Zany_in_CO
Saponifier
From my Files - This is a quote from Steve Mushynsky, Owner of www.summerbeemeadow.com and long-time member of the Liquid Soaping Yahoo Group which is soon to be Defunct. He explains why Pheno drops or, as he says, "Phenol P", works as an indicator for excess lye in LS. I quote his post in its entirety here for those interested in using Phenolphthalein to test their paste before dilution.
HTH
Phenolphthalein is an indicator that changes color at a very specific range of pH levels that happens to be perfectly suited for liquid soapmaking. There is actually no difference between having 'excess lye in your soap' and your soap having too high a pH level as 'excess lye' would create a high pH level and having too high a pH in soap would be caused by 'excess lye'.
A very simple pH meter can cost $35 and up and requires purchase and use of standard pH solutions (cost for a set around $25) for recalibration each time the meter is used to be accurate. I can't discount the usefulness of having accurate pH readouts as I used one during a series of test batch pH evaluations that I did a while ago. It is, however, a bit of a bother to recalibrate the meter each time, and skipping this can result in the meter reading way off from being accurate.
On the other hand, using Phenol P correctly will give an easy, reliable result. Basically. if the test solution is clear or just ever so slightly pinkish, the soap's pH is 9.5 or less. If the test solution is distinctly pink or red when a drop of Phenol P is added, then the soap test solution is higher than 9.5 pH and can be brought down a bit with a weak borax solution addition. It's an easy simple way to test for acceptable pH level in LS.
As to what pH you'd want your liquid soap to be, I found that levels of 9.5 to 9.3 at the lowest are generally ideal for liquid soaps containing some coconut and some oleic-containing 'soft' oils also. Any less than this and they are very prone to clouding due to too low pH or upon addition of fragrance. This was after doing a lot of test batches, each measured laboriously with a recalibrated meter. Inasmuch as this 9.5 to 9.3 range is exactly the range where Phenol P works, I no longer use a meter for any production batches. Phenol P works just fine instead.
By the way, different oils produce different liquid soaps that can tolerate different pH levels. Olive oil liquid soap can cloud if brought to below 9.5 pH, whereas pure coconut or castor liquid soap can be brought to around 8.5 ph without clouding. This means that while coconut based soap is generally considered to be a bit harsh, it's ability to be made at a lower pH can counteract this, as lower pH's are themselves less harsh to the skin. If one were to push a high-coconut or castor soap toward an 8.5 pH level, one would then want to use a meter, as this is below Phenol P's useful range. Unfortunately, such soaps produce an undesirably water-thin resulting product, so it wouldn't come up often.
HTH
Phenolphthalein is an indicator that changes color at a very specific range of pH levels that happens to be perfectly suited for liquid soapmaking. There is actually no difference between having 'excess lye in your soap' and your soap having too high a pH level as 'excess lye' would create a high pH level and having too high a pH in soap would be caused by 'excess lye'.
A very simple pH meter can cost $35 and up and requires purchase and use of standard pH solutions (cost for a set around $25) for recalibration each time the meter is used to be accurate. I can't discount the usefulness of having accurate pH readouts as I used one during a series of test batch pH evaluations that I did a while ago. It is, however, a bit of a bother to recalibrate the meter each time, and skipping this can result in the meter reading way off from being accurate.
On the other hand, using Phenol P correctly will give an easy, reliable result. Basically. if the test solution is clear or just ever so slightly pinkish, the soap's pH is 9.5 or less. If the test solution is distinctly pink or red when a drop of Phenol P is added, then the soap test solution is higher than 9.5 pH and can be brought down a bit with a weak borax solution addition. It's an easy simple way to test for acceptable pH level in LS.
As to what pH you'd want your liquid soap to be, I found that levels of 9.5 to 9.3 at the lowest are generally ideal for liquid soaps containing some coconut and some oleic-containing 'soft' oils also. Any less than this and they are very prone to clouding due to too low pH or upon addition of fragrance. This was after doing a lot of test batches, each measured laboriously with a recalibrated meter. Inasmuch as this 9.5 to 9.3 range is exactly the range where Phenol P works, I no longer use a meter for any production batches. Phenol P works just fine instead.
By the way, different oils produce different liquid soaps that can tolerate different pH levels. Olive oil liquid soap can cloud if brought to below 9.5 pH, whereas pure coconut or castor liquid soap can be brought to around 8.5 ph without clouding. This means that while coconut based soap is generally considered to be a bit harsh, it's ability to be made at a lower pH can counteract this, as lower pH's are themselves less harsh to the skin. If one were to push a high-coconut or castor soap toward an 8.5 pH level, one would then want to use a meter, as this is below Phenol P's useful range. Unfortunately, such soaps produce an undesirably water-thin resulting product, so it wouldn't come up often.
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