What is the hardest soap you have ever made?

[Happysoap]

What is the hardest and long lasting soap you have ever made?

This is just a “what-does-this-button-do” type of a question. I thinking to make a small batch of the hardest soap I possibly can just to see how it behaves in comparison to what SoapCalc gives me. Any tips/ideas?

 

[ResolvableOwl]

Technically, my hardest “soap” was when I dissolved finely grated stearin candle wax (FFA-type palm stearin) into excess lye (for titration = SAP determination). Essentially pure palmitic/stearic acid. It's not a saponification (ester cleavage) reaction, but neutralisation, so it would react within seconds.

The lye was boiling, still I didn't get more than a few % of the stearin dissolved before the solution turned into a gooey mess. I diluted with (cold) water, just to watch how the gel would solidify, and it nearly burned upon reheating. In the end I managed to salvage something that I could barely scoop into a mould.

After cooling, it was literally rock hard, no exaggeration. It felt like a piece of plaster and shattered into pieces when I hit it with a hammer. While technically soap, it was extremely lye-heavy (on purpose) and still had an absurdly high water content. I let it carefully dry – it shrank by an unbelievable amount (to about half its original size, while retaining its shape), and became even harder, like pumice or heavy-duty styrofoam. I filed off the amount I needed for the titration – which was no less of a pain, since this stuff is soap, yes, still incredibly badly soluble in cold water, so I had to heat it up to near boiling, and keep it hot for the whole titration, otherwise it would gel.

I was so glad when this project was over (and doubly so that it was worth the hassle – I got a reasonable SAP of 0.158, close to the value of pure palmitic acid). The freshly identified sodium palmitate, after neutralisation of excess lye with more candle filings, proved as a valuable ingredient to harden up M&P soap.


For such a soap made from 100% palmitic acid, soap calculators spit out a soap that is maxing out the “hardness”/“longevity” scales, which can't be more true. The “creamy [lather]” number is high as well, yet I didn't manage to get this soap lather at all (it was just too insoluble), so I had no chance at all to judge the qualities of lather.


I don't know if this is valuable for you in the sense of your original question. If you want to make a maximally hard-by-the-numbers soap that is still usable as soap, better go the 100% coconut oil way. It comes out hard and scratchy too, but at least it dissolves reasonably and gives of lather happily. Offset the irritiating properties of high-CO soap with as high as 20% lye discount, and/or make a bar with hardly any superfat to compare it with.

 

[Ford]

Probably my mechanic bar. 70% coconut oil. Used a round mold. It's like a hockey puck.

 

[The Efficacious Gentleman]

Hardest is a 100% co low SF stain bar, but it wouldn't be long lasting if you used it for bathing (but you wouldn't want to!)

I find my salt bars tend to last a good while though, even with a high co amount

 

[KiwiMoose]

Mine was (is) a bar of Zany's No-Slime Castile (85% OO, 10% CO, 5% castor) made with real sea water for the lye solution. It was made in January 2020 and my sister is still rocking a bar in her bathroom, which seems to live forever. I first gave it to her last year in about July - and it was already hard then, now it's a year later and it's still there! It's the guest bathroom - used for hand washing only.

 

[Obsidian]

Mine is 80% lard, 20% coconut with a 5% SF and a chelator of some kind.

It was so long lasting, I got tired of looking at it in the shower lol. Its also a very nice mild soap

 

[maryloucb]

100% bear fat soap.

 

[DeeAnna]

Long lasting isn't necessarily the same as a physically hard-like-a-rock. A person shouldn't assume they're the same.

I have olive oil soap that's surprisingly hard, but it's short lived in the bath. I have made mostly coconut oil that is likewise. I've made soap with high % of palm or tallow and they are both hard and long lasting. I've made mostly lard soap that is not as hard, but is also long lasting.

 

[cerelife]

For hardness + longevity, it would be 5 year old Castile soap for me!
Back in the summer of 2016 I got on a Castile kick and made several batches. They most likely aren't true Castile soap because I added Sodium Lactate and silk to my lye water along with sea salt. I let them cure for a year and they were lovely, but not good sellers for me so I pulled them for personal use. And then of course I forgot about them because I'm always excited to use whatever new soap I've made.I stumbled across them this past Christmas and I've been using the same bar twice a day as facial soap since then and it's maybe half the original size so I estimate it's going to last for approximately 12 months. Granted it would NOT last that long in the shower, but it's amazing for facial soap! These 5 year old bars are hard as a rock, but very weigh very little - and they have the coolest velvety feel to them.
This probably isn't very helpful since most people aren't going to want to make a soap that takes years to cure, but they are honestly worth the wait!

 

[GoodLuckFishing]

Sea salt soap

 

[GemstonePony]

78% mango butter, 15% coconut oil, 7% castor is one of my favorites. The 78 % mango butter, 22% coconut oil variation might feel even harder, but I haven't made it to check. Either way, it'll trace in a hurry.

 

[Peachy Clean Soap]

i'd halfto to say my salt bar seems very hard' its still curung August is the six month mark I can use it.

 

[JuliaNegusuk]

100% coconut 20% superfat soap, hard as a rock, unmoulds in a few hours but doesn' t last, boohoo, its my favourite soap. Seasalt soap is hard and I think, longer lasting.

The ultimate I have come across is a 22% laurel oil/78% olive oil Aleppo soap I have just been using prompted by a recent post. I have had it for several years, it was past its use by date when I began using it, and I only used half the bar and it's still going strong after several weeks regular daily use. When I bought it I it comes in a thick, almost cube shape, so I cut it in half with a hacksaw in my wood vice, it was that hard. Its so long lasting I am actually getting bored with it! I think it us the longest lasting soap I have had for ages, but I haven' t used commercial soap for a very long time.

 

[JuliaNegusuk]

Sorry, I didn' t make it! Didn't read your question properly.

 

[Tara_H]

I kind of have to ask, how are you all measuring how hard your bars are? I mean, once it's hard enough that it doesn't deform with normal handling, I'm not sure what more I should be expecting from a bar of soap?

 

[Zany_in_CO]

It was made in January 2020 and my sister is still rocking a bar in her bathroom, which seems to live forever. I first gave it to her last year in about July - and it was already hard then, now it's a year later and it's still there!

I'm glad you mentioned that. I thought it might be just me, but I'm impressed by how long lasting ZNSC is. I use it AM & PM to wash my face daily. Not only does it last, but it keeps it shape and doesn't get mushy or soft near the end like my other soaps do.

That being said, for your purposes @Happysoap, I'd recommend messing around with a basic formula, changing one thing at a time for comparison:

BASIC TRINITY OF OILS

 

[Ugeauxgirl]

I made a soap with 85% tallow, 10% coconut oil and 5% castor. Hard as a brick

 

[amd]

Zany's no slime castile. I've tried it twice and within hours it's too hard to cut even by hand. I gave up.

 

[Zany_in_CO]

Zany's no slime castile. I've tried it twice and within hours it's too hard to cut even by hand. I gave up.

Hmmm. That's weird. It shouldn't be that hard. I wonder what's causing it???
PM me before you make it next time and we can review your method.

 

[KiwiMoose]

Zany's no slime castile. I've tried it twice and within hours it's too hard to cut even by hand. I gave up.

I always make it in cavity moulds