Hot process - additives before cook or after?


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May 3, 2019
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United States
I would like to try doing a HP batch next but I am used to CP. I always see that people advise adding extras after cooking it. Is there any problem with adding extras before cooking it? For instance I like to add kaolin clay and I find that it is so much easier to disperse with a stick blender in the oils. If I don't do that I always end up with tiny little specks of clay, even if I mix it to a paste in a tiny bit of oil first. It's going to be impossible to do this after it has cooked and it's all thick.

I would also like to try adding oatmeal to this HP soap. Can I do that before too?

I mean, it doesn't seem like this would cause any problems? After all I see people adding sodium lactate to the lye water for HP soap. But I thought I'd ask here first just to be sure! Thank you!


Well-Known Member
Sep 15, 2018
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Personally I think it depends on what additive and what it's gonna do for the soap.

Clays, for sure you can add whenever you feel like. I've actually noticed that unless they've been thoroughly hydrated though, clays added after the cook makes lumpy batter that's difficult to design with. It's a risk I sometimes take coz I use them as colorants. If you don't use enough water (I use anywhere between 2.7:1-3:1 depending on recipe and design plans) to begin with even adding it up front can make lumpy batter which is ok if you're aiming for plain soap.

I've added charcoal after the cook - makes uneven grey, speckled stone looking soap. Adding the same amount with the oils made a more consistent colored soap, but still grey, just darker lol

In my case for example, I also add my coconut milk powder and rice powder to my oils, sometimes at trace when I forget lol

Sugar water, sodium lactate or yogurt are used for fluidity, sometimes together, so obviously these are added after the cook. I've never noticed a difference in sodium lactate added to lye water, to oils, or after but I've stopped using it.

Anything oil based can be added after the cook as well. I add my superfat separately, just in case some of the good stuff is retained since saponification is mostly done at this point. My infused colorants obviously get added after as well.

I wouldn't add chunks of foodstuff after the cook.. Might spoil or get moldy. They'd have to be fully incorporated into the batter and saponified with the rest to decrease those chances.


Well-Known Member
Aug 8, 2018
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I completely agree with Dawni;)
For some things it might have an advantage to add before or after cook, but the things you mention are absolutely fine to go through the cook stage.
I also second the warning about clay making lumpy batter (and brittle soap!) if not hydrated enough when added to HP. It also seems to mix better with water than with oil. How about making a slurry with distilled water and adding it to your lye water? Haven't done this before myself but read about people doing this to intensify the color of the clay.. (the clay won't mix with the oils when you make a slurry with water)


Supporting Member
Sep 29, 2015
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What the two above said. That said, it's better to hydrate the clay in a little extra water outside what is needed for your soap, if you use clay. That way you can let the clay sit and watch how much water is being absorbed by it. I am tempted to get another small slow cooker to make some HP but I need space to put it.