A soapy experiment, input needed

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Well-Known Member
Mar 13, 2015
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LaLa land aka L.A.
Hello all,

Today I tested my last batch of CP soap to see if it could be used. Since I share soap with family I wanted to make sure it was ready. It had stopped dropping weight.

First I cut to the center of a bar. It is still a little soft in the center/outside is nice and hard. Observed no liquid, DOS, oil slicks or holes on the bar. This soap did a partial gel but looks okay.

Did 4 tests:
  • zap-no zap but about a minute later a tiny bit of burning that I associate with the EO/FO blend (Brambleberry Pure Honey FO and Litsea Cubeba EO)
  • Tested it to wash hands with (good creamy lather, no drying or burning)
  • Dissolved soap in distilled water and tested using my pH test strips (tested at an 8 )
  • Using a pre-made 1% phenolphthalein in alcohol solution dissolved soap in distilled water and after pheno drops darned if it didn't turn dark pink/fuchsia!! :shock:

So I went over the recipe:
  • Castor 2.6oz, Coconut Oil 10.6oz and Olive Oil 29.1oz/H2o 16.07oz and lye 5.91oz
  • Verified my cure time (5 weeks today)
  • Made sure that I didn't accidentally get tap water/other liquids on anything I was working with.
  • Then I looked at the bottle of distilled water (large spigot type) and realized it was the last little bit in the bottle that I'd used.

Is it possible the plastic is leeching something into the water and therefore my soap/water solution is contaminated?

Had to test this further. Had no other distilled water on hand, knew tap would turn pink. Okay, here is the gross part. I took a center cut of a bar. On the left I used a drop of my own spit (ick but I needed something to test with) and on the other side I put a drop of tap water. Then I added a drop of the pheno solution. Instant pink on the tap water side, zero pink on the spit side.

Repeated this with a new soap sample and distilled water. Spit on one side and distilled water from the bottle on the other. Spit side was clear and distilled side was dark pink!

I am thinking the distilled water was somehow contaminated and that it caused a false positive with the pheno. I am curious what our soapy experts think about this.

  • Was this a reasonable testing process to rule out a drying and or lye-heavy soap?
  • Am I being overly paranoid after no zap? :crazy:
  • Has anyone ever used spit in their test to rule out lye-heavy soap with phenolphthalein solution before?

I'm going to go ahead and cure for an additional two weeks. Hoping that the center will harden up a bit more and just to have a milder bar. Thank you all for your time. Look forward to your thoughts.


Well-Known Member
Jun 6, 2015
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Somewhere West of the Rockies
Basically phenolphthalein is a rather ineffective way to test soap and yours if most likely fine. DeeAnn goes into it in this thread...

I tested my first few batches the same way, (or ways rather) but I've settled into just the zap now that I'm more familiar with lye zap from FO or CO bitter/salty/kinda but not really zappy.


Staff member
Feb 11, 2008
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Right here, silly!
It's pretty useless to test one's soap with phenol. Even if you conduct the test correctly, it is hard to judge the exact pH unless you have a really good eye for different shades of pink since phenol turns various shades of pink from 8.2 pH to 12 pH (which is the normal range for lye-based soap), is clear from 0 - 8.2 pH, and is also clear when over 12 pH.

If your soap is showing pink, there is nothing to be afraid of. Properly saponified, zapless, lye-based soap should actually test out somewhere in the pink zone. If it tests out clear, that's when I would worry, because it could mean that the pH is really high. Of course, it could also mean the pH is 8 to 8.2, but the only way to be sure it's one or the other is to do a zap-test....which is actually the better testing method to conduct anyway. :)

IrishLass :)
Jun 18, 2013
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Idaho, USA
Toss the phenolpthalien and pH strips. You have the only perfect safe/not-safe test right in your mouth. If it does not zap, it is fine.

exactly, soap is pretty easy to test for safeness with your tongue. I feel you are overthinking it and making it too complicated.
No need to cut into a bar either, it will always be a bit softer in the middle unless the soap is years old.


Well-Known Member
Feb 20, 2013
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"...Spit side was clear and distilled side was dark pink! I am thinking the distilled water was somehow contaminated and that it caused a false positive with the pheno...."

Oh, well, I don't know that I would jump quite so quickly to that particular conclusion. Not saying you're wrong, just that you didn't do sufficient testing to support your hypothesis. Wouldn't you want to test a bit of your distilled water (and your saliva) directly to confirm the pH of these liquids in their plain form? Perhaps the difference you saw was that the distilled water was neutral (pH 7) and your spit was acidic (pH less than 7)?

As far as the rest of it, I agree with the others. Putting phenolpthalein drops on solid soap -- or on liquid soap paste -- are not testing pH properly and furthermore a pink blush from phenolpthalein says NOTHING about whether the soap is skin safe or not.