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Troubleshooting: Partial Gel in Cold Process Soap

In the Modern Soapmaking Troubleshooting Talk series, we explore various soap making problems and find out what went wrong plus share some tips and tricks to put the smack down on issues that pop up.

Today we’re talking about…

Partial Gel in Cold Process Soap

A 25 lb slab of soap with partial gel
A 25 lb slab of soap with partial gel

What is partial gel? The central area in the soap is darker and more translucent than the outer edges of the soap.

What causes partial gel? Saponification is an exothermic reaction, which means it releases heat. If there is enough heat during saponification, you’ll see a gel phase which is when the middle of the soap mass starts to look like translucent jelly.

I’ve temped a lot of soaps during gel and have seen temperatures up to 220° F. Wowsa!

Soap that has gelled tends to have a more translucent finish and a darker (and sometimes, more saturated) color. Ungelled soaps are more opaque and tend to have a duller final color.

If the soap cools off before the gel phase reaches the edges of the mold, the final soap will have a partial gel.

How do I prevent partial gel? A partial gel can be prevented by either forcing a full gel phase or by avoiding the gel phase altogether.

To force a full gel phase, try:

  • Soaping at 110° F to 140° F, depending on your formula and additives. (Be careful with additives that accelerate trace!)
  • Invert a cardboard box over the mold and wrap it with a fabric that insulates well, such as wool or felt.
  • Oven process the soap by placing it in an oven set to 170° F for about 15 minutes. Turn off the oven. Leave the soap in the oven until saponification is complete. (Don’t let heat escape the oven by opening the door to peek!)
  • Place the soap mold on a heating pad or a seedling heat mat during saponification.

To avoid a gel phase, try:

  • Soaping at room temperature, depending on your formula and additives. (Be careful with hard  oils or additives that have a low melting point, such as cocoa butter, shea butter, stearic acid or beeswax!)
  • Place the soap mold in an refrigerator or freezer, depending on the additives used. (A refrigerator is usually enough, except in the case of additives that heat up like honey or milks.)
Cut bars from a 2.5 lb loaf of soap with partial gel
Cut bars from a 2.5 lb loaf of soap with partial gel

Is the soap usable? Of course! A full gel phase is not required for saponification to complete. Heat is a catalyst of saponification, and will make the soap harder quicker.

A partial gel or ungelled soap may take longer to saponify, but as long as it’s formulated correctly, it poses absolutely no issues with usability.

Can soap with partial gel be fixed? If you notice a soap cooling off before a full gel phase, you can try one of the recommendations above to force gel phase.

You can also sometimes oven process a partial gelled soap (in the mold!) within 24 hours, if you discover it has a partial gel. This can take upwards of 30 to 45 minutes in the oven at 170° F.

Keep an eye on the soap so you don’t dry it out or overheat it. Watch for telltale signs of overheating like cracking on the top of the soap or any expansion of the soap in the mold.

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27 Responses

  1. Hi Kenna. Thanks for your great posts. I just had this partial gel in a batch of buttermilk soap. I used frozen buttermilk cubes and slowly added my lye until fully melted. All seemed ok – once in the mold, I did not cover for fear of over heating the buttermilk, but still got some darker translucent patches. Are you saying to freeze just the mold prior to filling with soap? Or are you suggesting putting the filled mold in the fridge/freezer to avoid the gel?

    1. For soaps with added milks or sugars, it can be beneficial to freeze the mold prior to pouring and putting the whole filled mold in the fridge or freezer to prevent gel. Or go for full gel by helping it along! I prefer all of my soaps to gel, so I keep an eye on soaps with milks or sugars, and help them gel if I need to. Hope that helps!

  2. Hi Kenna,
    you are the most spontaneous and ingenious soapmaker I have come across.

    I am a beginner, a month old.

    Just a ? Does the color, of a partial gelled soap even out at the end of curing? 4-6wks.

    If you ever get few secs, please check my blog and make a comment. I appreciate any input.

    Thank you so much

  3. am soap maker but i want to know more technique about modern soap, am glad to hear from you soon.
    yours Paul kapalata

    from Tanzania , EAST AFRICA

  4. Hi Kenna ,
    I’m fairly new at soap making , and loving every minute of it . This weekend I made a batch of pinetar soap . I have made this before and loved it. This time I try to experience with adding soybean oil and used a calculator to adjust the lye and water content . After 48 hours it has a consistency of Tofu . I combined at around 100* and used cardboard and towels to cover . Any suggestions would be helpful .

    Thanks so much

  5. Hi Kenna! Thanks for the post! Your soap is beautiful!! Are the spots on the blue soap stearic acid spots from palm oil? I have two batches of soap with spots exactly like that. They PH test at 9.5 & 10 so I don’t think it is lye. The spots are hard and waxy.

  6. I don’t have an account. I also have a problem with all my soaps going through partial gel. Please help me! I work with a five pound mold that won’t fit in the freezer.

  7. Hi Kenna!
    I make soap cupcakes since 2 years. But sometimes, (a lot of times actually) the frosting lifts/comes off the bottom. But not always! Sometimes…and i don’t know why!! Sometimes all frostings on the same batch, sometimes a few frostings on the same batch! When i have this troubleshoot, i see my soap are crumbly on the top (but just on edges)
    Can you tell me why i had a crumbly and soft soap on edges (the middle is hard/normaly)?
    Do you think it is because the phase gel is partial?
    i couldn’t insulate silicone molds. (it’s difficult to insulate a lot of little molds for muffins!)
    The temp of the room is not hot…maybe 64°F or 66°F. And i don’t work in hot temp with oils and lye.

    excuse me for my bad english, i am not english! 😉

    and a lot of thanks for your answer!!!


  8. Hi Kenna, thanks for this articles, I allways get a lot of information from you, my question is: what additives could make trouble in gelling? I do have problems especially with those that have oatmeal and spices, they come out with a white circle in the center, when I use them they are ok but not estetically, I’d like to know what I’m doing wrong, thanks

  9. I have never had much trouble with partial gel using my wooden mold lined with freezer paper. However, i recently bought some small 2-lb wooden molds with silicone liners. I have had a lot of problems with partial gel. Even when i put them in the freezer, they still partial gel. I started using the cpop and that was working great but the other day i made my coconut milk shampoo bars, and cpop and they still partial gelled. Was this caused by the milk? I realize the silicone liner is causing the problem. Any advice? Thanks

  10. Hello Kenna I was thinking about another way to avoid partial gel in a soap. I haven’t tried it as I always CPOP my soap to ensure full gel, but my readings recommends to discount water in order to prevent partial and gel in general as low water recipe needs higher temperature in order to reach gel.

    What do you think about it? Have you tried it?


  11. Can a coconut milk soap that was in the freezer, and still partially gelled be sold to public? Or should it be? Can it be rebatched? So frustrating when it looked so milky white n upon cutting I saw the partial gelled center!

  12. I have been making soap about a year. Recently I was asked about oxygen soap. Do you know anything about this? I would like to try it but am unable to find a recipe. Thank you.

  13. Hello! Thank you for this very helpful post. I’m a relatively new soap maker and for my fourth batch, I decided to try my own recipe after using a lye calculator and deciding to use a water discount – I set to making the soap. I used aloe vera juice instead of water and added a couple table spoons of pureed pumpkin to the batter when it reached trace. Knowing the extra sugar could cause issues, I put the batter in the freezer for the first 24 hours and then moved it to the fridge for the next 24 and pulled it out and let it sit for an additional 24 at room temperature (since it was still a bit goopy). I finally cut it this morning and it had the partial gel circle in the middle! The only think I can think of is that maybe I added the lye mixture to the oils when it was still too hot (it was about 130 F). Any advice for next time?

    1. Hey, Tara,
      Since a lot of the factors that control trace also control gel, I suggest you read this article: Controlling Trace.

      I think you are on the right track to lower your oil temp. We like around 110 degree F for most recipes. The article I just mentioned also touches on how your amount of liquid influences gel, so you might need to tweak that too.

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