pH?

[WilsonFamilyPicnic]

So, we finally got our pH paper and phenothalien (on the same day!) and i tested the 4 batches we made 4 weeks ago....now, I was reading everywhere about testing to make sure your batches aren't "lye heavy"...all of our batches came out around 8-9ish, maybe 7-8ish on one batch....what pH are they supposed to be??? they weren't pH 12 and they didn't eat our hands off when we sat there washing and washing and washing and trying out each batch! so are they safe for family, friends and showering (not necessarily all together..)?

 

[Lane]

What color was your test paper when you got those readings? I have an entire roll of pH paper but no chart to compare it to. :cry:

 

[soapgardener]

Oh dear! If your pH paper is a light peach color the color changes may go like this:

7 light yellow
8 light green
9 green
10 dark green
11 dark green/brown
12 brown
13 dark brown
14 dark dark brown

Acidic substances will turn the paper into shades of orange to red

pH paper has some limitations.... it won't give a "true" reading. Try to shoot for 7. (the actual true pH will be higher - taken with a meter). 7 will tell you that you don't have any free lye in your soap and you're good to go. I would think that a pH of 8 or 9 with paper would be a bit drying. Some people just wet the surface of the soap and stick the paper on the wet surface. I scrape a tiny bit off of the soap and mix it with a tablespoon of water. I then dip the pH paper in this mixture.

 

[WilsonFamilyPicnic]

I thought we were shooting for 7, but I didn't know if 8 was in the acceptable range or not...

Lane, about your pH paper...it should have come with a chart to match color to....i'd call the company and let them know. pH paper can vary as to color and increments. some only test a very narrow range. ex. 7-10 and if its under 7 it doesn't change color.....

 

[Flynn]

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[Lane]

Lane, about your pH paper...it should have come with a chart to match color to....i'd call the company and let them know. pH paper can vary as to color and increments. some only test a very narrow range. ex. 7-10 and if its under 7 it doesn't change color.....

I believe it is narrow range? I don't know... I have gotten blue on it...never brown...

 

[Flynn]

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[Lane]

Hmmm... I got it at work where we have to test to pH of our sanitizing water... *sigh* My soaps have always passed the tounge test... I'm going to buy new papers right now... Where does everyone get theirs?

 

[soapgardener]

i don't think it's possible to get a neutral (7) pH with "soap".

I scrape a tiny bit off of the soap and mix it with a tablespoon of water. I then dip the pH paper in this mixture.

make sure you use distilled water for this--tap water will affect the results.

Hi Flynn,

You are correct. The pH of soap, taken with a pH meter, will be around 9.5 - 10 or so. pH paper is a little different. It can detect free hydroxide from the lye, but it can't accurately determine the pH of soap in an aqueous solution... the indicator gets tied up in a mycel. pH paper is convenient in that if there is no free alkali in the soap the paper will read "7". This is an easy way to estimate the amount of free lye remaining in soap during the curing process. During HP, the pH paper will read "14" at trace and "7" about an hour later once the cook is complete. A meter will read in the high 9s at this point. Hope this makes sense.

 

[Guest]

there are several other threads on this topic if you search for them. Many experienced soapers posted to them.

I personally don't use them, becuase they aren't all that accurate for bar soaps.