pH Testing w/ Strips

[lady-of-4]

Just thought I'd share this link on the accurracy of pH strips in the soap making. I know there is always a bit of debate in their use, so i figured I'd bring this up. I don't persoanlly use strips. I use drops. So, this isn't me being biased. It's from Miller Soap, and the article also includes some tips for how to gain a more accurate result when using strips. The tips are quite simple to follow. This can be applied to all forms of soap: bar, liquid and cream.

This will be posted in other relative sections of the forum, for ease of access for future reference, and newbies. If posting it more than once is not ok, just take the extras down and shoot me a message.

http://www.millersoap.com/phtome.html

 

[Jeanea]

I just received an order of the drops for ls. How do you use them for cp?

 

[lady-of-4]

Take a sample of your bar and drop directly on it. Bright pink is a high ph/lye heavy. Faint pink/can barely tell is perfect.

 

[new12soap]

I have posted that link to miller's site several times, but I really can't agree that phenolphthalein is all that useful either.

http://www.soapmakingforum.com/showthread.php?t=43328

 

[lady-of-4]

I have posted that link to miller's site several times, but I really can't agree that phenolphthalein is all that useful either.

http://www.soapmakingforum.com/showthread.php?t=43328

Phenolpthalein drops start their range of pink, at a pH of 8.2. The pink begins very faint, and brightens as the pH goes higher, thus making a faily accurate method of testing. Anyone who ask how to use the drops, i tell them simply, the lighter the pink, almost faint, the better. An ever so slight shade of pink is acceptable, since soap pH begins around 9, though some have managed to get lower than that.

http://en.wikipedia.org/wiki/Phenolphthalein


I do need to note, that a pH above 12 will cause the drops to become clear again. Now keep in mind, when using these on freshly made cold process, the drops will more likely be clear. That is not an indicator of neutrality! Therefore, it is best to wait until after you initial cure time to use them. If the color is still a bright pink, then allow to cure a little longer. Here I've provided a list of color indicator guides, phenol-p drops included, for future use. Use this ONLY if your seller didn't provide you one, like in my case. I have no guide, so I do a bit of guess work.

http://antoine.frostburg.edu/chem/senese/101/acidbase/indicators.shtml

Another indicator chart.... http://strehl-chemistry.wikispaces.com/18.5+Indicators
I noticed a lot of websites mentioned the drops also turn red, which can of course be confusing..it was to me just now! lol! So i just dug this chart up to show the color indications for not only the pink phenolpthailein, but also the phenol-RED drops. Just in case someone has the red ones instead.

And I looked at that last link and it mentioned red cabbage as a natural indicator and it totally reminded me of a link in a FB group, where the lady said she uses a red cabbage solution as her indicator! Here's the link she provided for anyone who'd prefer not to work with the chemical drops:

http://www.chemistryland.com/CHM107Lab/Lab1/Lab1PreparingCabbageExtract.htm

And another on red cabbage:

http://chemistry.about.com/od/acidsbase1/a/red-cabbage-ph-indicator.htm
http://www.chemistryland.com/CHM107Lab/Lab1/Lab1PreparingCabbageExtract.htm