be hard enough to pound nails with after a long cure- but will not last as long in the shower due to its higher solubility.
 

ackemp

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Feb 9, 2020
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No, it doesn’t mean it will go off sooner. It means how long the bar will last in normal use, and and is based on the solubility of the soap.
The number comes from Subtracting the cleansing value from the hardness Value.
Some soaps, like pure castile (100% olive oil soaps) will be hard enough to pound nails with after a long cure- but will not last as long in the shower due to its higher solubility.
Thanks for your response. Can anything be added to counteract the lack of longevity?
 

Yooper

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Yes- using harder oils/butters will add to the longevity.
Adding beeswax will also help (but not too much- it will get sticky if you add too much).
Adding stearic acid to the batch will also make it harder, meaning it would be longer lasting. That’s commonly used in shaving soap.
Curing the soap longer before first use will mean a longer lasting bar also, since more water would have been evaporated out.
Table salt and sodium lactate would also help. Not much table salt at all- I forget how much is the recommended use, but you’d want the non-iodized small grain table salt.
 

ackemp

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Feb 9, 2020
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Thanks so much for your advice, it's much appreciated. I am trying to create hemp soaps which are also vegan. I've worked out a recipe but the only problem is longevity, so I will now look at the additives you mention above to counteract this shortcoming. Thanks again. Love the website and recipe builder btw :)
 

Rsapienza35

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Nov 5, 2019
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Thanks so much for your advice, it's much appreciated. I am trying to create hemp soaps which are also vegan. I've worked out a recipe but the only problem is longevity, so I will now look at the additives you mention above to counteract this shortcoming. Thanks again. Love the website and recipe builder btw :)
While salt may make a harder bar, it is only for the purpose of unmolding. Hardness and longevity are not the same. You want oils high in stearic and pamitic. I thought beeswax did not contribute to longevity, but I could be wrong. I have never used it.
 

Sherrill

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Mar 24, 2020
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I have also been wondering about this. I've tried a number of recipes through the calculator (which I love!), and every element has been well within the recommendations except Longevity. My longevity number has been in the red every time! I'm a novice soaper.
 

Yooper

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Upper Peninsula of Michigan/ Florida Gulf Coast
I have also been wondering about this. I've tried a number of recipes through the calculator (which I love!), and every element has been well within the recommendations except Longevity. My longevity number has been in the red every time! I'm a novice soaper.
It's often ok to have it in the red, if everything else is ok.
As an example, most people will tell you to not make a coconut oil soap with more than 20-30%, and to not superfat over about 5-7% if you want to keep the chances of rancidity lower.

But my salt bar is 100% coconut oil, with 20% superfat! And take a look at my "red":
28
Still, it makes an awesome soap.
Remember that software is very helpful, especially with calculating the lye. But it's only a help.

If you are a novice soaper, you can either use trusted recipes (but always always run it through the calculator to ensure the lye measurement is right!) or even post it on the forum to see what the others with experience have to say about it.
 
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