Strange hole in the center of my CP soap

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May 3, 2020
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I’m pretty new to soap making (I have 4 successful cold process batches and 2 hot process batches under my belt). I am also totally new to this forum, and would love some help identifying what I did wrong. I have made this general soap recipe several times with no problem. I got a little over confident I guess and decided to try making a test batch of a matcha and mint version with goat milk. The basic recipe (without goat milk) is made with olive oil, coconut oil, sweet almond oil, cocoa butter, and castor oil, with 10% super fat (I like a really moisturizing soap). I used the normal amount of water, and added the amount of powdered goat milk that would correspond to that volume of water after combining the oil and lye water (not quite at trace). I added the usual amount of fragrance (mint, lemon, and lime essential oils), plus matcha powder. I made a 2lb batch, combined ingredients at 110F (my usual temperature to a bit low), and put it in a silicone and wood log mold. I unmolded and sliced it today (4 days after making it) and the center looks strange. The top looked totally normal, not cracked, no alien brain. Through the whole loaf, something oily seems to be leaking out of the center, and the very middle has this odd, stringy section. What is this, and what caused it? I can think of a number of things I probably did wrong in my whimsical attempt to try something new when my old recipe was working so beautifully:
- didn’t re calculate superfat content and adjust lye to account for fat in goat milk, which may have led to higher superfat than intended
- used normal amount of water plus goat milk powder, rather than decreasing water volume to account for volume of goat milk powder
- used two new to me ingredients at once (matcha and goat milk)
Any insights would be much appreciated! I haven’t found pictures of anything like this. Thank you!


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This is from overheating. The stringy bits could be lye crystals, are the hard?
This soap needs to rebatched or thrown out. If those are lye crystals, its unsafe to use.

Make sure you add all the oil that leaked out if you rebatch.
I agree this looks like overheating. From your receipe, the most likely culprit is the sugar in the goat milk. This kind of thing can happen with goat milk soaps or soaps with honey, fruit purees, sugar, etc. Here are some examples from the web:
For any soaps I make with sugar, honey, or milk, I usually mix around 96-100F and then it spends at least one hour in the fridge. Additionally, you can play with decreasing the water:lye ratio as increased water can also promote overheating. The larger the mold, the harder time you will have keeping heat under control as heat has a harder time escaping from the center. Also, Silicone can trap heat and you can consider trying a wax paper liner in a wood mold for recipes at risk of overheating

Question, is the leaking fluid caustic? If there is any risk that your lye and oils were not mixed properly, then I would throw out the batch. However, I feel like I see those stalagtite formations in overheated soaps with sugar and I wonder if that is the sugar not the lye. Hopefully someone else can comment on that.

On your list of concerns:
- didn’t re calculate superfat content and adjust lye to account for fat in goat milk, which may have led to higher superfat than intended; I don't recalculate for goat milk powder; your superfat will be slightly higher. You can consider recalculating if you use a large amount of heavy cream to a recipe
- used normal amount of water plus goat milk powder, rather than decreasing water volume to account for volume of goat milk powder: That should not be an issue since you added solid powder, not additional goat milk liquid. However, higher water:lye ratios can increase risk of overheating.
- used two new to me ingredients at once (matcha and goat milk): sounds like a lovely combo :); it is easier to figure out the issue if you do one new ingredient at a time, but I think you have a clear culprit here.

Thank you for the help! Yes, it looks like those pictures!! The stalactites that I see look like spun sugar from baking - crystal clear and shiny. The fluid that is leaking is definitely oil, and isn't caustic. Everything was mixed well: I mixed with my stick blender for quite a while, then added the matcha and goat milk powder, mixed some more, then added the essential oils and mixed more. I did pour at a fairly light trace because I've had a tendency to over-blend to medium trace or more, and then have trouble getting the soap into the mold. Does this mean the soap is usable after all?

I made another batch at the same time, with the same base recipe but with brewed coffee as the liquid, the same amount of powdered goat milk, coffee oil for fragrance, and added coffee grounds. That one went into poly tubing suspended inside a PVC pipe and it looks perfect - it went through gel phase and is an even color and consistency (though also a little greasy on the outside). No split at all in that one. I guess the silicone + wood was just too much.

Is it possible to allow goat milk soap to go through gel phase without risking overheating? Or should I try to avoid gel?

Thank you!!


If I do rebatch it, unfortunately I did slice up the entire loaf, which means a lot of oil leaked out onto the cardboard that I placed the slices on. How do I figure out how much oil to add back?


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