Longevity

kfrizzell

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Is "longevity" just be stability of the oils? So, for example, if I am using an oil that does not have a long shelf life, then Longevity will be below acceptable? Or is it linked to hardness and how long the soap will last?
 

Yooper

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“longevity” means how long it will last in the shower/use. Some soaps just melt faster than others. Usually a soap like 100% olive oil will get hard enough to pound nails, but still the longevity is low because of the way it reacts in water. You can always increase the longevity of all soaps by using a raised soap dish (so the soap doesn’t sit in a puddle of water and melt) but some soaps just disappear faster. That’s what longevity refers to in the calculator.
 

mobjack

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“longevity” means how long it will last in the shower/use. Some soaps just melt faster than others. Usually a soap like 100% olive oil will get hard enough to pound nails, but still the longevity is low because of the way it reacts in water. You can always increase the longevity of all soaps by using a raised soap dish (so the soap doesn’t sit in a puddle of water and melt) but some soaps just disappear faster. That’s what longevity refers to in the calculator.
Did the longevity calculation change? I'm troubleshooting a recipe for someone else. When I put the recipe in the calculator, the calculator returns 13 for palmitic fatty acid and 23 for stearic fatty acid in the fatty acid % section. Longevity = palmitic + stearic, which equals 36 if you add the palmitic & stearic together, but the calculator is giving 33 for longevity in the recipe property section.
 

Yooper

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Did the longevity calculation change? I'm troubleshooting a recipe for someone else. When I put the recipe in the calculator, the calculator returns 13 for palmitic fatty acid and 23 for stearic fatty acid in the fatty acid % section. Longevity = palmitic + stearic, which equals 36 if you add the palmitic & stearic together, but the calculator is giving 33 for longevity in the recipe property section.
No the calculation didn’t change. It’s still cleansing in the mix. Hardness is a part of it, but not only palmitic and stearic acids. Hardness- cleansing= longevity.
 

mobjack

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My reference is the Soapy Stuff website, here:

Soapcalc numbers | Soapy Stuff, which defines longevity as:

palmitic + stearic = longevity

while

hardness - cleansing is an estimate of longevity

I always assumed that the calculation being done by the SMF calculator made use of the actual fatty acid percentages to calculate longevity directly.
 
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