Why do you need to neutralize the NaOH and KOH?

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marykj

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i made liquid soap paste. Turned out the ph (using the ph paper) is 9. So need to reduce the ph to about 8 or less. Thus I have been reading/ searchinh on when is the best time to put citric acid to do it, ie when it is in the paste form or the already diluted to liquid soap.

but i have found alot about putting in citric acid 2-5% before even making the paste.

so my question why do we need to neutralize the NaOH or the KOH even before the saponification process happen? and also if can answer my first question on when to put the citric acid should also help..

think this is a silly question do tell me why?

TIA

MaryK
 

DeeAnna

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First thing is pH cannot tell you whether you need to neutralize or not. And you'll never have a lye-based soap with a true pH of less than 9. The normal pH of properly made lye-based soap (no excess lye, no excess fat) ranges between 9.5 and 11.5 more or less. The true pH of a given soap will vary depending on the fatty acids in the soap.

You're using pH paper which isn't accurate and isn't sensitive enough even if it was accurate. So you're getting wrong information about your soap.

I have more about soap pH, measuring pH, etc.: Soapy Stuff
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People add a LITTLE BIT of citric acid to their lye solution to create sodium citrate. Sodium citrate is a chelator, a chemical that helps lengthen the shelf life of soap and also helps reduce soap scum in the bath. When people do this, they should also add a little extra NaOH or KOH to compensate for the amount of alkali consumed by the citric acid.

More about how and why to add citric acid to soap: Citric acid, Citrus juice | Soapy Stuff

More about chelators: What is a chelator | Soapy Stuff

More about sodium citrate as a chelator: Citrate | Soapy Stuff
 

Zany_in_CO

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So need to reduce the ph to about 8 or less.
While you can reduce the pH to 8 or less, you don't want to do that! :nonono:
The lower you go the more likely the batch will separate.

The normal pH of properly made lye-based soap (no excess lye, no excess fat) ranges between 9.5 and 11.5 more or less.
:thumbs:

Keeping the batch alkaline (well above neutral pH 7.5) rather than below that number insures keeps the LS from growning nasties. Nasties thrive in acidic environments. That's why we use preservatives in lotions and similar products at or below pH 7. With fully saponified and properly made LS, no preservative is necessary.

Although pH papers aren't accurate, they do come in handy for ball-parking your final product -- like when I used one to test the pH of foamers to make sure they were safe to use.

More about pH Testing

So the soap paste i made is already good to be diluted
It may or may not be "fully saponified".

The ZAP test isn't always reliable and the batch may need to sit for a couple of days until it tests neutral with phenolphthalien drops (which is what I use) or the clarity test. Don't rush this step if you're OCD about clear LS as I am. 😁

Clarity Test & Phenol Drops - Scroll down to Step #11

If you're doing dual lye LS with glycerin subbed for part of the water to make the lye solution.that may not be necessary.

think this is a silly question do tell me why?
It's an excellent question!
I love it when Newbies ask questions... we all learn from the discussion, veterans and Newbies alike! I'm off to read @DeeAnna 's links as well! :nodding:

Here's my TIP about diluting LS that you may find helpful: DILUTION
 

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