Longevity of soap

lingaylew66

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Mar 1, 2021
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How do I increase the longevity number of my soaps? All the recipes that I come up with have a low number on longevity.
 

angelaperkinson

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Apr 15, 2021
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I've just switched to this calculator today after using another one for years because of the ability to calculate my lye solution masterbatch. While transferring all of my tried and true recipes I noticed almost all of my "longevity" numbers are low. 😑 Even on my harder bars.
 

Yooper

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Sep 7, 2019
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Upper Peninsula of Michigan/ Florida Gulf Coast
The numbers should be just about the same, if the ingredients are the same. Can you post a recipe screenshot from both calculators, so I can take a look? BTW, ‘harder’ doesn’t mean always longevity unless it comes from solid oils- you could pound nails with an aged 100% olive oil bar, but it’ll melt fast in the shower. That is a generalization, but not always true.
 

TriniKellKells

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Jun 23, 2021
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In general, “harder” soaps have longer longevity. Oils that are solid at room temperature are considered hard oils- coconut oil, tallow, lard, shea butter, etc.
I need someone to explain ... like really break it down for me. I would get high numbers for "Hardness" but low numbers for "Longevity".
 

ChemicalPyros

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Nov 4, 2019
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Lebanon
I need someone to explain ... like really break it down for me. I would get high numbers for "Hardness" but low numbers for "Longevity".

Longevity and Hardness are usually wrongly correlated, they each correlate with the fatty acid profile of a soap (if you are making a very basic soap of oils and lye and water), but they start to differ the moment you start adding other additives from EOs to FOs to clays and powders so on and so forth.
In summary, the hardness correlates to the amount of Lauric Acid, Myristic Acid, Palmitic Acid, Stearic Acid and other saturated fatty acids.
Longevity on the other hand correlates with Lauric Acid, Stearic Acid and other saturated fatty acids that have a higher carbon number.
If you want to experience first hand the difference between longevity and hardness, make a soap of pure coconut oil , and a soap of pure palm oil or if available palm stearin. you should notice after a decent curing time that both soaps are rock hard, but when used the coconut soap will wear faster while the palm soap will last at least twice as long. Of course other parameters will be different such as foam, harshness, cleansing. But you will get the general idea.

While most calculators are more or less the same when they calculate hardness and longevity. All of the calculators do not take into account the effect of the additives. So for more complex soaps you should rely on your experience in order to estimate those parameters.
 

TriniKellKells

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Jun 23, 2021
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Oh thanks for that clarification. I was just about to fiddle around with using Coconut Oil, Palm Oil, Olive Oil and Cocoa Butter in a small batch recipe for testing. Definitely going to write down your reply in my notes.
 
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