Does Hot process soap has advantage over cold process?

Hi everyone.
I have a question about the advantage of Hp vs Cp soaping.
I am almost familiar with the difference between HP and CP but I Would like to know does HP soaping has a big bold advantage over CP? like adding superfat after cook, essential oils or other botanical additives so the benefit of them can be preserved from harsh pH. (is that really true? can we add for example botanical extract after cooking soap and it saves its benefist for skin in high temperature and pH lets say around 9.7?)
I would appreciate if someone could clarify it for me.

Being able to add things in after the cook is the big advantage, yes! It keeps the lye from destroying things, it also makes it so that you can use less fragrance oil for the same amount of scent, or use a misbehaving fragrance oil safely. It also does allow you to choose which fat the soap is superfatted with instead of it being whatever the lye didnt grab.

Ely said:

Hi everyone.
I have a question about the advantage of Hp vs Cp soaping.
I am almost familiar with the difference between HP and CP but I Would like to know does HP soaping has a big bold advantage over CP? like adding superfat after cook, essential oils or other botanical additives so the benefit of them can be preserved from harsh pH. (is that really true? can we add for example botanical extract after cooking soap and it saves its benefist for skin in high temperature and pH lets say around 9.7?)
I would appreciate if someone could clarify it for me.

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Remember that soap is a wash-off product. You don't leave it on your skin to soak up the essential oil or botanical benefits. You wash, then you rinse. So how effective are the additives going to be with a quick once-over, or if the user is doing a 20-second wash, 20-second exposure?

Yes, you don't run the risk of certain additives accelerating trace when you add them after the cook. But it's not that easy to add them after the cook to a less fluid batter, so you either add more fluid to help with that, or you work really really hard to mix hot thick soap with your new ingredients. Not impossible, but hard on the hands, elbows and so forth.

I don't know how you are going to get such an accurate pH reading unless you plan on investing in rather expensive equipment. Strips are known to be rather a rough guide rather than an accurate measurement of pH.

As far as a 'bold advantage' over CP, I don't really think so. Not in my opinion. They take just as long, if not longer, to cure. It makes the house too hot in the summer (but it warms up the house in the winter.) It takes just as long to make the actual soap, sometimes longer, as making CP soap. One drawback that I see is that fine, intricate swirls are more difficult, and in some designs, not at all possible with HP over CP.

If saving money for fragrance is a goal, perhaps it is an advantage, but I haven't really seen any reports or studies that show the actual cost effectiveness to prove the point. Such a study would have to take into account the cost of power used to heat the HP soap as an off-set to the cost of FO savings over making CP soap using the same formula. It may save some money, but how much, I have no real clue.

Ditto what Earlene said^^^.

I, too, personally see absolutely no bold advantage of HP over CP, unless I'm working with a naughty FO that doesn't take kindly to being CP'd, or when using a lot of stearic acid, such as I do with my shave soap formula, that is. Those are the only times I do HP.

To me, the oft-touted reason most do HP (selective superfatting) has not been proven to my satisfaction. Although it seems logical that the fat you add after saponification will remain untouched, it may get some interference from the subsequent process of 'dynamic equilibrium', whereby in order for the soap to maintain its solid crystalline nature, the molecules are constantly changing partners by hooking up or unhooking up with each other. It's hard for me to explain this ongoing dance that takes place at the molecular level, so I'll let DeeAnna explain it. Here is a excerpt from one of her posts which can be found here:
http://www.soapmakingforum.com/showpost.php?p=394531&postcount=5

DeeAnna said:

When we make soap, we're combining a weak acid with a strong base just as I've described. The resulting bar of soap is not a boringly static, unchanging block of stuff. Soap is a "colloid", meaning it's a complex structure of solid soap molecules surrounding droplets of water-based liquid. The chemistry going on in this colloid is constantly changing -- it's like a huge party where all kinds of microscopically tiny people are circulating around. Some people "hook up" with each other and some just cruise. Some may hook up, but later unhook, cruise for awhile, and hook up with someone different.
In chemistry terms, all this partying and circulating is called a "dynamic equilibrium". Obviously, many soap particles are created when the fatty acids and the sodium ions "hook up" more or less permanently to form the chemically neutral molecules we call soap. But there are also the chemical loners who circulate in the watery liquid inside the soap structure -- these include some sodium ions (Na+), some fatty acid ions (Ste- and others), and the H+ and OH- ions released by the lye and the fatty acids.
In soap, the pH of this dynamic equilibrium is naturally alkaline, meaning there are more OH- ions from the lye wandering around than there are H+ ions liberated from the fatty acids. This will be true EVEN IF there are exactly as many fatty acid ions in the soap as there are molecules of lye -- or even if there are more fatty acids and fats than lye molecules. It's just the nature of the beast when you're dealing with the dynamic equilibrium between a strong base and a weak acid.

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It would be cool if someone could do actual tests to prove that such-and-such a fat added after the cook remains totally untouched, but in light of the above^^^, until that happens, you'll have to color me skeptical about it.


IrishLass

Dear IrishLass thanks a lot for your comprehensive answer and the link.

Dear earlene thanks for your comment. I use pH meter to check the pH but you are right it was better to tell the pH is between 9 -10.

Even a ph meter isn't accurate unless you are testing it at the proper dilution rate. Zap test is about all you need to make sure there is no active lye