Cannot get soap to stop cracking, no matter what I do.

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Well-Known Member
Oct 21, 2018
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When I first started soaping I started with a basic recipe.

Olive Oil 44%
Palm Oil 32%
Coconut Oil 24%

I would always select the default for the water on the soap calculator (water = 38% of oil weight). I use wooden molds and I would cover them and insulate a lot. I usually soaped at around 120 degrees.
I made many batches with this recipe and NEVER had a batch crack.

As I got more experienced, I wanted to experiment with the recipe.
So I switched it up to this:
Coconut Oil
Olive Oil
Palm Oil
Shea Butter
Sweet Almond Oil
Castor Oil

Somehow (and I can't remember how) I evolved to the following:

Coconut Oil27.50%
Olive Oil32.50%
Palm Oil30.00%
Sweet Almond Oil5.00%
Castor Oil2.50%
Shea Butter2.50%

And I vary the water now depending upon what I am planning.

I typically use the default 38% oil to water on the soap calc alot.

But anyway, sometime around this time, every batch I make cracks. Every one!

So I stopped insulating.

Still cracked.

So I stopped covering

Still cracked.

So then I thought about reducing the coconut and the shea butter to this:
Coconut Oil21.50%
Olive Oil40.00%
Palm Oil30.00%
Sweet Almond Oil5.00%
Castor Oil2.50%
Shea Butter1.00%

I just made this one an hour ago. Soaped at 100 degrees. Left uncovered after pour with no insulation. 28% Lye Concentration.

And guess what, it cracked!

I tried this same recipe with a 33% lye concentration last night. It cracked.

Any ideas what to try next? Putting the soap in the fridge is not an option for me since I don't have one available for soaping purposes.

Thanks ahead of time!
It sounds like your soap is overheating. If you cannot refrigerate, try running a fan over the soap after pouring it in the mold. Do you have freezer space available? I put my milk soap in the freezer to prevent gelling. You don't have to have a designated refrigerator or freezer for soap. If you have room in the refrigerator or freezer you use, put the soap in there.
Have you tried to lowering the water to a 2:1 ratio with the lye, instead of basing it on oils?
I used 10% Shea butter and 5% Cocoa butter in my recipe, and I CPOP it, and it doesn't crack. Curiosity sake, is there a fragrance you're using? I know some of those can heat things up dramatically.
ETA: if you have an infrared thermometer, have you checked the outside temperature of the soap?
Also, if you're using a silicone mold, maybe use a bread pan to put the soap in an ice bath to cool it down? I've never tried it, but it's my best bad idea for cooling it down without freezer or fridge.
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I was also soaping in a 68°f environment. I soap with Aloe Vera Juice, and my lye/oils are generally combined around 120°f because I'm paranoid of false trace and my batter cools down as I work with it.
Also, what size batches are you making? Larger masses of soap have a harder time cooling off than smaller ones. As the soap's center gets further from the edge, it gets hotter as it is less influenced by the cooling effects of the air and instead subjected to the heat of the surrounding saponifying molecules.
The largest batch I'm doing is 2.5lbs, and for my purposes that is adequate. If I needed to go 5 lbs, I may be able to keep my batter as is. If I try to go full slab, I fully expect I'd need to tweak my recipe to remain workable for the pour time I want, and I'd also watch to see how much gelling it will do on its own before deciding how best to assist.
I would lower your lye concentration to 31-33%. Your CO is fairly high and using default water is probably causing the problem. I would just cover with the lid and watch it. I make milk soaps and 31%lye concentration and it never overheats. I use silicone lined wood molds with wood lids and lay a towel or two over the top.
Yes I tried both 28% and 33% lye concentrations.

Could it potentially be the weather? I wasn't having these issues in January with similar recipes. Although I am working in the AC, outside it is extremely hot and humid.

I soap in hot weather sometimes
100F for start ingredients is too hot for your conditions
you might do much better starting with near room temperature ingredients

some or all of these might help

heat and cool your hard fats in their own container
add the room temperature liquid oils to the fats then add the room temperature lye solution
stick blend briefly to emulsify

stir or use rest time to get the desired batter texture for pouring

running a fan over the molded soap can help
I agree with @marci .I would try starting closer to 80°F. I start at that temperature for all of my recipes and I don't have any problems with false trace or cracking.

I use heating pads like shunt2011 does to force gell and I don't have any problems.
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Just a few ideas: What type/size of mold are you using? You may need to soap with smaller amounts. I would start with less water. That should cool it quite a bit. If you are using a silicone mold, I would place it in the sink with some cool water just to the lip of the mold. If you see gel, add a few ice cubes to the water. If you are using a wooden mold, I would place on a cooling rack (like you use for cookies or bread), and run a fan over it.
Cracking is indicative of over overheating. Your formula(s) look fine to me, and reducing the water to a 33% lye concentration was a good step in the right direction (1 part lye to 2 parts water), as was soaping cooler and not insulating, so I'm left wondering what FO or other additives you might be using?

I ask because some FOs are notorious for causing overheating and soap to crack in spite of having done everything else right, and additives like honey can cause it, well as a whole lot of a certain oil: for example, my 100% coconut oil soap always overheats during gel and cracks on me. I learned a trick, though, to prevent it from cracking during gel ......I cover the top of the soap batter with bubble wrap (just press the bubbly part of the wrap down into the surface of the soap batter), and it helps to even things out so cracks don't form. Sure, I'm left with a honeycomb look on the tops of my soap, but it's better looking than a crack. :)

You can also fix a crack once it's already formed. The earlier you can catch it, the easier it is to fix, such as when in it's right in the act of cracking or as it's cooling down from the gel stage- spray the top of the soap with water or alcohol, place plastic wrap over it, then gently pat/rub over the cracked surface, smoothing it out/erasing the crack.

Another alternative to putting your freshly poured soap in the freezer or fridge, or blowing a fan on it is to place it in on ice in a cooler large enough to accommodate your mold, or even on ice in a large enough cardboard box will do just fine.

IrishLass :)
I agree with Shunt that it's probably your recipe and the lye concentration combined.
You are soaping in AC so outside temps won't effect you unless the AC goes off in the room while the soap is saponifying.
I soap at 110*F so 120*F is fine. If you drop that temp with palm and coconut you will get stearic spots. If you start putting it in and out of the refrigerator you will get partial get.

You've changed your recipe from the one that used to work for you by upping the CO and upping the butters. Both tend to make gel temps higher but coconut oil is the worst.
I'd drop the coconut oil to 10-15% max, don't use pomace for your OO, use 32% lye.
Maximum Castor oil 5%. Minimum of any other oil 10% as I can't detect any lower in soap (except for castor).
Don't add honey or an unknown FO (what FO are you using? name and company?). Don't use milk or sugar. Try a small batch to start.

Since you've had the problem you've stopped putting your soap in the mold and covering them. That is another difference.
I put my soap in a silicone lined wooden mold and cover with blankets summer and winter. I think it keeps the soap at a regular temp summer (and we get hot here) and winter.

Are you using room temp lye masterbatch and then mixing in the water (this will reheat the lye and may send it higher after you thought it had reached temp? Or are you mixing the lye and total water each time and waiting for it to come to temp.
Take really good notes. Don't lose hope, there is a solution.
You mentioned that you are using aloe juice. I would tend to lean toward the sugar in the aloe juice being the reason your soap is overheating. Are you using any other additives? There's lots of great ideas given to prevent cracking. If you don't want to gel then I'd pop your soap into the freezer. If you want to gel I'd cover the soap and keep checking it. As soon as you see the top start to bulge, uncover it and quickly cool it. Small cracks can usually be pushed back together right in the mold and some can even look pretty. :)
Try raising your mold so air can move under it, like a block under each corner.

If you are feeling frisky, put some bricks in the freezer overnight, and then rest the mold on top of the cold bricks.

You could also try making an icepack, and putting it in a cooler and putting the soap in the cooler.
When my soap cracks it is always due to the fragrance. Have you changed the amounts of fragrance you use compared to when you first started? Or changed the types of fragrances you buy or even brands? I usually can't predict which ones will overheat but I know that if a fragrance overheats and cracks on me one time it always do so unless I make changes.

Is your recipe size the same as it was when you first started? A smaller amount of soap will generate less heat than a larger amount. So going from a 1 pound to a 3 pound recipe size will affect how much heat the mold holds and how long it takes to cool down.

How bad are the cracks? 1 Inch down or 1/8 inch? Are they noticeable in the cut soap? If you are using the same fragrance and the same amount then these changes you are making should cause different temps in the mold. Is the crack better/worse on certain tries?

If it were me I would go back and make that first soap again with the same fragrance and same amount; trying to replicate everything you did and make notes; from where you sat the mold to how it was lined, to what you used to measure or weigh each ingredient and how you heated the oils. If you work on replicating that soap you may uncover some technique change you made that you think of as inconsequential but is causing your problems.
Wow, lots of responses since I last checked.

Just did 3 batches tonight. 1 Cracked, 2 did not. Only difference was the fragrance. Other than that, all batches were exactly the same.

I've actually figured out a way to repair the cracks. When I unmold it, I pick some pieces off the end of the loaf and use them to fill the cracks. Kind of like when you're caulking your bath tub or spackling drywall. Then I wet a paper towel with distilled H2O and rub it over the joint. This kinda helps smooth it out so you don't see it.