# citric acid



## catikit (Jul 13, 2011)

Still trying to lower the ph of my soaps here.I see you can add citric acid to liquid soap to do that.can I add citric acid to cp/hp soap bars? Desperate to get my soap below ph of 9.5/10. thanks for any advice!


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## soapbuddy (Jul 13, 2011)

You don't want to lower the pH too much. If you do, you will end up with oily, caustic mess. For a lower pH, you would be better off making a syndet bar,


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## catikit (Jul 13, 2011)

i want to make natural baby bars and in order to get them passed for trading (safety assessment) i need to get the ph below 9.5  No luck so far


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## IrishLass (Jul 13, 2011)

I agree with Soapbuddy- you will be better off making a syndet bar.

Lye based soaps are naturally alkaline with a pH of 9.5 to 10.5. and you cannot change the 'nature of the beast', if you will, without distroying the soap itself. It'll start breaking down into salt, oil, and water- that oily, casutic mess that Soapbuddy mentioned. A couple of soapmakers on another forum I frequent have tried it and ended up with icky, gloppy messes.

IrishLass


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## Guest (Jul 13, 2011)

Theoretically, it should be possible, so I am sure it's also possible in practice. Now, it may make the bar softer, but hopefully this obstacle can be overcome by tweaking the recipe. 

Yes, if you add too much citric acid, you will achieve a "mess", which it isn't caustic. Just greasy. 

My guess would be that whoever has tried and failed has used too much citric acid. We are trying here only to tweak the pH down *a little*.

It's not easy to find out how much citric acid to use. If you go by trial and error, you should 

Something else: I believe the citric acid must be added in a water solution and only after the soap is done. Which means HP or rebatch.


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## Lindy (Jul 13, 2011)

Where are you that you need it less than 9.5?  In most parts of the world Castille Soap (100% Olive Oil) is considered a baby's soap with a PH of 9.5 or higher.  I don't see a problem with your SA based on that.....


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## catikit (Jul 14, 2011)

Am in the UK. You dont think over 9.5 is going to be too harsh for a baby? - or can i measure harshness by its 'cleansing' number (i.e. keeping it down to 12-14 on the scale)?
Perhaps i should explore assessment via another chemist - who might allow a higher ph. All my soaps are coming out as ph 10 - and i have tried so many different ingredient combinations, different superfat %'s, superfatting with different oils....... My heart sinks every time i unmould a batch and test it 
Maybe i am worrying unneccessarily and ph of 10 will be fine with some safety assessors....


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## agriffin (Jul 14, 2011)

So you test the pH right after unmolding?  I would wait until it's done curing...the pH will have lowered a bit.  I think you'll be find if you do that.


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## Guest (Jul 14, 2011)

It's weird and unlikely that all the different receipes are all exactly 10. How are you measuring ?

And yes, if that chemist  said you must be bellow 9.5, you should also ask another one, before performing more guesswork.


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## catikit (Jul 14, 2011)

Well-sometimes 10.1 sometimes 10.2 etc- but there's only a fraction of difference.now that you mention it, that is odd eh? I'm using a digital ph reader. I dissolve a tiny bit of the soap in some warm water and then test that solution. I always test right after moulding but when I have then repeated the test after curing (4 or so weeks) it just comes out as the same ph as when unmoulded. Maybe I'm using the ph reader wrong.... When I put it in tap water it reads 7.7.


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## Guest (Jul 14, 2011)

I can't hurt to check the pH meter aswell and maybe calibrate it. PH meters are a long story ...

If you can't get it professionally checked, get your hands on some pH buffer solution (check the instructions manual) and see if the readings are accurate. 

Or you could simply get, two buffers pH 9 or 9.5 and 10 (since this is the pH range you are interested in).  

Even the tap water is indeed 7.7 (which sounds a bit much), pH meters often have a different error curve for alkaline solutions. 

And even if your pH meter has automatic temperature compensation, it's best to check at room temperature, instead of warm water.


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## catikit (Jul 14, 2011)

Fantastic.many thanks for the advice.fingers crossed!


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## IrishLass (Jul 14, 2011)

catikit said:
			
		

> Well-sometimes 10.1 sometimes 10.2 etc- but there's only a fraction of difference.now that you mention it, that is odd eh?



I, for one do not find it odd at all. That's just the nature of lye-based soap- it will always be alkiline, and if properly made, the pH measurements will always stay within a narrow range of pH- I've heard of some getting as low as 9.5 at the low end of the spectrum, but normally the measurements hover between 10 and 10.5 (for properly made soap). A fellow soaper on another forum that I frequent who has a chemistry background has repeatedly tested handmade soaps in a lab with properly calibrated equipment consistently gets readings only as low as 10 (and as high 10.5) no matter how old the soap, what ingredients were used, and how high or low it was superfatted.


IrishLass


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## catikit (Jul 15, 2011)

I calibrated my test meter yesterday then tested one of my soaps. It came out as 9.6. Am going to order a bottle of buffer solution today. Shld I get ph7 or ph10 solution? And how often shld I calibrate do you think?


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## Guest (Jul 15, 2011)

Buffers are required for calibration. Usually *two* solutions (for a two point calibration). 

It's unclear to me how you calibrated it without having calibration solutions. Unless you mean that you had it calibrated by somebody else ...



> And how often shld I calibrate do you think?


Depends on your device, usage and precision required. 

Usually every few weeks (for home use - in a laboratory they may do it every day). More often during heavy usage, or when best accuracy is required. Also, as your device ages, more frequent calibration may be required.


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## catikit (Jul 15, 2011)

oh i had a small sachet of buffer solution that came with the meter.
Thanks for your advice.


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## Guest (Jul 15, 2011)

I get it now. 

So you should buy the calibration solutions according to the usage instructions which came with your device. If you lost them, ask the vendor or search on internet.

And on top of that you should have some buffer with pH in the 9.5 - 10 range, to check the accuracy of your measurements. 

For example, you could use 2 buffers with pH 4.1 and 6.8 for calibration (according to te usage instructions) and 10 for checking.


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## catikit (Jul 15, 2011)

ok. sorry to be a pain, but i'm not sure i understand..... So do i need to buy 3 different buffer solutions? Blimey this ph business is a bit tricky.


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## Guest (Jul 15, 2011)

Depends on your device. I don't know what device you have. 

My previous example was just a guess, so that you know what to look for when reading the instructions manual for your device.

Well, what does your manual say about calibration ?


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## Lindy (Jul 15, 2011)

I just checked with some UK soaper friends and they said there is no such stipulations in place.  I would advise you find another Safety Assessor....


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