Lots and lots of clay

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Feb 1, 2023
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Hey all!
Inspired by this recipe Lots & Lots of Clay Soap - Humblebee & Me I wanted to see how different amounts of kaolin clay changed soap.
Originally, I was trying to see how much it took to make soap noticeably whiter. I failed to take water absorption into account, and got some interesting results.

I used this recipe How to Make Gentle Hemp and Shea Soap - Humblebee & Me because it was high in hemp oil which was supposed to make the soap a little darker than normal, making it good for testing whitening.

I split the batter into 4:
- 0 clay
- 2 tbsp per pound of oils
- 4 tbsp per pound of oils
- 8 tbsp per pound of oils

Unfortunately, my SB was broken, so it was hand mixed, and not very well. On top of that, I did not know that you’re supposed to mix the clay with water before you add it.

This is what I got:

The layers are in order, such that the top had the most clay and the bottom had none. Completely backwards to my expectation of whitening. And even more than lightening, the clay increased the green hue of the oil.

I had two hypotheses as to what could have caused this: 1) the clay somehow increased gel 2) the clay was absorbing the water, creating the same effect as “ghost swirls”.

I tested again adding 2 tbsp of kaolin clay per pound, this time in 100% CO soap with colored additives, and forced the gel phase in the oven, and left some soaps outside in the cold:


The top row is soap without clay in the oven; the middle soap is with clay in the oven, and the bottom row is soap with clay out in the cold. This time, I mixed the clay with some water first.

Clearly, the clay actually did lighten the soaps a bit, even in the oven, which means that it wasn’t the gel, it was the water (I think).

Then after two months I did a literal blindfolded test of the soap with different clay amounts:

(as you can see, the soap with no clay at the bottom developed more soda ash, supporting the idea that the soap with a lot of clay had less water available)

Maybe my hands are completely insensitive, but I was not able to pick up a noticeable difference between the soaps except a slight change in texture.

We recently got through our first soap with all the layers, and there was again no noticeable difference, like either the top or bottom dissolving more quickly.

When I followed the original Lots and Lots of clay recipe with French Green Clay, which uses about 10 tbsp per pound of oil, I actually got a substantially rougher texture, which I quite liked, as well as a bar that hardened really quickly, so already a month after curing it was ready to use, and had a nice creamy lather, dark green color, and strong scent.

So in conclusion, you can add a LOT of kaolin clay, it just may not actually change much. I had more of an effect with green clay.
Addendum: turns out the high-clay soap is a little more brittle than than no-clay soap, so when it was in its final stage as a little stub, a corner of the top high-clay part broke off, then the no-clay part easily bent in half without breaking.
I don’t know if anyone designs soap with this last stage in mind, but there you have it.
I don’t know if anyone designs soap with this last stage in mind, but there you have it.
I guess the next question is, based on your experiemnt, "What is the optimum amount of clay to add to the batch without fear of the soap becoming brittle?"
What recipe did you use? I had a water:lye ratio of 1.9:1, but I didn’t add extra water with the clay.
not sure the ratio but it was probably about 2-1, no extra water though. the more research I do since then, because now I'm hearing you should only use 1 teaspoon per pound instead of 2 tablespoons--also forgot I experimented with coconut milk replacing water and it was pretty thick. I am still experimenting. Now trying to figure out what to do with all these hunks of dry clay soap ;)
I'm refreshing this thread because I was also confused by Humblebee and me's lot's and lot's of clay and all the information I've looked at saying .5-1 teas per pound. I just made a loaf with Kaolin and French Pink clay with 2:1 water:lye ratio. No extra water but I mixed the clays with fragrance and a little of the liquid oils.
Others say one tablespoon per pound of oil. Is it one or the other or somewhere in between?
I would say it depends on the recipe.

The Humble Bee and Me recipe:
Per 500g (1.1lbs) oils: 10 tbsp white kaolin clay

I know from experience that my recipe that I regularly add clay to would not perform well with that much clay. I use 3 TBSP for 1000g oils.
I have only used tsp measurements when using clay for color.

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