Soap cracking after cutting

[szaza]

I recently made some soaps that started to crack after they had been cut. I already have a likely suspect, but I wanted to run it by you guys to see what you think.

Recently I ran out of isopropanol and because I didn't gel my soaps and I didn't want a thick coat of ash I decided to spritz with ethanol instead. It's only the latest soaps that were spritzed with ethanol that cracked. The cracks look kind of similar to the way high butter soaps look when they've been in use for a while. My guess is that since ethanol doesn't evaporate as quickly as isopropanol, the soaps got too wet, dried again, got too wet again and they ended up cracking because of this cycle, but that's really just a theory.

There's one batch that was only spritzed with ethanol and got severe cracking, while the other batch still had isopropanol the first day and a few days of ethanol after that (if I get ash, it often seems to come at day 3 for some reason). I think both soaps got the same amount of ethanol spritzed on them and mainly the age at which I started with ethanol differs (by one day, I made the soaps one day apart) The older soaps that were still spritzed with isopropanol are generally fine with just a few cracks here and there, while the latest soaps are full of cracks.

Recipe in case it matters: 20% coconut, 30% cocoa butter, 50% HO sunflower, the older soap had 30% lye conc. the one I made a day later had 33% lye concentration. Just before those soaps I made a few batches with a lot more cocoa and/or shea butter that didn't crack, so I'm sure it's not caused by the cocoa butter.

 

[penelopejane]

I don' think the IPA or ethanol would cause cracking. I think it may be the temperature you soaped at?

 

[szaza]

Hmm.. I soaped at the exact same temp as all the other soaps I made that week that didn't crack (oils and lye between 35-40°C, starting temp after mixing +-37°C), so that seems unlikely to me.. I've never had problems with IPA, only ethanol is suspect in this.

 

[penelopejane]

No other additives at all?

 

[szaza]

Citric acid at 2%.. that's what I always use. Though I did just buy a new bag from a different brand

I cut bars from a new batch yesterday and decided today to sacrifice one bar and spritz it with ethanol to see what happens. The recipe was similar but not the same (replaced 30% of the sunflower oil with RBO). I might have started a bit too late as they'd been cut for 24hrs before I started spritzing, but I'm curious if any cracking shows up.

I used the same CA again, so if all of them crack it could be the citric acid

(Sorry for the multiple posts I'm thinking as I write)

 

[penelopejane]

I use CA at 1%. Di you have a photo of the cracking?

 

[szaza]

My phone camera is pretty bad and doesn't focus well on closeby items, so I hope you can see it properly

 

[szaza]

Ugh.. that soap was so pretty after unmolding and look at it now!

 

[dibbles]

I'm so sorry that happened. All that work and such a pretty soap, and then to have it crack like that is so sad. I hope you figure it out.

 

[Jersey Girl]

View attachment 45531

My phone camera is pretty bad and doesn't focus well on closeby items, so I hope you can see it properly

oh man.. that’s such a pretty shimmy pour! This technique was on my list to try next. I hope you find out the cause of the cracking. I would venture to say it could be the ethanol if that’s the only thing you did differently.

 

[szaza]

Fortunately I made a similar batch before that that shows significantly less cracking and doesn't contain as much curcuma (which went from really bright orange to almost white within a week). I've had curcuma fade on me before, but never to this extend. I'm glad it at least smells good (*knocks on wood)

 

[szaza]

Hmm all the new soaps - also the ones that weren't sprayed with ethanol started to develop cracks. The soap stayed soft a lot longer than the 2 other batches even though it traced a lot quicker and got a bunch of ash. I tried to plane and bevel today, but some of it just crumbled apart. (The other 2 batches of cracked soap were already cleaned up before cracks appeared). Since they stayed soft for so long and weren't spritzed with alcohol the soaps are quite ashy. I'll try to steam off the ash and see if more cracks appear (sometimes ash can also cause cracking in my experience.)
I'll try to make soaps with and without the new citric acid this week or next week, though my boyfriend suggested maybe the air in my curing space is just too dry (it's been very dry here for several weeks and our skins are also drying out like crazy). It just started raining, so if a lack of humidity is the problem none of the next soaps I make shouldn't be getting cracks.
Another theory could be my lye. I used the last bit of masterbatch from a combo of old and new lye. I have a feeling the last bit of masterbatch is often giving me a hard time, though this masterbatch was only 2 weeks old (one week when making the shimmy soap) and the last 3 batches giving me trouble seems unlikely. Also, the 'old' lye was opened in February and stored in a dry bucket system, so not that old, the new lye was a newly opened bucket of lye. I cleaned out my masterbatch container with distilled water before making the new masterbatch.
These are the cracked soaps after cleanup, but before ash removal
And after steaming:


(Edited to add a picture)

 

[Jersey Girl]

Maybe try making a batch with a fresh batch of lye (not masterbatched). Could the lye have gotten too concentrated towards the bottom Of the container?

 

[Mobjack Bay]

oh no... your shimmy is so pretty and poured so well. If I was just looking at the soap without any explanation, I would think it was dry and brittle. It will be interesting to see how the rainy day soaps turn out in comparison.

I had some weird results with CA at 2%, as texture issues, possibly brittleness, and also crystallization on top. Based on PJ using 1% with good results, I dropped back to 1% and everything has been fine since then.

 

[szaza]

Weird thing is, I've been using CA at 2% for a long time and never had problems. Also, I went back to my notes and the batch that was made one day before the one I showed above (the shimmy) and only got a few cracks, but not as many, was made with a bit over 1% CA from the old bag that I'd been using for months without problems (I ran out and just recalculated my lye because it was evening and the stores were closed)

(This is the piece that shows the most cracking)

Eta: the cracks in the shimmy soaps look different than the semi circle soaps.. the cracks in the shimmy soaps are sort of sticking out, the edge of the crack is being pushed out, while the semicircles have cracks that go inside the soap, without the edges being pushed out (for now) if that makes sense... I'm curious whether that'll change!

 

[Mobjack Bay]

The cracks in the semi circle soaps look like the kind of cracks you could make in a block of something softer and bit deformable, like young cheddar cheese, while the cracks in the shimmy soap look more like cracks in mortar, mud, pottery clay or even wood that dried. I can't imagine the problem being due to the CA, but I just thought I should mention it.

 

[penelopejane]

Have you been adding extra lye for the CA?
I don’t know what the problem is. The soap in post 7 looks like the soap is drying out at different rates and it had too much water to start that doesn’t make sense if you had a lye concentration of 33%. Might have dries extremely quickly on one side?
Did you add extra water with your colours? Did you do your masterbatch calculations right? Did you do your extra lye for CA right?

 

[szaza]

I used soapmakingfriend to calculate CA, water and masterbatch. I've been using that calculator since the beginning of the year and haven't had any trouble with it yet.
No extra water in the colorants (all mixed in oil or oil infusions). I'm a bit lost at the moment to be honest.. I'll continue spraying some of the new soap with ethanol and leave some alone.
@Mobjack Bay thanks for confirming the cracks look different to you too. The semi circles were softer when they started cracking than the shimmy soaps. Let's see how the cracks behave when the soap hardens out more!

 

[cmzaha]

Have you actually tried making some without the cocoa butter or taking it down to 10% and adding in Shea at the higher percentage? Maybe try splitting your HO Sunflower with OO, if it is accessible at a decent price. Even I not a huge lover of OO it is lower in palmitic than RBO, or use your RBO again as the split. It may still be your cocoa butter although I know you mentioned you used a higher percentage without a problem. You have to start somewhere. Was it the same batch of Cocoa butter?

Maybe try each of your oils as a tiny 8 oz batch and see if you can narrow down leaving. Dissolve your citric acid measure out your 2% for 4 oz split the batch at emulsion and stir in the citric in half the 8 oz batch. This will tell you if it is citric acid causing the problem or something else. It will be work but may be well worth the effort. Force these to gel in the oven or on a heating pad. I would keep the lye concentration at 31% if lowering the cocoa butter.

 

[szaza]

Thanks for your input @cmzaha I'm planning out a whole series of experiments to find the culprit before attempting another 'pretty' batch I really don't want to have this happen again..
I'll probably start with the exact same recipe as the shimmy soap and spritz a few bars with ethanol, a few with isopropanol and leave a few unspritzed to see if there's a difference and if I can replicate the cracks. After that I'll assess what test to do next, lowering the cocoa butter and/or changing the amount of citric acid. Maybe I should also assess gel vs no gel, since I didn't gel the cracked soaps..

Today I saw one crack that looked more like the shimmy cracks in one of the soaps that were spritzed with ethanol the past few days.
I also realized I never spritzed the end cuts of the shimmies with ethanol and they don't have those distinct cracks either. They do have a whole lot of ash that in some places has a crackling look, but I've seen that before with ashy soap and I think it looks different than the cracks on the shimmies. I'll try to take some pictures tomorrow.

I've started to doubt about the cocoa butter. The batch I was convinced I did with 40% cocoa was with 40% shea woops! That means the highest I've gone before these last (cracking) batches is 25% cocoa. There were no cracks in those soaps, but it was a different bag of cocoa butter. With the current bag I've only gone up to 20% cocoa with 30% shea and 20% coconut - also without cracking.

Olive oil is easy to source here and I often use it as a split. I'm still playing around with recipes to see what I like and it was purely a coincidence there wasn't any olive oil in the last few batches