Dealing with soap that seizes

A student of mine recently contacted me for some advice about one of the most common soapmaking mishaps when using the cold process method: soap seizure. No, the soap doesn’t go into convulsions (although it’s been known to make some soapmakers have fits!). As a soap batch is being mixed, it’s usually the consistency of cake batter. Sometimes rather thick cake batter, but smooth and pourable nonetheless. When a soap seizes, it thickens unexpectedly and suddenly, sometimes ending up as thick and curdled as applesauce. The worst is when it becomes so hard, so fast that no amount of stirring or blending with a stick blender will fix it. You end up with a hard mass of soap in the pot right in the middle of mixing; what soapmakers call “soap on a stick”. *shudder*

The usual culprit in this sorry business is the scent: either natural essential oils or (much more frequently) synthetically manufactured fragrance oils. In general, anything that smells spicy (cinnamon, clove, ginger…) or very floral (jasmine, lilac, gardenia…) tends to speed up the chemical process that turns the soap batter into soap bars. When it speeds the process so much, you don’t even have time to finish blending in the scent and BOOM!: seized soap.

It’s no shame when it happens. But there are ways to avoid (or at least manage) a soap seizing.

Research your fragrance
Chances are that someone else has already made soap with whichever fragrance or essential oil you want to use. Forewarned is forearmed! First, check with the supplier of the fragrance oil. The best ones have soap information right on their website listing any issues like discoloration or acceleration (soapmaker code for “watch out with this one!”) If the info is not on the website, get in touch and ask. If they don’t know, it may not be worth risking it.



Also check The Soap Scent Review Board, an online community of soapmakers that shares their experiences with hundreds of fragrance oils and essential oils from dozens of suppliers. See if anyone else has used your fragrance oil of interest and what the experience was like. And remember to add to the community by adding your own soapmaking experiences, good or bad.

Doing research may save you a lot of aggravation, but remember: different soap recipes may react differently to the same fragrance.  Someone else’s experience may not be exactly yours. Testing a new scent is always a bit of a risk.

Dilute the scent
If you have a fragrance or essential oil that you really want to use but you know (or suspect) that it will be problematic, you can try to dilute the oil, and hopefully minimize the acceleration. Instead of adding the scent after the base oils and lye are mixed (as most folks do), add the fragrance oil to the base oils before adding the lye solution. This way the scent is blended throughout the oils and may react better in the presence of the lye.

Cool it down
Soapmaking is chemistry, and the warmer the chemical reaction the faster it will head to completion. To slow down the reaction and keep your soap batter smooth longer, try cooling your base oils and lye solution before mixing them together. As long as the oils are still liquid and flowing, having everything even as cool as 70ºF will still result in great soap. And it may give you enough time to get your soap blended and into its mold before it hardens up.

Even after taking all the precautions, no one can guarantee that they will never experience a soap batch seizing (soapmaking is an adventure!). But I hope that these tips may help you get the smooth, great-smelling soap that you’re looking for!

What was your worst soap seizure? Do you have any other tips that might help? Leave a comment and let’s learn from each other!


25 thoughts on “Dealing with soap that seizes

  1. These are all great tips! One other thing you can do is put the pot on the stove and started cooking it. It will be hot processed soap instead of cold process, but it will also make the soap workable.

  2. my seizure had nothing to do with ‘accelerating’ fragrance or essential oils: mine, after research, was related to ‘castor’ oil, and, too high temperatures: it took me by surprise, since i had never experienced this; apparently, when using certain base oils, like castor, which i was using for ‘shampoo’ bars, my temperatures for the oils and lye mixture were too high (about 110 F) ; i didnt even have time to add fragrance……………i suffered miserable as i was forced for about a month to use ‘bought’ shampoos, after having been spoilt with my shampoo bars for over 1 1/2 years; my hair started to dry out instantly, and my scalp started to itch;;;;; i love homemade all natural soap and shampoo?

    • THANK YOU SO MUCH! I’ve been trying to solve the seizure mystery… trying cooler, no spicy or floral fragrances, etc etc ETC and it never occurred to me that it might be the castor.
      You have saved us many tears. I wish I had thought to research it before my last batch, but whatever! I’m happy to know now!

  3. Pingback: Concentration? Percentage? How do I figure the water amount for my lye solution? « The Sirona Springs Blog

  4. I have heard that using full water helps lessen the effects of an accelerating fragrance. Will I have not tested this I thought perhaps one of you might have.

    When I know a fragrance will accelerate or seize I do a hot process soap in the oven. Once it has gelled, I add my additives and let it cool below the FP of the fragrance then include it. This system does work well, however the soap texture is more of an organic type!

  5. Hello, I am a new soap maker and I use the hot process. the last few batches I have made has not cooked the same as the others have. They do not rise up the sides and flip over as the others had, they just sit there and thicken. I think I have saved them by adding a few tablespoons of water and let it cook. I end up with the waxy mashed potato concoction after cooking it for 20 to 30 minute. My question is what am I doing wrong?

    • Diane, you may not be doing anything wrong. Were these last batches different recipes? Sometimes different oils will act differently in the crockpot and not rise up on the sides and fold over. They will still turn out fine. Just test for complete saponification (by the tongue test or with phenolphthalein) just like with the other batches. As long as the reaction is all done and there is no more active NaOH, you’re good to go!

    • Susan, it depends a lot on how well you were able to get it blended before getting it in the mold. Take a look at it once it firms up: is there any liquid oozing from it? That suggests that the mixture wasn’t able to stay emulsified and may have separated at least in part. But if it is not oozing (maybe just a bit rough or “rustic-looking”) then it will be fine to use.

  6. I made soap CPOP, got to trace separated the batch in 2 mix my colors and fragrance then my creations started seizing, as a new experience to me naturally I panic, I went to research what to do in the soap forum, but when I got back (15 min later), my better half had put it into molds and put it in the oven LIKE nothing was different with the batch….I decided to finish the soap like usual, we cut the soap today… it looks great a little rustic but It turn out beautifully.

  7. I just made a batch of soap using olive oil, coconut oil, and soybean oil. NO fragrance oils. everything was going fine, it started to trace, it looked good, like vanilla pudding. then when I started to pour it in the molds it started frothing up and overflowing the molds, volcano style. I’ve been making soap for 10 years and have never had this happen before. anyone have any ideas on what might have occurred?

    • It sounds like your soap batter may have been too hot, Dominique. That’s what usually causes soap volcanoes. Either the oils and/or the lye solution was too hot when you blended them. Or maybe some other ingredient caused overheating. You mention there was no fragrance oil. How about essential oils? Some, like cinnamon and clove, can cause overheating, too. Or did you add any honey, or other sweet ingredient? That can also cause overheating. Hope that helps you figure it out.

  8. Hey everybody! I wanted to register to a The Soap Scent Review Board, but i don’t get what kind of email should i use?do i have to buy an account or is there some other way?

  9. last holiday season I made orange cinnamon soap. It seized up terribly but I was able to get it into the mold. Everyone seemed to like it but it wasn’t too pretty. I just tried to make this soap again as I had requests for it. Same thing! Seized up.The madder root I used for color (red) turned bright purple but again I was able to get it into the mold. When I went to unmold it, I was surprised to see that the purple color had turned a very pretty red. As I cut the soap into bars I was amazed at how well it turned out. Is there any way to avoid seizing when using the cinnamon and orange essential oils? This soap is a pain to deal with. I wanted to do a swirl with the color but due to the seizing I was lucky just to get it into the mold.

    • Mary, it’s the cinnamon. All the spice essential oils (cinnamon, clove, etc.) tend to do that. I can only suggest lowering the amount of cinnamon if you can, and mixing the oils and lye at a lower temp. Cinnamon is such a lovely scent; too bad it can be hard to work with!

  10. Hello, I am a new soapmaker, I want to start making soap for sale. My fear is using the lye. Am not good with chemicals and I am afraid I might use a little more and this might cause problems to my customers. How can I measure the ingredients with surety that it won’t cause problems. am also not good in using grams and all that. please help! 😞

    • Hi Adam, I recommend that you learn how to make handmade soap either from someone you know who is knowledgeable, or an online source that is reputable. (I have a suggestion: 😉 There’s no need to be afraid of lye; only careful.
      Then, practice, practice, practice. I believe that you need to make cold or hot process soap for at least a year before starting to sell it. You’ll need to develop one or maybe a few good recipes. You’ll want to be sure that you can make successful batches over and over again. And you’ll want to be sure that your soap is still good 3 or 6 or 9 months after being made (and sitting on a shelf waiting to be sold). But it’s definitely possible. Many professional soapmakers started out like you! Give it a try and see how it goes.

  11. Hello I was hoping someone could help me. I have been working on a batch of liquid castille soap and sadly even though using HP my whole batch just curddled just as I had reached trace. I am not sure but it may have been the high temperature but it is the second time I have this happen and I am just getting frustrated. I would appreciate any help you could give me.

  12. I wonder if it would work to pour the essential oil / fragrance oil into the mold first, then pour the unscented cold processed soap on top? Then maybe swirl around the EO / FO a bit to mix it in? I have an EO I love but it causes my soap to seize every time. I may have to try it.

  13. I had problems with my soap recipe seizing until I started adding liquid lecithin, making sure the temperatures of lye and oils were 70’s, using higher water concentration and using a whisk instead of the stick blender. Now I am able to do zebra swirls.

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