How to superfat an 8 lb batch

[judymoody]

Aye, the recipe will help, as I read it as being 32% CO (16 oz CO and 34 Oz OO and others = 50oz with 32% CO) so would really like to get clarification.

It's an 8 lb. batch with 16 oz. of CO, so 12.5% CO. Not enough to cause alarm, IMO.

 

[DottieF.]

I have a friend whose daughter is severely allergic to coconut oil. Soap made with it cause her skin to redden, get very itch and then peel.

 

[engblom]

I have been creating a table of the fatty acid makeup of common B&B oils, and I learned something interesting recently about the coconut and palm kernel oils. Some folks say CO is irritating to their skin, but PKO is not. I wondered why, since the fatty acid makeup as shown in Soapcalc et al. is fairly similar for the two oils.

Turns out it's the very short chain fatty acids not shown in Soapcalc that makes the difference. Here are the approximate percentages of capric, caprylic, lauric, and myristic acids in CO, PKO, and babassu, a fat that makes soap similar to CO or PKO soap:

Oil Capric Caprylic Lauric Myristic Total (C+C+L+M)
Babassu 4 7 50 20 = 81%
Coconut 8 8 46 19 = 81%
Palm kernel 4 4 48 16 =72%

Soap made from these four fatty acids is very water soluble, even in hard/salty/cold water. The net effect of this solubility means a soap made with CO, PKO, or babassu will be very good at dissolving fats. (Great for laundry, not so much for skin.) A soap with a high % of these fats needs a high superfat to reduce the amount of fat stripped from the skin. Essentially you're adding extra fat to the soap to protect the fats in/on your skin.

This tendency to be a harsh cleanser will be even stronger for soaps higher in capric and caprylic acids vs. soaps higher in the lauric and myristic acids. You can see that Capric+Caprylic = 11% for babassu, 16% for CO, and 8% for PKO. Guess which fat will make the milder soap of the three?

Not only is PKO lowest in the capric and caprylic acids, but it also has a lower total percentage (72%) of all of these four short-chain fatty acids. This may be at least part of the reason why some people perceive soap made with PKO to be milder than soap made with CO.

Keep in mind that my numbers are approximate, but they do tell an interesting story that might relate to the OP's troubles.

DeeAnna, this is again an excellent post! Do you have any book you get this kind of information from? I would want your source of information as you seem to have very much knowledge in less common topics.

I wonder if those shorter fatty acid chains is the answer to my enigma with a lot of lather from flax-seed oil. According to soapcalc.net it should not have any bubbles. By solving this problem I hope to be able to make a good shaving soap that would not be drying.

 

[dixiedragon]

By solving this problem I hope to be able to make a good shaving soap that would not be drying.

My sister was raving to me about how she's started to shave using conditioner, and that it works great, no razor rash, etc. So maybe you can make a non-soap product to shave with.

 

[DeeAnna]

"...Do you have any book you get this kind of information from?..."

Well, no, not exactly. I compile information from many sources, including old soap manufacturing books from the 1800s and early 1900s. These books are available for free from Project Gutenberg and Internet Archive, if you're interested.

But a lot of it comes from bits and pieces of information that I gather here and there and squirrel away in my head or on my computer. Most of the information comes from the research I do to answer questions that interest me -- often questions you all ask here at SMF. Sometimes I answer a question on SMF with the best information I have at the time, but I will often continue to research the topic for some time afterwards, so you'll see my answers evolve as I learn more and put small pieces of information together to create a better answer.

For example, one issue that comes up often at SMF is that coconut oil is more irritating to some people's skin than palm kernel oil. The Soapcalc fatty acid profiles are almost the same, so why is CO more drying or irritating than PKO? The short answer (I think) is that coconut oil has more capric and caprylic fatty acids than PKO. Why are those two fatty acids important to this issue? Soaps made from these short-chain fatty acids are going to be even more water soluble and even better at dissolving fats (aka drying out one's skin) than the myristic and lauric acids.

Digging out that answer has led me to wonder what other fatty acids might be overlooked by the soaping calculators, so I'm working, as I have the inclination, to create a table of the approximate composition of many common B&B fats. There is no one source for that data, so it takes some time, careful digging, and patient double checking. Soapcalc, for example, has a lot of oils in its database, but doesn't include fatty acids shorter than myristic or longer than linolenic. Working on stuff like that is helping me learn how the fatty acids contribute certain qualities to soap and that learning will lead me to .... who knows?

I love to teach, I'm a PhD engineer, and I'm definitely a geek. Does it show?

PS: Oh, and yes, I definitely also make soap.

 

[yadonm]

DeeAnna, we are so lucky you're here and so willing to share your knowledge with us. Thank you.