# Zap Test



## Elizabeth Driver (Jan 21, 2020)

Hi,  so I've read a few posts about zap tests.  I realize that the longer soap cures it should become more mild, and that the "zap" is definitely an immediate sort of zap.  So - my CP soap is 10 days old, and I was dying of curiosity, and tried my finger in some suds - no zap.  so touched my tongue to the soap - no zaps......so because I was insistent on finding a zap - I tried several other bars......holding my tongue on the soap for longer periods of time each time - so eventually I did find that the soap would eventually give me some tingling or burning sensation - and I ended up with a mildly irritated tongue.  So, I know this wasn't the right way to do this.  I just wanted confirmation -  because I immediately felt these batches must be all lye heavy - but there really was not zap - but would it be normal if you press your tongue on your soap to end up wth a tingling or burning tongue - I guess it could be a reaction to something else....I guess I'll just have to wait till the 6 week time frame and give another try.....but just touch the tongue to the soap - not press it into the soap?!!


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## Anstarx (Jan 22, 2020)

Soap is alkaline so I imagine if you keep licking-or just putting it there it could irritate your tongue, especially fresh soaps are more alkaline than cured ones. It's just like if you keep your tongue in vinegar or lemon juice.


Elizabeth Driver said:


> So, I know this wasn't the right way to do this. I just wanted confirmation - because I immediately felt these batches must be all lye heavy - but there really was not zap


I'm rather curious on why you felt the batch must be lye heavy if there is no zap? Zap test is used to test excess lye-no zap, no excess lye, not lye heavy.
And no I don't think a proper zap test should be done by pressing your tongue to the soap, touching should suffice.


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## BattleGnome (Jan 22, 2020)

Did you see this link?

A zap test is like putting your tongue on a 9 volt battery. It zaps or it doesn’t. It is that immediate.

New soap can irritate skin even if it doesn’t zap. By looking for that zap you may have given your tongue the same/similar  irritation to using a fresh soap straight out of the mold (usually just red, itchy skin). You’d solve the itchy skin by washing with cured soap then putting on lotion. You might want to try rinsing your mouth then rolling a spoon full of oil to help coat your tongue


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## shunt2011 (Jan 22, 2020)

One, don't stick your tongue right on the soap. Two, just wet your finger and run it on the soap a bit then tough the tip of your tongue.  You'll know it if you've been zapped.   Otherwise your soap is good to go and cure.   Welcome to the forum, since this is your first post please go over to the introduction forum and tell us a bit about yourself.


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## Elizabeth Driver (Jan 22, 2020)

Well thank you for your responses! I attribute some of this behaviour to my recent insane soap insanity - I cannot seem to stop thinking about soap - so it was foolish and I did rinse my tongue after I realized it was burning a bit.   I think I was making an effort to be 300% sure there was no zap - and then when I did wait long enough to feel a sort of burning feeling - I felt convinced that must be proof they might be lye heavy.....a sign of an impending zap.  But honestly, I did try ph strips - and im not sure of their accuracy - they all showed a 9/10 ph - which was different than the distilled water I used.  I also tried some red cabbage juice - which turned a nice blue. I have made soaps for a couple of years but it was not till this year that I seem to be having some kind of Soap fever & I cannot stop making batches of soap - I have 11 dozen batches in my spare room now - and what am I going to do with them?  Helppppp!!!  and the more I learn - the more I realize different things that can go wrong - but I've never had a lye heavy batch......I had no reason to believe any of the soaps would be lye heavy - I used soapcalc.net, they are olive oil 35%, coconut 25%, shea 20%, Cocoa Butter 8%, Avocado 6%, Castor 6%, with a 33% lye concentration, CP soap, and there were no issues with any of the batches........I do feel reassured that the overall soap could be an irritating substance......and that a lye heavy batch has to be an actual zap - Thanks!



Anstarx said:


> Soap is alkaline so I imagine if you keep licking-or just putting it there it could irritate your tongue, especially fresh soaps are more alkaline than cured ones. It's just like if you keep your tongue in vinegar or lemon juice.
> 
> I'm rather curious on why you felt the batch must be lye heavy if there is no zap? Zap test is used to test excess lye-no zap, no excess lye, not lye heavy.
> And no I don't think a proper zap test should be done by pressing your tongue to the soap, touching should suffice.


Wellllll.........after reading the way it sounds - its ridiculous.  I am an over worrier.  and I've gone soap insane.  and I wanted ABSOLUTE proof there was not zap.....so when I experienced a teeny tingle after a little while my natural urge was to doubt my soap - and even now I am resisting the urge to sneak and lick of all of the soaps again....omg.  my husband has commented there is soap stuff accumulating in the kitchen - I told him I am contributing to science!
Thank you for taking the time to provide some reassurance


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## shunt2011 (Jan 22, 2020)

PH strips are worthless in testing for excess lye.  Soap ph is going to be anywhere from 9-11.5 maybe somewhat higher.  That is why we do the zap test.  Most accurate way to know there may be an issue.   If you know it's lye heavy, don't zap test it for quite some time depending on how heavy it is.


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## JackofallShaves (Jan 22, 2020)

I tried the zap test for all my HP batches after a 1 hr cook(1 lb recipe) and I couldn't tell if I was being zapped. I think I need to buy a 9V battery and zap myself to have the right reference, lol.


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## jcandleattic (Jan 22, 2020)

JackofallShaves said:


> I couldn't tell if I was being zapped


If you couldn't tell, or it wasn't strong and immediate, you weren't getting zapped. 


Elizabeth Driver said:


> I tried several other bars......holding my tongue on the soap for longer periods of time each time - so eventually I did find that the soap would eventually give me some tingling or burning sensation


After that many 'licks' on the soap, I wouldn't be surprised that you got some tingling, however, I really doubt it was an actual zap. 
There seriously is no "guessing" if it's a zap. you will absolutely know it.


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## shunt2011 (Jan 22, 2020)

If you’re zapped you’ll absolutely know it.


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## KiwiMoose (Jan 22, 2020)

shunt2011 said:


> If you’re zapped you’ll absolutely know it.


True dat.


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## JackofallShaves (Jan 23, 2020)

Can some of the experienced folks clarify this for beginners like me? Is the zap totally a binary thing - you either feel it or you don't? Is there something like a mild zap that is indicative of the fact that additional cooking is required? (I only do HP).


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## jcandleattic (Jan 23, 2020)

JackofallShaves said:


> Is the zap totally a binary thing - you either feel it or you don't?


IMO yes, you either get zapped or you don't and you will definitely know if it's a zap.


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## cmzaha (Jan 23, 2020)

JackofallShaves said:


> Can some of the experienced folks clarify this for beginners like me? Is the zap totally a binary thing - you either feel it or you don't? Is there something like a mild zap that is indicative of the fact that additional cooking is required? (I only do HP).


For added reassurance, if you run your recipe through a soap calculator and you are sure you measured correctly had a superfat you will not have a lye heavy soap. Even if you stop cooking too soon and your soap zaps it will cure out and stop zapping. Soap is really quite forgiving with small misses. I have mentioned this in another thread, but soap poured at a thin trace, especially if not gelled can stay zappy for 72 hrs, so it really is better to test for zap after a few days.


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## KiwiMoose (Jul 12, 2020)

It feels like you stuck your tongue on a battery


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## DeeAnna (Jul 13, 2020)

I think of it as similar to a static shock on a dry winter day. The strength of the static shock can vary, but even a mild static shock is still immediate and startling. It doesn't take a few seconds to start, and it doesn't leave you wondering what it was.

Same thing with a zap.

If all you're wanting to confirm is whether your soap is skin safe or not, don't be in a great hurry to zap test. Let the soap bars sit a few days to a week at least before you test. And even if the soap is mildly zappy at that point, like Carolyn (cmzaha) said, it will very likely disappear by the end of the cure time.


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## RevolutionSoap (Dec 4, 2020)

I just ate a small bar of soap. Didn’t feel anything but an upset stomach. 

But seriously is there no other way to test it?


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## JoyfulSudz (Dec 4, 2020)

People are always saying my soaps look delicious, good enough to eat.  Maybe I should let them be my lye testers.


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## jcandleattic (Dec 4, 2020)

RevolutionSoap said:


> I just ate a small bar of soap. Didn’t feel anything but an upset stomach.
> 
> But seriously is there no other way to test it?


not accurately. There's no reason to "eat" a bar of soap for testing..  if you don't feel a zap the first time testing, then, there you have it. There is no zap and it's fine.


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## Peachy Clean Soap (Dec 4, 2020)

Im not happy about my soap from a couple of weeks ago HP' I noticed after I added my C-Milk I saw small white spots' I thought soap was to hot & cooked the thick coconut milk, I poured it into a mold & hoped someway the c-milk would fade as soap continued to cure. a week latter the spots didn't magically disappear but increased! I knew I defiantly couldn't give this soap away as Christmas gifts, after a few more days I decided to see if I could re-batch it thought i'd test a bar before cutting up the entire batch, as I was cutting the soap decided to test the little white spot I thought was over cooked Coconut-Milk? I got an Instant ZAP!! Oh My Gosh ( Lye-Spots ) Soap Is Lye Heavy!.  I was so upset' ugh I guess it happens no matter how hard we try' mistakes happen. Ive gone over my recipe & its seems fine' but  obviously it wasn't, I must of left out an oil!.  Here is a picture of my soap. I did read I could use it for soap detergent' but I didnt want to even try, I tossed it in the trash. Being dyslexic which I've worked hard to overcome, I'll still switch my numbers if i'm not watching it very close.


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## Shewearsfunnyhat (Dec 5, 2020)

This is a good tutorial on how to test for alkalinity.


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## Peachy Clean Soap (Dec 5, 2020)

Shewearsfunnyhat said:


> This is a good tutorial on how to test for alkalinity.



Wonderful tutorial.


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## Shewearsfunnyhat (Dec 6, 2020)

Peachy Clean Soap said:


> Wonderful tutorial.


His book Scientific Soap making is well written and informative.


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## Peachy Clean Soap (Dec 6, 2020)

Shewearsfunnyhat said:


> His book Scientific Soap making is well written and informative.


I looked on amazon to purchase it' found a few used ones w/ a reduced price.


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## The Efficacious Gentleman (Dec 9, 2020)

It's the age old question with testing - at what pH is it bad? Does a perfectly fine Castile have the same pH as a perfectly fine salt bar? Or are you testing for excess lye instead of pH? That's a useful test for seeing if a soap is safe. pH on its own does not tell you if it is safe (IE not lye heavy) 

The zap test is an easy, effective, and (when done correctly) totally safe method of testing for excess lye in soap


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## Peachy Clean Soap (Dec 9, 2020)

The Efficacious Gentleman said:


> It's the age old question with testing - at what pH is it bad? Does a perfectly fine Castile have the same pH as a perfectly fine salt bar? Or are you testing for excess lye instead of pH? That's a useful test for seeing if a soap is safe. pH on its own does not tell you if it is safe ( Is not lye heavy )
> 
> The zap test is an easy, effective, and (when done correctly) totally safe method of testing for excess lye in soap


So True' as i'm learning. Dr. Keven Dunn's video above @ end after all said & testing done on how to test if soap is lye heavy' he mentions at end of video to simply do the zap test & train our selves to be able to " feel the zap & taste if soap is lye heavy' (  I'v known about this zap test' never thought to apply it to older soap ) so I thought I'd put Docts theory to test! I had a loaf other then the "pictured one above" I was in Q. about & It works! I could feel just a ever so "slight-zing" & " taste was defiantly different",   Also Ive discovered why ive had a prob w/ my "heavy lye" as of late! one reason is my " super fat was to low & 2%" & my "Balance" was off on lye. As I continue on my Soap Journey I'm happy to report my last few batches have been in "Balance" regarding lye as the good Dr. Dunn refers to "weight" lol .


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## Shewearsfunnyhat (Dec 12, 2020)

The Efficacious Gentleman said:


> It's the age old question with testing - at what pH is it bad? Does a perfectly fine Castile have the same pH as a perfectly fine salt bar? Or are you testing for excess lye instead of pH? That's a useful test for seeing if a soap is safe. pH on its own does not tell you if it is safe (IE not lye heavy)
> 
> The zap test is an easy, effective, and (when done correctly) totally safe method of testing for excess lye in soap


 
From a chemical safety  perspective, chemicals (including soap) with a pH of 11.5 or higher are considered to be category 1 corrosive substances under the GHS. They cause irreversible damage to human skin. Most cold process soap has a pH of 10 or higher. This is why it's important to have a way to test for alkalinity in soap. Its important to know if your product is safe to use especially if you decide to sell or give it to friends.

Zap tests are ok. But, they only give you information about what is happening at the surface of your soap. The pH of the surface of the bar will change over time as its exposed to CO2. The pH of the inner bar will not change much because it's hard for a gas to penetrate a solid mass.


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## DeeAnna (Dec 12, 2020)

If I'm understanding you correctly, you're saying the reaction with CO2 is the only reason why the alkalinity of bar soap can change over time. It's certainly a factor especially at the surface of the soap, but it's not the only reason.


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## The Efficacious Gentleman (Dec 12, 2020)

That's why I made a point of saying that it should be done properly. 

And while I think that the GHS labels are very good and well managed in general (pretty certain there will be many exceptions) I am not sure that it's overly helpful to bring it in to it, for the following reason -

If a bar of soap has a pH of 11.5 I think something might have gone wrong and it is most likely lye heavy anyway. If a bar is not lye heavy and is in all other ways well made and a reasonable bar of soap, it is not very likely to be pH 11.5 or higher, based on the average soap being 9 to 10 on the scale. 

So with the accuracy issues of how most people would test, coupled with the margin of error for layperson in interpreting the results, I still maintain that the zap test, when done right, is the best way for the majority of people to ascertain if their soap is safe or not.


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## RevolutionSoap (Dec 12, 2020)

I'm going to give sample soaps to the neighborhood moms for when their kids are naughty.  Then they can tell me if the kids also get a little zap.    #oldschoolparenting


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## Shewearsfunnyhat (Dec 12, 2020)

Kevin Dunn has great instructions on how to do it properly in Scientific Soap Making. You can easily get the chemicals needed to do it at home. (Well mostly easy, reagent grade ethanol can be hard to find due to COVID). The most expensive piece of equipment is a scale that reads to 0.00 g. The procedure is line with what the large cooperations are required to do.


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## The Efficacious Gentleman (Dec 13, 2020)

Shewearsfunnyhat said:


> Kevin Dunn has great instructions on how to do it properly in Scientific Soap Making. You can easily get the chemicals needed to do it at home. (Well mostly easy, reagent grade ethanol can be hard to find due to COVID). The most expensive piece of equipment is a scale that reads to 0.00 g. The procedure is line with what the large cooperations are required to do.


I know this. But (and it is a very big but) how many people would actually do it correctly? I can guarantee that not everyone who talks about the pH of their soap has even read anything by Kevin Dunn, let alone follow the instructions. 

I'm not going to keep on flogging a dead horse here - I maintain (and you can certainly think otherwise if you want to do so) that of the two methods, the zap test is the most accessible for the vast majority of people and gives the important information - is my soap lye heavy or not.


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## IrishLass (Dec 13, 2020)

The Efficacious Gentleman said:


> If a bar of soap has a pH of 11.5 I think something might have gone wrong and it is most likely lye heavy anyway. If a bar is not lye heavy and is in all other ways well made and a reasonable bar of soap, it is not very likely to be pH 11.5 or higher, based on the average soap being 9 to 10 on the scale.



A very interesting tidbit from Dr. Kevin Dunn's book in regards to pH and lye-heaviness shows how the former is not necessarily a good indicator of the latter. The tidbit was data referenced from a dermatological journal citing the conclusions of Irritatation Index tests done on a number of commercial lye-based soaps. It turns out the least irritating soap out of the group of lye-based soaps tested was actually the one with the highest pH: namely Johnson's Baby Oatmeal soap with a pH of 12.35. The _most_ irritating in the study was Camay Gala soap with a pH of 10.36. Go figure! lol


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## Lonardlis (Feb 24, 2021)

Elizabeth Driver said:


> Well thank you for your responses! I attribute some of this behaviour to my recent insane soap insanity - I cannot seem to stop thinking about soap - so it was foolish and I did rinse my tongue after I realized it was burning a bit.   I think I was making an effort to be 300% sure there was no zap - and then when I did wait long enough to feel a sort of burning feeling - I felt convinced that must be proof they might be lye heavy.....a sign of an impending zap.  But honestly, I did try ph strips - and im not sure of their accuracy - they all showed a 9/10 ph - which was different than the distilled water I used.  I also tried some red cabbage juice - which turned a nice blue. I have made soaps for a couple of years but it was not till this year that I seem to be having some kind of Soap fever & I cannot stop making batches of soap - I have 11 dozen batches in my spare room now - and what am I going to do with them?  Helppppp!!!  and the more I learn - the more I realize different things that can go wrong - but I've never had a lye heavy batch......I had no reason to believe any of the soaps would be lye heavy - I used soapcalc.net, they are olive oil 35%, coconut 25%, shea 20%, Cocoa Butter 8%, Avocado 6%, Castor 6%, with a 33% lye concentration, CP soap, and there were no issues with any of the batches........I do feel reassured that the overall soap could be an irritating substance......and that a lye heavy batch has to be an actual zap - Thanks!
> 
> 
> Wellllll.........after reading the way it sounds - its ridiculous.  I am an over worrier.  and I've gone soap insane.  and I wanted ABSOLUTE proof there was not zap.....so when I experienced a teeny tingle after a little while my natural urge was to doubt my soap - and even now I am resisting the urge to sneak and lick of all of the soaps again....omg.  my husband has commented there is soap stuff accumulating in the kitchen - I told him I am contributing to science!
> Thank you for taking the time to provide some reassurance




Contributing to science  best answer ever.

Anyway, i need some enlightment too..
I am also not sure how the zap feels like. I tried to do zap test on my liquid soap and experience the same thing  it doesnt burn or anything but after a few seconds i can feel tingle and mild burning sensation on my tongue and bitterness. 
The ph of my soap is 9.4  so it should be fine i guess??
I dont know how the battery zap feels like and i desperately need an answer..  


Sorry if it's not related to CP soap. I was searching for zap test and this threas shows up.


Any help will be very much appreciated


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## Zany_in_CO (Feb 25, 2021)

Lonardlis said:


> I dont know how the battery zap feels like and i desperately need an answer..


The "zap" of a zap test is unmistakeable. "Tingling", "burning" and "bitterness" are signs that your soap is not done and you should rinse your mouth well and spit. If you are in doubt of whether or not your LS is ready to dilute, you can wait a day or two for it to finish saponifying. Soap has a way of doing its thing whether you help it along or not.

I'm not a fan of the zap test. It's a tool every soaping should have in their toolbox *only as needed*. Zap testing every batch puts you at risk of compromising your taste buds. I find using phenolphthalein drops to be certainly safer and also the most reliable. Even then, I may have to wait a day or two or three before diluting the soap. 

Read what Kenna of Modern Soapmaking has to say about zap testing here (scroll down):

*HOW TO pH TEST HANDMADE SOAP*


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## Babyshoes (Feb 26, 2021)

Zany_in_CO said:


> The "zap" of a zap test is unmistakeable. "Tingling", "burning" and "bitterness" are signs that your soap is not done and you should rinse your mouth well and spit. If you are in doubt of whether or not your LS is ready to dilute, you can wait a day or two for it to finish saponifying. Soap has a way of doing its thing whether you help it along or not.
> 
> I'm not a fan of the zap test. It's a tool every soaping should have in their toolbox *only as needed*. Zap testing every batch puts you at risk of compromising your taste buds. I find using phenolphthalein drops to be certainly safer and also the most reliable. Even then, I may have to wait a day or two or three before diluting the soap.
> 
> ...



Thank you for that article, it was fascinating!


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## Tara_H (Feb 27, 2021)

Lonardlis said:


> I dont know how the battery zap feels like and i desperately need an answer..



I don't know if this will help but I experienced my first 'zap' last night so will try to help with a description!

I got a tiny bit of the soap batter on a gloved finger, then wet my other fingers and rubbed them together vigorously so it was well mixed together.  I just touched the very tip of my tongue to a bit of the liquid and immediately got a very strong sensation, almost like the skin being gently pinched, along with a flavour that I would describe as lemony and metallic.

Trying the exact same thing this morning, none of those things happened, instead it tasted a bit sweet and a bit soapy, and the taste didn't hit for a second or two after I touched it.



Zany_in_CO said:


> I find using phenolphthalein drops to be certainly safer and also the most reliable.



Can you share more about how you use these?  I've seen a lot of people recommending them so have been trying to source some, but when I read more into it (including that document you linked) it seems that it will show as pink for anything over about 8.  Do you wait for it to stop being pink to count the soap as done?


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## Zany_in_CO (Feb 27, 2021)

Tara_H said:


> Can you share more about how you use these?  I've seen a lot of people recommending them so have been trying to source some, but when I read more into it (including that document you linked) it seems that it will show as pink for anything over about 8.  Do you wait for it to stop being pink to count the soap as done?


With normal LS the paste normally tests clear at the end of the cook. If not, keep cooking or just cover it and wait for a day or 2 or 3 to finish saponification. In the case of *Carrie Petersen's GLS*, (forward to the 5:00 marker) the batch tests fuscia right after becoming soap. Wait an hour and the soap tests clear. Read more here:

*PHENOLPHTHALEIN USE IN LS*


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## jjan (Jun 18, 2022)

Elizabeth Driver said:


> Well thank you for your responses! I attribute some of this behaviour to my recent insane soap insanity - I cannot seem to stop thinking about soap - so it was foolish and I did rinse my tongue after I realized it was burning a bit.   I think I was making an effort to be 300% sure there was no zap - and then when I did wait long enough to feel a sort of burning feeling - I felt convinced that must be proof they might be lye heavy.....a sign of an impending zap.  But honestly, I did try ph strips - and im not sure of their accuracy - they all showed a 9/10 ph - which was different than the distilled water I used.  I also tried some red cabbage juice - which turned a nice blue. I have made soaps for a couple of years but it was not till this year that I seem to be having some kind of Soap fever & I cannot stop making batches of soap - I have 11 dozen batches in my spare room now - and what am I going to do with them?  Helppppp!!!  and the more I learn - the more I realize different things that can go wrong - but I've never had a lye heavy batch......I had no reason to believe any of the soaps would be lye heavy - I used soapcalc.net, they are olive oil 35%, coconut 25%, shea 20%, Cocoa Butter 8%, Avocado 6%, Castor 6%, with a 33% lye concentration, CP soap, and there were no issues with any of the batches........I do feel reassured that the overall soap could be an irritating substance......and that a lye heavy batch has to be an actual zap - Thanks!
> 
> 
> Wellllll.........after reading the way it sounds - its ridiculous.  I am an over worrier.  and I've gone soap insane.  and I wanted ABSOLUTE proof there was not zap.....so when I experienced a teeny tingle after a little while my natural urge was to doubt my soap - and even now I am resisting the urge to sneak and lick of all of the soaps again....omg.  my husband has commented there is soap stuff accumulating in the kitchen - I told him I am contributing to science!
> Thank you for taking the time to provide some reassurance


You made me giggle lol


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## MickeyRat (Jul 13, 2022)

Well you didn't do it the right way.  Neither did I the first time.  However, we apparently have similar personalities.  I wanted to know how the zap felt early on too.  Here's what I did the first time.  I had read to leave the greasy goop on bowls and utensils for a few days to let it turn into to soap.  So, the day after I made some soap, I took a spoon with some saponifying batter on it and stuck my tongue to it.  It did feel just like licking the top of a 9 volt battery.

After 10 days, unless something is wrong, you probably won't get a zap.  Nowadays I do a zap test after the cure just to be sure.


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