# Soap tastes sour?



## divyadinesh07 (Mar 22, 2015)

My soaps have cured for 3 weeks and having done the taste test they taste sour, no zap.
Is it normal for them to taste that way or does it mean there is lye still in it?


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## Seawolfe (Mar 22, 2015)

The zap from excess lye isn't a taste, it's a feeling. If you have to ask, it's not zapping. 
Soap never tastes vey good :grin:


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## Susie (Mar 22, 2015)

^What Seawolfe said!  If you have to ask, it is not a zap.  Zap is unmistakable.


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## maya (Mar 22, 2015)

You'll know it if it happens.


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## dosco (Mar 22, 2015)

Zap is very similar to the feeling I get when I touch a 9V battery to my tongue.

-Dave


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## DeeAnna (Mar 22, 2015)

What the others,have said is spot on. If you find yourself wondering if it's a zap ... it's not.

Not zappy soap can have a range of tastes from bland or nearly tasteless to salty/metallic to pungent. 

Soap high in coconut can have a stronger taste than one with little or no coconut. That's why tooth soap usually has no CO in the recipe. 

Fragrance whether EOs,or FOs can also have a big effect on the taste.


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## lizard1232 (Mar 26, 2015)

DeeAnna said:


> Soap high in coconut can have a stronger taste than one with little or no coconut. That's why tooth soap usually has no CO in the recipe.



I have to ask, DeeAnna, how much soap are you eating that you know this? LOL


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## shunt2011 (Mar 26, 2015)

lizard1232 said:


> I have to ask, DeeAnna, how much soap are you eating that you know this? LOL


 
Right now I'm thinking too much.  :-D  Look at it this way, someone took one for the team.  Now we don't have to taste them.  Thanks DeeAnna.  :mrgreen:


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## Susie (Mar 26, 2015)

I don't know about y'all, but I zap test enough that I knew this.


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## shunt2011 (Mar 26, 2015)

I zap test but don't taste the soap.   I was just teasing anyway.   I've never noticed a difference but I also block my nose.  LOL  I think I ate enough soap as a kid and it brings back terrible memories.


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## DeeAnna (Mar 26, 2015)

Oh, gosh, you guys figured me out!!! Yep, I'm DeeAnna and I have a soap tasting addiction.


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## Dahila (Mar 26, 2015)

I had a bad day today, but now I am laughing , thank you people, thank you Deeanna


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## McSpin (Mar 27, 2015)

I've yet to put soap in my mouth and I'm really not planning on it anytime soon.  From what I've read, if the soap is aged, then even if you measure poorly, excess lye will eventually become inert with time, or something to that effect. 

I have so much soap, I'm sure every bar I use will be at least 3 months old before trying one.  So, let's say I measure poorly or forget an oil, what would be the worst thing that would happen if I washed 3 months down the road,  with a bar that was lye-heavy when I made it?


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## Susie (Mar 27, 2015)

Wow, you don't wait anxiously to test/use every batch of soap?  How do you resist?  How do you know what to change for the next batch?


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## The Efficacious Gentleman (Mar 27, 2015)

McSpin said:


> I've yet to put soap in my mouth and I'm really not planning on it anytime soon.  From what I've read, if the soap is aged, then even if you measure poorly, excess lye will eventually become inert with time, or something to that effect.
> 
> I have so much soap, I'm sure every bar I use will be at least 3 months old before trying one.  So, let's say I measure poorly or forget an oil, what would be the worst thing that would happen if I washed 3 months down the road,  with a bar that was lye-heavy when I made it?



But then if you're willing to take that negligible risk, why not take the negligible risk of zap testing?


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## shunt2011 (Mar 27, 2015)

I agree with TEG and Susie.


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## McSpin (Mar 27, 2015)

Susie said:


> Wow, you don't wait anxiously to test/use every batch of soap?  How do you resist?  How do you know what to change for the next batch?



After my first few batches, I used a bar within a week or two.  As soon as the first batch became 6 weeks old, I tried another bar and it was so different from week 1, that I figured testing withing the first few weeks was worthless to use as a basis for adjusting formulas.  I have at least 15 different recipes here that are aging where I haven't tested them because they are less than 6 weeks old.  I've made it a point to go a minimum of 6 weeks, so I can get a better opinion of my formula. I have a bastile (70% OO) that I don't plan to test until it's 4 months old. 

During the experimentation phase I'm going through, I have a list of things I want to try.  Each recipe has been carefully planned and made out in advance in Soap Calc.  I just add the date, and notes, when I make it.  In order to learn, I've taken the exact same recipe and made it at 2%, 5% and 9% superfat.  I've then taken the superfat % I liked best and changed and oil to see what happened.  I'm trying to learn the effect and whether it's a big one or a little one.  The problem isn't waiting the 6 weeks, it's figuring out where to stop, since the possible combinations are practically endless.


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## McSpin (Mar 27, 2015)

The Efficacious Gentleman said:


> But then if you're willing to take that negligible risk, why not take the negligible risk of zap testing?



Putting soap in my mouth has no appeal to me, but I would do it if I thought it was necessary.  If I was going to sell soap, I wouldn't trust that test. I'd use a pH test after 6 weeks to see where it was at that point.  If I cut a soap and it doesn't look right (pockets of liquid, or some other oddity), I'd be sure to test it right away, but since I have pH strips, that is probably what I'll use. I'm not saying that testing is a waste of time, just that I'm not putting soap in my mouth without a better reason.


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## FlybyStardancer (Mar 27, 2015)

Except that pH strips are a complete and total waste of time. Soap can't be measured accurately by those little paper strips (which are totally inaccurate anyways). Heck, even the aquarium hobby boards I've been on discouraged the use of strips because they're so bad (there's other tests on the market that are more reliable for aquariums).


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## McSpin (Mar 27, 2015)

FlybyStardancer said:


> Except that pH strips are a complete and total waste of time. Soap can't be measured accurately by those little paper strips (which are totally inaccurate anyways). Heck, even the aquarium hobby boards I've been on discouraged the use of strips because they're so bad (there's other tests on the market that are more reliable for aquariums).



You bring up a good point, and likely a potential problem.  I figured that "zap" testing was likely equally inaccurate.  At what pH do you feel the zap?  If that the same with everyone?  Does sensitivity differ to pH?  Do you lick the whole bar, or do you trust that the tiny spot you touched is representative of the whole batch?  If you get my drift, I'm suggesting that neither method is all that accurate and why I haven't bothered to test up until now.


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## shunt2011 (Mar 27, 2015)

Zap testing is the only way to check it in my opinion and many others. PH strips are not accurate on soap. 

Zap testing doesn't check the PH, it lets you know if you have active lye.

Soaps ph can be 8.5-13. I don't check my soap for zap until 3 days after unmolded. It can take 72 hours or more for total saponification to take place. I gel all my soaps so 3 days is long enough for min. If I get a zap I know there is likely a problem.


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## The Efficacious Gentleman (Mar 27, 2015)

I do wonder if ALL soaps could be 0% sf even though they were lye heavy to start off with, given enough time. I know there was the super lye heavy Castile experiment, but that had a huge amount of water. My thinking is that a water discount soap might not have enough to get all the lye migrated. Besides, at most you end up with a 0% sf soap at the end, which is not what you are expecting and so would spoil your results. You thought it was x recipe with y% sf but it isn't. You could think that a certain combination is rubbish when in fact you haven't even made that recipe. 

Zap testing is one of two methods for testing soap safety. The other requires lab equipment as you need to test for excess alkalinity. Neither of these test pH as pH doesn't tell you if you soap is safe or not. 

I don't mind if you zap test or not, but I have to set the record straight on the method itself. 

When I sell, I will continue to zap test, as I currently do. It is a safe, accurate and readily available test of the safety of my soap.


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## FlybyStardancer (Mar 27, 2015)

The zap test isn't testing pH... You can have zap or no zap at different pH levels. What the zap test tells you is if there's any unreacted -OH molecules left. The standard procedure is to get the tip of your finger a little bit wet, rub the surface, and then touch it to your tongue. If there is an excess of unreacted -OH, you WILL feel it. If you're really worried, the center of a cut side will be the most likely spot to give you a zap.

It's far more reliable than pH strips because besides being notoriously inaccurate, pH strips are physically incapable of measuring soap. If you rub a pH strip over a dampened bar of soap, it will measure the water on the soap, not the soap itself. (Not to mention that even if you had the best testing equipment and practices in the world, what might be a perfectly-safe fully saponified bar in one recipe would be too high a pH for another recipe, and we have no idea what's what.)


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## McSpin (Mar 27, 2015)

The Efficacious Gentleman said:


> I do wonder if ALL soaps could be 0% sf even though they were lye heavy to start off with, given enough time. I know there was the super lye heavy Castile experiment, but that had a huge amount of water. My thinking is that a water discount soap might not have enough to get all the lye migrated. Besides, at most you end up with a 0% sf soap at the end, which is not what you are expecting and so would spoil your results. You thought it was x recipe with y% sf but it isn't. You could think that a certain combination is rubbish when in fact you haven't even made that recipe.



Can't that be said of any recipe?  How do you really know you got everything right?  Just because it doesn't zap, doesn't mean you got the SF correct. 



> Zap testing is one of two methods for testing soap safety. The other requires lab equipment as you need to test for excess alkalinity. Neither of these test pH as pH doesn't tell you if you soap is safe or not.



It's been a long time since my college chemistry classes, but isn't lye caustic because it has a very high pH? Is there a pH level that would be considered unsafe?  Certainly a soap with a pH of 8, would not be caustic. Whereas one with a pH of 13 would not be something you'd want to use.   Can you have a lye-heavy soap with a low pH? Doesn't seem possible to me.  



> I don't mind if you zap test or not, but I have to set the record straight on the method itself.
> 
> When I sell, I will continue to zap test, as I currently do. It is a safe, accurate and readily available test of the safety of my soap.



If you read this over, you'll see that I'm not telling anyone to not lick their soap.  I'm simply saying it doesn't strike me as an accurate measurement of anything and that it's not for me.


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## FlybyStardancer (Mar 27, 2015)

McSpin said:


> Can't that be said of any recipe?  How do you really know you got everything right?  Just because it doesn't zap, doesn't mean you got the SF correct.
> 
> 
> 
> ...



While there is some variability in soap--we're working with agricultural products after all (the oils)--zap testing does show whether it's safe or not.

DeeAnna has talked until she's blue in the face about pH testing vs. excess alkalinity testing. Think of it this way--excess alkalinity is a square and high pH is a rectangle. Just because excess alkalinity = high pH, doesn't mean that all higher pHs are caused by excess alkalinity. What's dangerous to human skin is UNREACTED -OH. Once it's buddied up with something it likes (such as fatty acids), then it becomes harmless to our skin, no matter what the pH is.

Not to mention that soap is a colloid, and colloids are NOTORIOUSLY difficult to measure the pH of in the best of settings.

Here's some more reading:
http://www.soapmakingforum.com/showpost.php?p=433444&postcount=9
http://www.soapmakingforum.com/showpost.php?p=414542&postcount=22


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## McSpin (Mar 27, 2015)

FlybyStardancer said:


> Here's some more reading:
> http://www.soapmakingforum.com/showpost.php?p=433444&postcount=9
> http://www.soapmakingforum.com/showpost.php?p=414542&postcount=22




I got two things of importance from those threads.  One, figuring out the pH is tricky and knowing what it means is not straight forward. Two, time is your friend and if I'm waiting 3 months, then there is little to no risk of a lye-heavy soap. I'm very comfortable with my decision to not lick soap.

I do have a question for those with a chemistry background.  It appears that some of you have suggested that a soap with a very high pH of, say 13, would be safe if the lye was gone.  I find that hard to believe.  I would expect anything with a pH that high to be caustic.  Why would it not be?


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## cmzaha (Mar 27, 2015)

The Efficacious Gentleman said:


> I do wonder if ALL soaps could be 0% sf even though they were lye heavy to start off with, given enough time. I know there was the super lye heavy Castile experiment, but that had a huge amount of water. My thinking is that a water discount soap might not have enough to get all the lye migrated. Besides, at most you end up with a 0% sf soap at the end, which is not what you are expecting and so would spoil your results. You thought it was x recipe with y% sf but it isn't. You could think that a certain combination is rubbish when in fact you haven't even made that recipe.
> 
> Zap testing is one of two methods for testing soap safety. The other requires lab equipment as you need to test for excess alkalinity. Neither of these test pH as pH doesn't tell you if you soap is safe or not.
> 
> ...



I did the lye heavy test using default water of 38 percent. It still zaps. So it does take the extra liquid to carry the lye to the outside. I may be wrong with my assumption but I do know it ZAPS. I actually ended up recently salting ig out. Still hate the soap!


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## cmzaha (Mar 27, 2015)

McSpin said:


> I got two things of importance from those threads.  One, figuring out the pH is tricky and knowing what it means is not straight forward. Two, time is your friend and if I'm waiting 3 months, then there is little to no risk of a lye-heavy soap. I'm very comfortable with my decision to not lick soap.


 
After my yrs of soapmaking I was recently reminded why on should zap test  For some reason I had a facial bar go south and still zapped after 4 months. It is unuasual for that to happen since I very carefully measure all ingredients. This batch was not one of my normally low superfatted soaps and I was never able to figure what happened. I even rebatched if with added oil and it continued to zap. My opinion is, never trust soap


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## The Efficacious Gentleman (Mar 27, 2015)

McSpin said:


> Can't that be said of any recipe?  How do you really know you got everything right?  Just because it doesn't zap, doesn't mean you got the SF correct.



Very true.  But the zap test at least tells you that it is safe to use.  If one constantly mis-measures soap so that the SF is that far off, then there are far greater issues than working out which SF is best!



McSpin said:


> It's been a long time since my college chemistry classes, but isn't lye caustic because it has a very high pH? Is there a pH level that would be considered unsafe?  Certainly a soap with a pH of 8, would not be caustic. Whereas one with a pH of 13 would not be something you'd want to use.   Can you have a lye-heavy soap with a low pH? Doesn't seem possible to me.


 
I am no scientist, but the reaction would be involving free and UNREACTED -OH as Fly said.



McSpin said:


> If you read this over, you'll see that I'm not telling anyone to not lick their soap.  I'm simply saying it doesn't strike me as an accurate measurement of anything and that it's not for me.



No doubts, but as I often say, my replies are not only meant for one person, but for ALL people, which considering we are in the beginner section is important that people get a whole picture, both sides of an idea.


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## McSpin (Mar 28, 2015)

The Efficacious Gentleman said:


> I am no scientist, but the reaction would be involving free and UNREACTED -OH as Fly said.


From what I'm reading, OH can be contributed by more than just lye.  It can come from other ingredients and the concentration determines how caustic the soap would be. The more OH, the higher the pH.  So, how can a soap have no excess lye, and a pH of 12.5 or 13 and not be caustic?  Conversely, how can a soap with a pH of 8.5 have excess lye? Or, is it because the lye is in a pocket and the test simply wasn't from the right spot on the soap?  If so, you not only have to test the right spot for pH, but you have to be sure to lick the right spot.


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## DeeAnna (Mar 28, 2015)

I'm late to the conversation, so I'm just now catching up on the discussion this morning. I think all of you are making some good points. Here are some things that I have personally observed or have been observed by reputable soapers and I have concluded to be true about handcrafted soap in general:

A modest amount of excess lye will disappear with time to skin-safe levels in a "normal" KOH or NaOH soap, meaning one made with water typical for these types lye soaps. (Kevin Dunn's experiments with -5% superfat, my experience with soaps with a similar lye excess). 

An abundance of excess lye in a "normal" soap recipe is not likely to disappear to skin-safe levels. (cmzaha-Carolyn's experience with her "normal" soap, others' experience with "superlye" soaps with normal water content) 

An excess lye in a "high water" soap will disappear with time to skin-safe levels. (my and others' experience with "superlye" soaps with a high water content)

***

"... So, how can a soap have no excess lye, and a pH of 12.5 or 13 and not be caustic?..."

The short answer is that the pH measurement and being "caustic" (in the sense of excess alkali) are not the same thing. With the fatty acids typically used for soap making, the pH of a typical well made soap with no excess lye -- a "not caustic" soap -- will range from about 9 to about 11. 

I know soaps can have even higher pH values and still be skin safe. In one of my posts cited above, data from a reputable study shows a few commercial soaps with pH values ranging up to 12.4. The irritation index of these pH 12+ soaps was low enough that they would not bother normal skin, so obviously skin-safe soaps with pH above 12 do exist. I do not know why the pH is so unusually high in these particular soaps, but I have no reason to dispute the authors' findings. 

That said, the pH of most soaps used in this study ranged from 9 to 11, so I think it's safe to say the pH for most handcrafted soaps is more likely to be in the range of 9 to 11, give or take a bit.

***

Okay, so why can we use something that's clearly alkaline or acidic and not get our hide blistered off? 

When let loose in the normal world, strong acids and alkalis want to react with anything and everything they contact. That's just their nature. Anyone who has gotten a lye burn knows straight lye -- a strong alkali -- damages the skin quickly and deeply. In this circumstance, the only thing the hydroxide (OH-) ions from the lye can react with are the fats and proteins these ions encounter in the skin. Anyone who has gotten a burn from a strong acid such as nitric, hydrochloric, or sulfuric acid (raising my hand) knows the same is true for the hydrogen ions (H+) in the strong acid. 

The answer to moderating the harsh action of these strong alkalis and acids is the use of buffers, chemicals that acts as sponges, so to speak, for absorbing and releasing excess H+ and OH- ions. Buffers are able to placate hungry acids and alkalis so they don't harm our skin. 

The first sketch below is a rough example of the difference between a non-buffered mixture versus a buffered mixture. Don't hold me to any pH numbers here, folks, because the sketch isn't based on real data -- I'm just using this to give you a visual clue of what I'm talking about. 

In the unbuffered mixture, as you add acid, the pH drops immediately as a direct reaction to the added acid. The reverse happens as you add a base (alkali) -- the pH rises immediately in reaction to the added alkali.

Soap and the fatty acids from which the soap was made together form a buffered solution, so let's pretend the buffered example is a mixture of soap and fatty acid.

The "S" curve for the buffered solution shows that the pH doesn't change a lot between points 1 and 2. This is the region in which the soap and fatty acids are working well to buffer the pH of the mixture. 

As an acid is added to the soap-fatty acid solution, the soap breaks down into fatty acid. This causes OH- ions to be released to neutralize the extra acid. As a base is added to the solution, the fatty acid saponifies -- turns into soap -- and this causes H+ ions to be released to neutralize the extra alkali. This is the region in which the soap would be skin safe -- we're counting on the buffering action of the soap and fatty acids to protect our skin. 

Above point 2, all of the fatty acid has been converted into soap. As more alkali is added past this point, there are no more fatty acids to buffer the solution and "eat up" the excess OH-, so the soap becomes lye heavy and pH begins to rise sharply as more and more alkali is added. Above point 2, the mixture starts to behave more like an unbuffered solution. If you would wash with this lye heavy soap, your skin would end up being attacked by the alkali because there is no buffering action to protect your skin.

Below point 1, all of the soap has been converted into fatty acid. As more acid is added past this point, there are only fatty acids in the mixture -- there is no more soap to eat up the excess H+. The mixture starts to act like an unbuffered solution, and the pH begins to fall sharply.

When we make soap, our soap should ideally be mostly soap. We want it that way, because fatty acids (or fats) don't clean well. But we're playing close to Point 2 (the upper end) of that important buffered region. That means there is not a lot of extra fatty acid (or fats) in the soap to help buffer against extra alkali. But that's okay -- our soap will be skin safe -- as long as the soap mixture is still inside that buffered region.

***

My second sketch is an attempt to show that not all fatty acid and soap mixtures have the same relationship between pH and buffering. Some soap and fatty acid mixtures are properly buffered when the pH is a bit higher, others when the pH is a bit lower. 

The variability in the fatty acids in the fats we use for soaping AND the variability in handcrafted soap recipes AND the difficulty in accurately and easily measuring pH of soap all make it tough for a handcrafted soap maker to absolutely know "my soap is skin safe at X pH and unsafe at Y pH." Even in industry, where recipes and ingredients are more consistent and pH equipment and pH testing procedures are top notch, a direct pH measurement is not used for determining whether a soap is lye heavy or not.

Soap 1 might be a mixture of oleic and stearic acids and oleic and stearic soaps (say a lard soap). Looking at the pH at Point 2, I hope you can see Soap 1 will be properly buffered at a higher pH than Soap 2, which might be a mixture of lauric and myristic acids and lauric and myristic soaps (say a coconut oil soap). The pH at Point 2 for this soap is slightly less alkaline. 

That is why the pH is not really a sure-fire test for skin safety. You really want to know the answer to this question: "Is my soap safely within buffered region?" For an oleic-stearic soap, it will be safely buffered at a slightly higher pH. A lauric-myristic soap might not be buffered properly at that pH -- it might have a bit of excess alkali that would be harsh to the skin.

This whole thing about buffering and dealing with excess alkali is all helped by the cure period. It takes time for this complicated mixture of soap, fatty acid/fat, water, etc. to all sort itself out. It makes a lot of sense to allow a reasonable time for the soap to mature -- the cure period is not just about evaporating moisture.


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## FlybyStardancer (Mar 28, 2015)

Thank you, DeeAnna! That's an awesome explanation!


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## McSpin (Mar 28, 2015)

Thanks DeeAnna, I appreciate the effort you put into that post. I'm probably a bit dense, but I still cannot see how a soap with a pH of 13 would be safe.    

I understand the concept of the buffer, which will stabilize pH. I do not see how the buffer will make a pH of 13 (or 12.4) safe.  I'm trying to think of another substance that is buffered at an extremely low or extremely high pH that would be considered safe and I cannot.  Do you have any sources that back up or further explain this?


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## FlybyStardancer (Mar 28, 2015)

Maybe an analogy would help? I don't know if I'm shooting in the dark here, but it might help make sense of it.

Think of pH as speed and the buffering as the rate of acceleration/deceleration. Did you know that in victorian times, they thought that the humans would die if subjected to speeds of 25mph? We've since learned that the human body can tolerate some pretty extreme speeds (just look at how fast we're moving as the planet circles the sun!). It's the acceleration/deceleration where things can get tricksy. A high rate would be like a soap solution with little-to-no buffering power left--you get a big jolt and that can cause harm. However a slow rate of acceleration/deceleration lets your body adjust, just like having a large buffer cushion you from the effects of a higher pH.

That's not to say that high rates of speed aren't dangerous, and high pHs aren't safe in general either. But if you get a soap with a high pH and it has a high buffer in that area, then you're going to have a protective cushion that mitigates the effects of the pH.

And as DeeAnna pointed out, you're not going to find a lot of soaps that are safe at a pH of 13, but that doesn't mean that they don't exist. Or (probably more common in an inexpensive home setup) you could get a false reading of a soap saying it's that high when it's not.


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## Dahila (Mar 28, 2015)

I just tasted my two soaps and they are sour )) 
Thanks Deeanna


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## DeeAnna (Mar 28, 2015)

"...I do not see how the buffer will make a pH of 13 (or 12.4) safe. I'm trying to think of another substance that is buffered at an extremely low or extremely high pH that would be considered safe and I cannot. Do you have any sources that back up or further explain this?..."

I gather you are questioning whether any soap with pH of 12 or more can possibly be skin safe, but I'm not quite sure on what you are basing your objection. Why is a soap mixture at pH of 12+ ~not~ going to be skin safe, but a soap at pH of, say, 11 is? The pH scale is just a logarithmic measure of H+ concentration.

Setting my gentle questioning aside, I really do think the skin-safe soaps with a pH of 12 or more are not common, although obviously they do exist at least as commercially produced soaps. I'm not too sure what it would take to make a skin-safe handcrafted soap with a pH that high, if limited to the fats and other ingredients we typically use in handcrafted soap making. It's far more likely we handcraft soapers are going to make skin-safe soaps in the pH 9 to 11 range.

I don't have a list of resources that specifically discuss your question, so I can't help you there. The only thing I can share off the top of my head is that I do know there ~are~ buffers at high (alkaline) pH's and low (acidic) pH's as well as the middle range of pH, so high and low pH buffers certainly do exist. For example, solutions for calibrating pH meters are buffered mixtures, and calibration buffers are available from pH 1-2 ranging up to pH 13.


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## McSpin (Mar 29, 2015)

Maybe it's the definition of buffering that is getting in the way.  It appears that it is being said that buffering makes a pH safe even it is very low or very high.  I can't get my mind around that.  You can buy a buffered sulfuric acid for drain cleaning.  Buffering makes the pH stable, the acid less prone to a rising pH. It does not make it less effective at cleaning the drain as far as I can see.


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## DeeAnna (Mar 29, 2015)

Buffering is simply the property a particular chemical has of donating or accepting H+ or OH- ions in response to an external change in H+ or OH- concentration. Yes, basically it makes the pH more stable. 

The issue of "safety" is more about our human perception of what the buffering does to make soap better for our use.


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## McSpin (Mar 30, 2015)

So, what are the typical buffers in soap?  I would have guessed that it was the various fatty acids.


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## DeeAnna (Mar 30, 2015)

Uh, well, I thought I had explained that in post 33. It's the fatty acids and the soap made from those fatty acids. You can't have a buffered system unless both chemical species are present.


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## McSpin (Mar 30, 2015)

Sorry, I must have missed it, or wasn't paying attention since I assumed that would be the case. 

So, if I have a recipe that after 4 weeks, tests at 10.2 pH, on a regular basis, then it would seem to me that pH testing would tell me if a future batch of this recipe was safe, since if the buffer is used up and lye is present, the pH should be higher.


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## The Efficacious Gentleman (Mar 31, 2015)

If you could reliably test it, I would say so. Having a known benchmark of a recipe and making it in the same way (eg always distilled water) would be the only way that a pH test could tell you if your soap is safe. Otherwise you don't know just from the pH if it is safe or not. 

Which is why I zap test


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## McSpin (Mar 31, 2015)

I do have the equipment and supplies.  I have electronic pH meters, the calibration solutions and distilled water.  I think I will test all my soaps just to get an idea of how much pH actually varies with mine. If I have time, I'll purposely make a lye-heavy soap and then see what happens to the pH over time. I have close to 40 soaps sitting here from different recipes, so now is probably a good time to do this.


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