# The difference between CP and hot process soap



## naturalcare (Apr 18, 2013)

Dear friends,

I have read many articles about cold process and hot process soap making, and both of them has cure time lasts for weeks.

So can you please explain the difference between them to have better soap finally.

Thank you


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## BananaBee (Apr 18, 2013)

When you make a CP soap you work cold, that means 30-40°C. The saponication process needs much time at that temperature. So after some weeks to month the saponication is complete, it just needs some time to cure. A CP soap can be use after at least 1 month.

A HP soap is made at 60-80°C in a Crockpot or in a a pot in the stove. At that temperature the saponifation process is very fast (the higher the temperature, the higher the reaction speed). So all oil molecules get saponificated. When you make a CP, that needs more time.
A HP soap can be used immediately when its hard enough.

And a CP soap you can swirl like that, with a HP that is not possible.


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## DeeAnna (Apr 18, 2013)

"...So after some weeks to month the saponication is complete, it just needs some time to cure. ... A HP soap can be used immediately when its hard enough...."

Well, no, the saponification of a soap, whether CP or HP, is essentially complete when the soap temperature drops to normal room temperature and the pH drops to safe levels. That is usually only one to a few days for most CP soaps and right after cooking is complete for properly processed HP soaps. 

The CURE time is good for soaps made by both methods. This allows time to evaporate moisture from the bars and to complete the mysterious "mellowing" process that makes the soap milder and lather well.

HP: The soap is technically safe for use right after cooking, if done properly. The soap will often have a lower water content due to the cooking process. The appearance of the finished bars tends to be more rustic and textured. Fragrance and superfat oils can be added after cooking to precisely control the amounts of these ingredients in your finished product and to prevent the fragrance and oils from being changed or consumed by the lye.

CP: The soap requires more time to saponify. A wider variety of decorative coloring and texturing techniques are possible. The bars can vary from rustic to sophisticated looking. Fragrance may "morph" or even disappear by reacting with the lye. You cannot determine what oil is your "superfat" oil -- the lye consumes what it will, so it controls what oils remain as the superfat.

Common traits: Cure time is about the same for both to achieve a mild, "lather-some" bar. They are both lye-fat soaps.

Just my observations....


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## naturalcare (Apr 18, 2013)

thanks for your replies, and I want to ask if the process ( CP or HP ) used to make the soap effects on period of using ( the times we use the soap before we have to replace the soap bar ), as well as the smoothness of the soap bar.

Thank you


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## DeeAnna (Apr 18, 2013)

The thinking is that HP soap lasts a bit longer, all other factors being equal. That said, the choice of oils, water, and additives is probably as important as the process of making the soap, if not more so.

Smoothness? Meaning smooth texture, smooth appearance, or ??? I'd say CP soap probably looks smoother, all other things being equal. As far as how the bar feels in the hand -- the ingredients and how the soap is formed into bars adds so many variables, so it is hard to say if CP soap feels significantly different than HP soap.

HP is neither better nor worse than CP. Both methods make fine soap. You can pretty much use the same recipe with either method. So ... make your favorite soap recipe as CP and as HP and see what you think!


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## naturalcare (Apr 19, 2013)

Thanks DeeAnna for your reply, and in this case would it be safer to use HP than CP, I mean for the soap users or customers, also how can we be sure that the soap is safe for our skin and the lye used will not harm our skin during use it.

And is there simple tests using instruments to b sure that we have good quality soap that it will be really safe and also do its purpose to clean our hands.

thank you


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## DeeAnna (Apr 19, 2013)

"...would it be safer to use HP than CP..."

No. Correctly made, both are perfectly safe.

"...how can we be sure that the soap is safe for our skin  and the lye used will not harm our skin during use it...."

Design a safe recipe that will not be "lye heavy". If there is lye in the finished soap, you have done something really wrong. Test the pH after the soap is made to make sure it is in a safe range. Test the soap on your own skin as it cures for mildness. Give samples to friends and family and ask for their feedback.

"...And is there simple tests using instruments to b sure that we have good  quality soap that it will be really safe and also do its purpose to  clean our hands...."

Yes. Check pH with your tongue ("zap" test) or a pH meter or pH test strips. Use the soap on your hands and body during the cure time to test for effectiveness, lather, and mildness.


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## BananaBee (Apr 19, 2013)

DeeAnna said:


> Well, no, the saponification of a soap, whether CP or HP, is essentially complete when the soap temperature drops to normal room temperature



I think the saponification process is not done when the soap has room temp. The zap test shows, even after 1-2 days, that there is still free NaOH, that "brizzles". And after some weeks this brizzling is not more there, so THEN the saponification is done  .


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## naturalcare (Apr 20, 2013)

Regarding to the PH value, is it right that it should be around 10?

Thank you very much


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## VanessaP (Apr 20, 2013)

BananaBee said:


> I think the saponification process is not done when the soap has room temp. The zap test shows, even after 1-2 days, that there is still free NaOH, that "brizzles". And after some weeks this brizzling is not more there, so THEN the saponification is done  .



Virtually all correctly made CP soap is done saponifying within one week. If it zaps after a week, letting it sit any longer isn't really going to make the excess lye disappear and this soap should be rebatched.

Gelled soaps tend to be fully saponified within 24 hours. Ungelled, usually within 72 hours but it HAS been known to take nearly a week for it to stop zapping. Taking longer than that, and the soap is lye heavy and needs to be fixed.

HP shouldn't even be molded until it doesn't zap.


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## VanessaP (Apr 20, 2013)

naturalcare said:


> Regarding to the PH value, is it right that it should be around 10?
> 
> Thank you very much



Handmade soap pH varies, betwee 8.5 to 10.5. However, using standard pH test strips aren't very accurate. If you want to reliably check the pH of your soap, invest in a good pH meter and keep it calibrated. I personally do the tongue zap test. Why? Because my tongue is free and will always be able to catch the zap rather than rely on faulty batteries or low quality pH test strips.


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## BananaBee (Apr 22, 2013)

Yes Vanessa, of course you are right. I just wanted to mention, that the saponification is  not always done when reaching room temp.. Like you said, an ungelled soap needs more time  . And one should be awara of having an heavy NaOH soap :shifty:.

How do you measure the pH-Value of a soap? I read, you should make a solution with xx % and test this (with lacmus paper or pH-Meter). But some test their soaps directy on the soaps surface. 
I just always make the zapping test.


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## VanessaP (Apr 22, 2013)

BananaBee said:


> Yes Vanessa, of course you are right. I just wanted to mention, that the saponification is  not always done when reaching room temp.. Like you said, an ungelled soap needs more time  . And one should be awara of having an heavy NaOH soap :shifty:.
> 
> How do you measure the pH-Value of a soap? I read, you should make a solution with xx % and test this (with lacmus paper or pH-Meter). But some test their soaps directy on the soaps surface.
> I just always make the zapping test.



Hehehe I just do the tongue zap test


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