Help with castile soap, please

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Jan 18, 2020
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Hi, dear forum,

So I just successfully did my first (and second) batch of castile soap (or bastile soap) according to
I mainly did it because I moved from the US to Europe and I can't get hold of dr bronners at a decent price where I am, and I also like the idea of doing my own soaps from a sustainability point of view

It is fine but I have a couple of questions on how to make it better

1. Scent. It has a distinct soap smell about it so I tried adding essential oils I did a 3% concentration (mix of cedarwood Eo and fig FO) and a 10% (cedarwood EO) but it doesn't seem to hide the soap smell. any suggestions on what I am doing wrong?

2. The soap is very runny. Is there any way I could make it thicker without using glycerine, and keep with simple over the counter natural additives. I read something about salt? if so how much?

3. Should I dilute it more? I am using it as hand/body soap and it dries out my skin quite a lot. PH strips say the PH is between 9 and 10. Any suggestions?

All answers would be appreciated!!
I’m not the best with liquid soap yet and I think some of your questions are beyond my skill but I’ll answer the best I can

1) by 3% concentration do you mean you added 3% EO by weight or a mixture that was 3% EO + 97% carrier? That part could just be forum expected language vs how you’re used to talking about EO’s.

When adding scent to liquid soap you first need to figure out safe usage rates then you need to pick an emulsifier. 3% does sound like a safe usage rate but you’ll have to double check with a supplier or a source like the Tisserand institute to make sure you’re not going to hurt anyone (seems like dumb advice to give sometimes but sometimes people don’t know where to check).

Most of your liquid soap is water. Since oil floats on water.... you’ll need to pick an emulsifier to keep the mix from separating. Most suggest polysorbate 80 or similar. There may be more natural products if that’s more your taste, it I’m not familiar enough to recommend any.

To sum up - you’ve got a few options to make a scent stick: correct usage rates and emulsifiers. Again, not the most familiar with liquid soap making but I’m running on the assumption you either didn’t use enough or the mix is separating and if you’re using a pump the scent is floating above the straw opening.

2) I have not experimented with thickening soaps. From what I’ve read you can use salt in high oleic soaps (usually means a lot of olive oil) as a thickener but they do hit a saturation point where they will stop working. You have to use trial and error to figure it out. Everyone’s so is a bit different and your climate may affect things.

I’m not sure about other natural thickeners but I’m not there yet in my own experiments.

3) in terms of science: soap has a pH of 9-11. That is part of the definition of soap, if you change it too much then you no longer have soap (usually by people wanting a “mild” product). Most on this site will also discourage you from even testing pH. At home kits are always slightly off, salt content (soap is also scientifically categorized as a salt) affects accuracy, and test strips cannot tell you if the is excess lye in your end product. Technically you’ve only proved that you have soap, your numbers are in a proper range.

Don’t dilute your soap any more. All dilution does is add water which counteracts your questions in #2.

If you want suggestions about a less harsh soap we need to know exactly what YOU did. I read through your link and I like that she stresses soapcalc for changing the recipe. I did not like that she just gave you a recipe. You should ALWAYS run what you’re doing through soapcalc (or a different calculator if you find a favorite). My usual method is to measure my oils and input exactly what my scale says into soapcalc. This slows me down, gives me a second check, and allows me to account for any assumptions I’ve made (like where did I put that bottle of olive oil I know I had on my shopping list but forgot I added it after I last went shopping).

A quick test for human error/newbie mistakes: put a drop of the diluted soap on your tongue. If you just taste soap you did everything correctly, if you feel like you licked a 9 volt battery you’re soap is lye heavy (this is known as a zap test). If you feel the zap let us know along with your exact process/measurements and we can walk you through fixing it. If your soap doesn’t zap then it may be a recipe issue.

I didn’t run the given recipe through soapcalc but I did notice it was very high in coconut oil. Coconut oil is nice in lotions but harsh in soaps. Many people use coconut oil at 20% or less to counteract the harshness unless they’re using a high super fat (super fat is excess oils that you add to soaps to help balance out harsher ingredients). Liquid soaps tend to use 3% or less in SF. To contrast, a bar of soap usually has a 5%SF but specialty soaps can have up to 25%. I feel like the harshness you’re feeling is probably the high coconut oil. One way to counteract that is to use an emulsifier to add extra oil to your soap. Another way to counteract it is to make a soap without the coconut oil and then mix the two to end up with a lower % of coconut.
I was having trouble with your expression of did you tried a batch of 3% FO and a batch of 10% EO and neither worked, or it's one batch of 3% FO+10%EO blend? Color me confused.
Also, it could be just me but from my own experience, there will always be a bit of a soapy smell underneath all those fancy EOs and FOs. I used to sniff every bar of soap I can find in the supermarket and those artisan/farmer markets and my conclusion still stands: I can smell the soapiness no matter how strong the eo/fo is. It's soap, after all.

How to thicken a solution easy, cheap, and safe: xanthan gum, guar gum, or if you want to make it real fancy, hydrocellulose.

I also agree with BattleGnome that the CO in original recipe is too high. I have quite oily skin and I only use 30% CO in my soap recipes, in winter I will reduce it to 20-25%, liquid soap should be even lower than that as there is no SF. 40% CO is definitely too high. I'd say maybe try 15% CO or lower next time and see if you like it? That's ratio I use for my facial bars.
Liquid soaps are little more limited with the superfat. Unless you use PS80, you may have some oil on the top of your soap if it is over 3%. Also, liquid soaps tend to call for more coconut oil in the recipe. Recipes with 20% CO might be fine for bars but in a liquid soap, you will likely get less bubbles.

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