Definition of "mildness"?

[mzimm]

I'm not the most sensitive soap tester (I seem to love just about anything that lathers), so please see if you can give me a good description of what "mildness" means when talking about cured soap.
I understand the saponification that needs to take place during the initial cure time, and then the hardness factor that comes into play as water evaporates over the next few weeks.
But some of you have mentioned that longer cure times produce a "milder" bar, and that in many soaps the difference between 6 weeks and 8 or 10 is night and day because of this mildness. What do you mean? Is there more chemistry going on after "complete" saponification, and if so, what?

 

[dixiedragon]

Ask Deanna. She is the smart one. But yes. Stuff happens.

 

[DeeAnna]

To me, a mild soap is one that cleans my skin without making it feel dry or tight. The skin just feels nicely refreshed and clean. A younger soap, even with a recipe formulated for mildness, sometimes makes my skin feel a little bit dry or taut. I think a lot of this is because a young soap tends to be more water soluble. More soap on the skin => more cleansing. As the soap matures and the soap becomes less soluble in water, that feeling generally goes away.

ETA: Thanks, Dixie!

ETA2: Oh, and see this thread for more about what happens during cure: http://www.soapmakingforum.com/showthread.php?t=35831

 

[IrishLass]

For me, mildness is a very easy thing to judge. I just go by how my skin feels after using my soap.....

For example, assuming that the soap I'm using has been fully-cured, if my skin feels uncomfortably tight and dry right after I've washed/rinsed and patted dry, I consider that to be a harsh soap. But if my skin feels normal, i.e., no tightness, and I don't feel like I need to run for the lotion bottle post haste, I consider that to be a mild soap.

Is there more chemistry going on after "complete" saponification, and if so, what?

Yes, there is more going on behind the scenes after saponification. Many newcomers to the craft oftentimes confuse saponification with cure, but they are two completely different processes. Complete saponification is when the lye and oils have been chemically changed into soap, but like new fruit growing on a tree, it needs to ripen/mature on the inside before it's pleasant to use......what we call 'cure'.

Although we can't see it with the naked eye, during cure there are chemical changes that are still going on in the soap- changes such as decreased pH as it reacts with CO2 in the air, and also changes within the crystalline makeup of the soap itself that help it to lather better, become more mild, etc... Here's a snippet by our DeeAnna where she explains some of what is going on inside the soap after saponification is complete:

...Also, soap has a crystalline structure that gradually develops during cure. The crystal structure, being formed of soap molecules, is chemically neutral, but the spaces between the crystals are filled with a water-based liquid that is alkaline. Some of the alkalinity in this liquid is a natural consequence of soap being soap, and some could be excess alkalinity that will continue to react and neutralize during cure. The development of the crystalline structure, the entrapment of liquid within this structure, and ongoing but slow chemical reactions are also part of the increased mildness of soap during cure -- cure is not just about evaporating water.

Although we can't 'see' those kind of changes going on (at least not without a microscope or something), we can definitely feel their effects by using the soap at different intervals during cure and making sure to take down notes as you do so. Get a piece of paper or a notebook and outline sections on it for how your skin feels each time you use it (i.e., tight, dry or normal, etc...), and how it lathers (i.e., sparse, copious, more creamy, more bubbly, etc...) If you are like most of us, you'll be able to feel the soap gradually getting more and more mild and more and more bubbly as the days pass.

Edited to add: y'all were faster than me again! LOL


IrishLass

 

[DeeAnna]

It is because you are so much more eloquent and thorough!

 

[mzimm]

Thank you both for your insights. I am definitely going to add these notes to my recipe files.
Chuckling here bec I already don't need much excuse to visit my soaps at frequent intervals, and now I gotta bonafide scientific excuse to. :clap:

 

[Seawolfe]

If you want to try "soaps" that aren't mild, go wash your hands with laundry detergent or some dish soaps. uuuuugh

 

[TeresaT]

Ask Deanna. She is the smart one. But yes. Stuff happens.

First thing I thought was, "This sounds like a job for DeeAnna!"

 

[topofmurrayhill]

I'm not the most sensitive soap tester (I seem to love just about anything that lathers), so please see if you can give me a good description of what "mildness" means when talking about cured soap.
I understand the saponification that needs to take place during the initial cure time, and then the hardness factor that comes into play as water evaporates over the next few weeks.

But some of you have mentioned that longer cure times produce a "milder" bar, and that in many soaps the difference between 6 weeks and 8 or 10 is night and day because of this mildness. What do you mean? Is there more chemistry going on after "complete" saponification, and if so, what?

Not that any of the above is wrong, but one question is how to test it effectively. To do that, wash your hands and towel dry them. Wait 10 minutes and do it again. Do this three times and when you flex your hands any tightness you feel is the drying quality of the soap.

Ten years ago when I tried to use fractionated coconut oil in my soap, I only had to do this once to get a striking effect. But generally you have to do it multiple times to sort the wheat from the chaff. A good soap will not be particularly stripping through three cycles of this.

The chemistry that is going on after complete saponification of the soap, assuming it doesn't have excess alkali, is acidification. People say you can't lower the pH of your soap, but of course you can by acidifying it after it's made. This can only happen to a limited extent before the soap becomes less than soapy, but it does become gradually acidified by carbonic acid from CO2 dissolving in the residual moisture of the soap.

This additional mildness only comes from lower pH over time, but it might not compensate much for a poor initial soap formulation.

 

[Dahila]

When the soap does not cause my skin itchy, it is mild,

 

[mzimm]

Not that any of the above is wrong, but one question is how to test it effectively. To do that, wash your hands and towel dry them. Wait 10 minutes and do it again. Do this three times and when you flex your hands any tightness you feel is the drying quality of the soap.

OMG!!! I just did this exactly as you said with a bar of an "ugly" soap I did over 3 months ago. I'd put it away with others that I intend to grate up someday. After 30 minutes and 3 washings it's as though I just put lotion on, not washed my hands 3 times!

The light bulb is officially ON.

Note to self: No way is a soap ever leaving my curing rack and into someone's hands unless it feels like this.

Now ......I gotta dig up that "ugly soap" recipe. What was in it?.....