# What does longevity mean?



## Izzye (Mar 12, 2017)

I made a batch earlier using soapee's recipe maker and I noticed it has a little box of soap stats, one of which was longevity. Is this in relation to the amount of time the soap will last unused before it starts to lose its properties? Or is it the amount of time the soap will last when being used? 

I presume the stability is how well it will retain a shape? Or should I be looking out for volcanoes as I only got 15% on that one?


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## cmzaha (Mar 12, 2017)

It is a guideline for how long you soap will last. Higher the number the longer lasting the soap. The number comes from Subtracting the Cleansing value from the Hardness Value. It is based on the solubility of the soap. A 100% CO soap is very hard (79) with a cleansing value of 67 in soap calc. 79-67=12  which is a very soluble soap that will not last long. This also is why 100% CO soap will lather in salt water. I am sure DeeAnna will pass by and give a better explaination. She is whom explained it to us in the forum to begin with. I like my number to be no less than 27 after subtracting the Hardness and Cleansing number. 100% Palm Oil would give you a number of  49 for longevity, which in my opinion would be a lousy soap, although it would last forever but not much for bubbles.


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## lsg (Mar 12, 2017)

From what I have read longevity is how long the bar lasts.  Keeping a bar of soap in a container or dish that allows air flow around the soap lets it dry after each use.  I assume that stability is referring to lather.  I use SoapCalc and SoapMaker 3.


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## TheDragonGirl (Mar 12, 2017)

The amount of time it will last being used!


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## Nao (Mar 12, 2017)

To my understanding longevity is how long the bar will last when used. Stability is for how long the lather will stay fluffy with big bubbles. 

   Vulcanos is usually caused by overheating from to much sugars or fragrance oils that just doesn't work very well in soap. 

   Also next to the "recipe properties "-square on soapee is the "fatty acids %"-square with is very good to keep an eye on too to get a better understanding of which oils to use for which properties in your soap.  All oils is made up of different proportions of fatty acids and all fatty acids contributes to different properties in the oils, and therefore the properties in the soap.  

   Lauric and myristic  fatty acids are very water soluble and makes for a very lathering, cleaning and not so long lasting bar. They also makes the bars hard, but hardness doesn't necessarily makes a long lasting bar. There is a lot of lauric acid in coconut oil, that is why soaps high in coconut oil is hard, bubbly, cleansing but not long lasting. 

   On the other hand stearic acid is not so water soluble so that makes for a longer lasting bar.


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## DeeAnna (Mar 12, 2017)

I came up with the idea, as far as I'm aware (please let me know if I'm in error!) I think the Soapee guy took the idea from our discussions here on SMF and ran with it. It's not on any other soap recipe calc that I'm aware of. 

The number is the sum of the % stearic acid and % palmitic acid in the recipe. You can calculate it as Carolyn explained or you can look at the fatty acid profile of your recipe and add stearic and palmitic acids. Either way works. I have about the same expectations as Carolyn -- I'm looking for 25-30% for the combined palmitic and stearic when roughing out a typical bath soap recipe. Too low and the soap doesn't last sufficiently long in the shower. Too high and the soap doesn't lather as well as I'd like.

Stearic soap and palmitic soap are not very soluble in water, and these soaps are also add physical hardness (as in hard like a rock). These two properties contribute to the longevity of the soap, meaning how long the bar will last in the shower. It has nothing to do with volcanoes or overall shelf life or anything like that. 

Other ingredients in the recipe can affect the longevity of the soap, so I use this number (and the other numbers for cleansing, bubbly, etc.) as a guideline only. Many beginning soapers obsess over formulating the perfect soap recipe and want to know what "numbers" they should should shoot for to create that Holy Grail recipe. There is no such thing. There are recipes that work well for most people most of the time, but no one recipe will ever be perfect.


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## cmzaha (Mar 13, 2017)

Yep I just knew DeeAnna would show up!  I also figured the Soapee guy came up with it from DeeAnnas idea. He used to visit the forum.


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## ngian (Mar 15, 2017)

Well yes, mcnazar (the developer of Soapee) was asking this forum for some feedback to his soap calculator project, and he did try to incorporate most of our guidelines / remarks. So this calculator is somehow a creation of a team work here.

It has been almost two years since then... time really flies! 

http://www.soapmakingforum.com/showthread.php?t=55570


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## Cassandra Jackson (Feb 15, 2019)

What other oil will help the Coconut Oil Soap last longer? for the longevity stats...please help


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## Dawni (Feb 15, 2019)

Cassandra Jackson said:


> What other oil will help the Coconut Oil Soap last longer? for the longevity stats...please help


The hard butters (cocoa, shea and mango are the most common) contribute and lard and tallow as well. Not sure if the waxes, too?


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