Phenolphthalein as pigment

[Marten]

I searched the forum and found lots on the usefulness or uselessness of phenolphthalein as a pH indicator for Soapmakers. But what I wonder is... Has anyone has ever made use of its pretty magenta color to make it a pigment in your soap. And I wonder how this color changes or doesn’t with saponification.

What gave me the idea is that I use a yellow mica from Brambleberry which simultaneously functions as a pigment and an unofficial pH indicator as a sort of side effect. That is to say, it starts out orange in the soap batter, due to high alkalinity, but morphs into a nice golden yellow as the batch saponifies and becomes less alkaline.

 

[msunnerstood]

I don't think so, it's toxic

 

[Marten]

I see now it’s carcinogenic, at least when taken internally. It used to be a common laxative.

 

[xavalyss]

I use a yellow mica from Brambleberry which simultaneously functions as a pigment and an unofficial pH indicator as a sort of side effect. That is to say, it starts out orange in the soap batter, due to high alkalinity, but morphs into a nice golden yellow as the batch saponifies and becomes less alkaline.

This is interesting to me. Just awhile ago I put a batch to bed that I used a yellow mica from Brambleberry (had a longer name that isn't at my fingertips at the moment) My plan was to have a nice yellow base with an uncolored base reverse swirl and an orange swirl. I was sad that it went all orange. I hope that magic morph happens.

 

[Marten]

Buttercup Mica. Yeah it’s normal. You’ll know when it’s mostly saponified as all that gross orange turns nice and yellow.

 

[DeeAnna]

I give a big thumbs down on phenophthalein as a colorant. Not a good idea due to toxicity, although I agree the magenta it makes is a pretty color.

 

[Marten]

Thanks DeeAnna.

 

[xavalyss]

Yes it's Buttercup mica. Keeping my fingers crossed.

 

[Zany_in_CO]

I searched the forum and found lots on the usefulness or uselessness of phenolphthalein as a pH indicator for Soapmakers. But what I wonder is... Has anyone has ever made use of its pretty magenta color to make it a pigment in your soap. And I wonder how this color changes or doesn’t with saponification.

Interesting question. With all due respect to @DeeAnna's take on Phenolphthalein's use in soap, this might be an interesting experiment.

Phenolphthalein (1% solution in alcohol) is used in liquid soap to test the pH level in the paste prior to dilution. Many LS'ers use this technique. Personally, I've found it to be the most reliable way of testing the paste before diluting. But that just me. I stick a knife into the paste, pull it out, and put a drop of 1% phenolphthalein on the bit of soap. If it tests clear, then I know I'm good to go. What's interesting is, when I put the knife in 16 oz. or so water to soak, it turns the whole glassfull a brilliant fuscia pink. Pretty! Since Phenolpthalein turns the paste clear at pH 9.5-9.8 it is conceivable that bar soap with a higher pH would hold the fuschia color. Or not. LOL Dunno.

PHENOLPHTHALEIN
https://www.soapmakingforum.com/threads/phenolphthalein-use-in-ls.77349/#post-801250

 

[DeeAnna]

"...this might be an interesting experiment. ..."

Phenolphthalein is a toxic chemical that happens to have a pretty color. Toxicity overrules pretty every time, so don't encourage risky behavior.

If a person uses it as a pH indicator, phenolphthalein should be added to a sample of the product. The sample should be discarded after testing is done. Never add phenolphthalein directly to product.