Longevity Query

[AndyRoo]

Hello all,

Please can I ask how much faith you all put into the 'longevity' rating in soap calculators?

Obviously I know that CP soaps don't last as long as the store bought ones, and how long they last is influenced by how they're stored / how often someone uses them / how long they get used for etc., but I find it really difficult to make a soap that meets the all of the target ratings!

The calculator I use recommends a longevity score of at least 25, whereas my batter has a score of 18. And while I don't want to make a soap that only lasts a week, I also struggle to increase the amount of butters in it without making the batter impossible to work with.

I don't use palm oil, and I am vegetarian, so I refuse to use lard or tallow etc.

So my question is: how much attention do you all pay to the longevity rating when using calculators?

Cheers,
Andy

 

[Misschief]

Obviously I know that CP soaps don't last as long as the store bought ones

I dunno. How long do you want your soap to last? I have a dear friend who used to make soap; earlier this year, her mother gave her a couple of bars of soap that she'd given to her mother.... about 20 years ago. She said she'd give me one and that it still smells (she only used essential oils) and that there was no DOS.

 

[DeeAnna]

I don't agonize over a percent or three, but I do want the palmitic and stearic acid content (the longevity number) to be somewhere around 30%, maybe a little higher. Some want this percentage to be in the mid 30s.

Palmitic and stearic acids make soap that is (a) relatively firm and (b) relatively insoluble in water. Both of these qualities make for a longer lived soap as well as contribute to the overall mildness of the soap on the skin.

The shorter-chain fatty acids (lauric and myristic), the unsaturated fatty acids (oleic, linoleic, etc.), and ricinoleic acid make soap that is more soluble in water, so the soap doesn't last as long.

The rage of late is to add salts (table salt, sodium lactate, etc.) to soap to make the soap physically harder, but I'm not sure people understand a harder soap doesn't necessarily last longer. Compare a crystal of quartz to a crystal of salt. Both are quite hard, but salt dissolves easily in water; quartz doesn't.

I don't know of any additive that makes the soap less soluble in water. AFAIK, only stearic and palmitic acids (of the fatty acids commonly found in soap) can do that trick.

 

[cmzaha]

I will tell you my soaps last as long if not longer than store-bought soaps, but I do use Palm in my vegan soaps and tallow/lard in my non-vegan soap. You can also use soy wax to up the longevity in soap. It all depends on the solubility of your soap an example being a high CO soap is highly soluble because of its high myristic and lauric acids. A 100% long-aged OO soap will last a very long time although not a soap I like because of its fatty acid profile. DeeAnna just explained better than I.

 

[DeeAnna]

Yeah, good point about aging/curing the soap, Carolyn. A soap that's well cured (months to years) will last longer compared with the same soap that's fairly young (weeks to a few months). That means to some extent a generous cure time will add some longevity as well. Commercial soap makers can use milling* to add longevity as well, but most handcrafted soap makers don't have access to milling machinery.

* Some people use milling to mean rebatching, which is a process of melting soap. I'm not talking about rebatching -- I mean real milling where dry soap is squished between chilled granite or metal rollers to make it hard and dense.

 

[GemstonePony]

Also a vegetarian soaper here- all praise to the whisk! Seriously, my stick-blender is on stand-by in case of ricing, otherwise emulsion/trace is achieved by whisk and spatula for most of my recipes. Longevity is very important to my testers, and I gravitate towards accelerating fragrances. Depending on my additives, I may SB my lye solution or my oils, but it's rare for me to SB the actual batter unless it's a single-color soap.

 

[KiwiMoose]

What's your typical recipe @AndyRoo?
As DeeAnna states - you need to keep your palmitic and stearic up for more longevity. I achieve this by using 20% soy wax in mine, along with 10% Shea, 20% OO and 20% RBO.
You could also have a go at Zany's No-Slime castile - my sister has a bar of that in her bathroom that i made in January this year and that stuff is HARD. She has had it in the bathroom for hand washing since August and it's barely gotten any smaller.
ETA I made the 10%CO and 5% castor version of Zany's NSC.

 

[AndyRoo]

I use:

40% Olive Oil
30% Coconut Oil
15% Shea Butter
10% Sweet Almond Oil
5% Castor Oil

I thought about lowering the CO 5% and increasing the Shea by the same amount, but then I lose the bubbly goodness which my friends/family tell me they like!

 

[AliOop]

@AndyRoo you might considering taking 10% off the CO, and adding 10% cocoa butter. Or taking 5% off the CO, and using 10% each of shea and cocoa butter.

Then you can re-boost the bubbles another way, such as using aloe vera juice instead of water, or adding sugar or sorbitol to your water before adding the lye.

 

[AndyRoo]

@AndyRoo you might considering taking 10% off the CO, and adding 10% cocoa butter. Or taking 5% off the CO, and using 10% each of shea and cocoa butter.

Then you can re-boost the bubbles another way, such as using aloe vera juice instead of water, or adding sugar or sorbitol to your water before adding the lye.

I try to keep my recipe as simple as possible and without too many ingredients, otherwise they get costly!

 

[AliOop]

I hear ya! There is that fine balance between making soap the way we really want it, and not breaking the budget. But even if you don't add the cocoa butter, adding sugar is a pretty cheap way to boost bubbles after reducing the CO.

 

[KiwiMoose]

Unfortunately - you can't really have both - lots of bubbles AND longevity. One counteracts the other. So as long as you are using 30% CO, your soap will be fairly soluble. How about reducing your CO by 5% and adding it to something else with high stearic or palmitic fatty acids? Maybe reduce your superfat to only 3 or 4%? Higher superfat can inhibit bubbles. Definitely use some sugar in the water coz that's cheap, and I grow my own aloe so it costs nothing. It grows like a weed here, but maybe not so much in the UK.
Have a look into either RBO and/or Soy Wax - both are super cheap here, but again, not sure about the UK. RBO is my cheapest oil and works out to about 2.65GBP per litre.
ETA - I see Waitrose sell it for about 2GPB per 500ml, so it is dearer over there, but still relatively cheap?

 

[Zing]

My recipe is all vegetarian too and unfortunately, @KiwiMoose is right about the bubbles versus longevity. My hard to soft oil ratio is typically 60:40. I used to use up to 30% coconut (I don't find it drying as others do) too but have been adjusting my recipe for a harder bar. I'm not home right now but will try to remember to share a recent recipe. I used way more butter than normal (which usually reduces lather) but upped my coconut and I have been pleasantly surprised at the bubbliness. Good luck to you,

 

[earlene]

You can add sugar, honey, or another additive that contains sugar to boost the bubbles. Also eggs in soap tends to create a more bubbly soap, in my experience. There are several threads here that address the use of bubble boosting additives and some that specifically address the use of eggs in soap.

 

[Zany_in_CO]

So my question is: how much attention do you all pay to the longevity rating when using calculators?

I don't pay attention to it at all. I will say, IME (in my experience), the longer the cure, the longer the soap lasts.