oh no the zaps

[elurah]

On what day do you usually do the zap test? Honestly, I usually do it on the day of unmolding and cutting,24 hours after pouring my soaps and I usually don't have a problem, until today. (dun dun dun)

Here is the recipe:
Sweet Almond Oil 17.1 oz (25%)
Coconut Oil 76 15.05oz (22%)
Shea Butter 10.26 oz (15%)
Avocado Oil 8.89oz (13%)
Cocoa Butter 6.84oz (10%)
Olive oil 6.84oz (10%)
Castor oil 3.42pz (5%)

Superfat 6%
Water:Lye 2.5:1
Water: 23.34oz
Lye 9.34 oz

This is a new recipe in that I always tweak percentages a little bit every time I make soap. This recipe has more avocado oil and less olive oil than previous batches. I have been making soap with high % of butters (15-25%) and high percentage of SAO for about a year now. I check off every oil as I add it so I know they all went in.

Cooking Notes:
- only issue was that scale turned off for cocoa butter at 4oz because I had to chop off more cocoa butter from my 10lb block. I added an additional 2.8 ounces once the scale turned back on
- Scent was Rosewood Natural Blend 1.7oz, Virginian Cedarwood 1.7 oz, both from New Direction Aromatics. (This is my favorite scent, highly recommend; also smells great with Texas Cedarwood)
- Oils were about 90-93 degrees F, Lye water was 98 degrees F when I mixed
- Hand mixed three separate containers (additives I. kaolin clay, II, III. different pecentages of dutch process cocoa powder) for about 3-4 minutes each. It was very thin when I started pouring but it had that creamy mixed look of early trace with no oil shimmer on top. This is thinner than I usually go but I had issues with too thick a trace last week so I was being a bit more bold.
- Only other additive was about 6 drops of ROE to oils once temp was under 110F


20 Hours Later:

Unmolding Notes:
- There was a small amount of liquid around soap. I use a mylar plastic liner in an acrylic mold and this happens every now and then, liquid usually reabsorbs into soap over a few hours once unmolded. You can see some of that liquid on the top, it has since dried up.
- Soap is medium firmness (medium pressure would leave a dent) I was planning to cut it later this afternoon.
- Soap has a very light zap.
- !!!! I did not clean my mixing containers overnight and I notice this morning that the "soap" in the containers is very soft (paste consistency) and has a distinct zap.

So, what do you all think? I re-ran the #s and they look fine to me. I am wondering if I just didn't mix enough and had not reached trace yet. I was planning on cutting today and retesting the soaps in 48H. I also am going to get a pH meter just in case. Would love to know your thoughts. I'll admit I'm a little bummed because I love this scent and that was the last of my Virginian Cedarwood.

Also, I really love this recipe and the variations I have done with the high SAO/butters. Recommend trying it out if you are interested

 

[Arimara]

I'd say wait another day and check it again. Did this soap gel at all?

 

[DeeAnna]

You don't need a pH meter -- pH alone is not remotely going to tell you if a particular soap is lye heavy or not. I went into this more in this thread -- https://www.soapmakingforum.com/threads/confused-about-chemistry.78704/

I'm with Arimara -- the fact that you poured at light trace/emulsion and the presence of liquid on the unmolded soap is telling me the soap might have had a tiny bit of separation failure and/or overheated a bit (given the size and boxy shape of your loaf, that's entirely likely). When I encounter this kind of situation, the liquid is normally alkaline even if the soap is overall fine.

I really don't think this is a serious problem, so don't be bummed! Let it sit for a few days and check again. And even if it zaps in a few days, I'd still let it cure completely. A mildly zappy soap usually cures out to be fine, if you can be patient with it.

 

[elurah]

DeeAnna I remember reading that thread about testing pH and of course I forgot about it. I need to review the chemistry to remind myself about the distinctions between excess alkalinity and pH. It has been a while.

I ended up popping it into the oven on low heat for an hour to ensure/force gel, then cutting it. Cut it looks like regular soap, gelled, no crumbliness or chalkiness. I was planning to test again in a couple of days, but I ended up doing the zap test again on a cut piece and no zaps! What you said makes perfect sense. I will retest in a couple of days in a few different places to make sure all is well. Photos tomorrow

 

[Susie]

I always gel my soap. Which is a good thing considering that I routinely forget to wear gloves to cut my soap. I zap test on the cut bars also.

 

[DeeAnna]

"...I need to review the chemistry to remind myself about the distinctions between excess alkalinity and pH...."

Here's my attempt to explain this subject, hopefully in a way that will "click" for more people than not. I don't want to talk down to anyone, but I also know many people on SMF aren't chemistry geeks. Here goes --

A solution, for the purpose of this explanation, is water mixed with anything that dissolves in water.

The soap and water on your hands when you wash is an example of a solution. Vinegar is a solution. The mixture of sugar, water, and flavorings in soda pop is a solution.​

Any solution that has a pH of 7 (sometimes called "neutral" pH) contains the exact same number of OH- ions and H+ ions. When the pH is equal to 7, the OH- ions and H+ ions are able to float around freely and cancel each other out. When they "cancel out" or "neutralize", they basically form water --

OH- + H+ --> H2O​

If there are more OH- ions than H+ ions, the pH will be alkaline, meaning the pH number is above 7. Baking soda in water is an example of an alkaline solution with extra OH- ions. The baking soda releases the OH- ions and those OH- ions cause the pH to be alkaline.

If there are more H+ ions than OH- ions, the pH will acidic, with a pH number below 7. Vinegar is an acidic solution. The acetic acid in vinegar releases H+ ions. These H+ ions cause the pH to be acidic.​

It's pretty easy to get the impression that an alkaline solution always has too many OH- ions and an acidic solution always has too many H+ ions. But chemistry is tricky -- this assumption is not always correct.

Sometimes the OH- and H+ ions in a solution are exactly matched, but the pH is not 7 as you'd guess. Even though there are exactly enough H+ ions to cancel out the OH- ions, the solution mght still be alkaline or acidic when you test it with a pH meter.

Why does this happen?

It's easy to forget an important fact when thinking about pH. The OH- ions and H+ ions that make a solution acidic or alkaline never exist in a solution all by themselves. There are other chemicals floating around in every solution. Sometimes these other chemicals have "opinions" about what OH- and H+ ions can and cannot do.

The fatty acids in soap are chemicals with opinions. Being acids, they contain H+ ions. When their H+ ions are released, those ions can make a solution more acidic. But fatty acids are a special class of acids called "weak acids". Weak acids do not easily let go of their H+ ions. Fatty acids tend to hold onto some or all of their H+ ions.​

Sodium hydroxide (NaOH) is much less fussy. As a strong base (strong alkali), it lets go of its OH- ions so all of these OH- ions are free to float around in solution, looking for H+ or other positively charged ions to react with.​

This difference in behavior is the reason why there will always be more free OH- ions in a soap solution than free H+ ions. Even if the total amounts of these two ions are exactly balanced chemically, this situation looks to a pH meter as if there are more OH- ions than H+ ions.

The H+ ions that are bound to fatty acids do not contribute to the pH of the soap solution. In other words, the pH meter doesn't "see" these bound H+ ions.​

To make things more complicated, some fatty acids are more particular about holding onto their H+ ions than others are. That means soap made from various mixtures of fatty acids will not all have the same pH. The pH of chemically balanced soap will range from about 9 to about 11.5, depending on the kinds of fatty acids in any given soap. (And I expect some of the other ingredients we like to add to soap will also affect its pH as well, but that's another story.)

The smaller fatty acids (lauric, myristic) and the polyunsaturated fatty acids (linoleic and linolenic) tend to hold their H+ ions a little less tightly, so there are more free H+ ions and the pH of the soap tends to be a little lower.

Medium length fatty acids (stearic, palmitic) and monounsaturated fatty acid (oleic) tend to be a little more protective of their H+ ions. That means there are fewer free H+ ions available, so the pH of soap high in stearic, palmitic, and/or oleic acid tends to be a little higher.​

If you measure the pH of a soap solution, the answer you get will be a measurement of two groups of OH- ions.

One group is the free OH- ions. These are any OH- ions that are not balanced by corresponding H+ ions in the soap. The presence of any unbalanced OH- ions is undesirable -- they make soap "lye heavy" and will damage the skin.

The other group represented in the pH measurement is the OH- ions that are balanced with H+ ions provided by the fatty acids. These balanced OH- ions are fine, normal, and acceptable.
​

You cannot tell the difference between excess OH- ions and "balanced" OH- ions just by measuring the pH. A pH meter (or test strip or phenolphthalein drops or cabbage or whatever) cannot "see" the difference between these two kinds of OH- ions. The presence of excess OH- ions (excess or free alkalinity) can be measured, but not by a simple pH test alone.

​

I have not yet answered the question of "why can't you add extra acid to lower the pH and still have soap?" But I'm gonna take stop here and let folks digest (and give myself a rest!)

 

[elurah]

Thanks for the explanation, DeAnna, much appreciated.

Here are some photos of the cut soap from this morning. No more zaps, so I am in good spirits.

 

[IrishLass]

Thanks DeeAnna for that most excellent explanation. My "DeeAnna File" just got bigger.


IrishLass

 

[DeeAnna]

We're also getting into this subject in a related thread, so I thought I'd provide a link to that for those who are interested -- https://www.soapmakingforum.com/threads/confused-about-chemistry.78716/#post-820334