Testing soaps ph level

[psfponies]

What is the best way to test your soap to make sure the ph level is at a safe level to use. I was gonna try and find some ph test strips wasnt sure if they were the best to use.

Kay

[topofmurrayhill]

pH strips are not nearly precise enough to test that.

If you use a typical lye discount (say around 5%) and the soap doesn't zap your tongue, it should be safe to use. Almost everyone gets by very well with that.

If you feel motivated to analyze your soap in more detail and you're willing to learn some chemistry and lab techniques, this book includes a procedure for detecting free alkali in your soap:

http://cavemanchemistry.com/scisoap.html

Edited July 24, 2010 by topofmurrayhill

[psfponies]

pH strips are not nearly precise enough to test that.

If you use a typical lye discount (say around 5%) and the soap doesn't zap your tongue, it should be safe to use. Almost everyone gets by very well with that.

If you feel motivated to analyze your soap in more detail and you're willing to learn some chemistry and lab techniques, this book includes a procedure for detecting free alkali in your soap:

http://cavemanchemistry.com/scisoap.html

I used the soap cal to figure my lye which was set at 38 for water % to oils. Guess I will have to try the zap test!

[topofmurrayhill]

I used the soap cal to figure my lye which was set at 38 for water % to oils. Guess I will have to try the zap test!

A zap test should do you.

Even though it's kind of misleading, calculators usually refer to the lye discount as "superfat." In SoapCalc it's set to 5% by default, which is fine.

[Reg]

I was too thinking that the test strips would not be a good test. My understanding is you have to wet the soap to make the strip react. But what is the ph of your water? If it's tap, it's either neutral or slightly alkaline. Reverse osmosis and distilled water tend to be more acidic, and so are a lot of bottled waters. I was wondering about the ph testing too, so thanks for posting the question! (I'll go check out the link now)

[topofmurrayhill]

My understanding is you have to wet the soap to make the strip react. But what is the ph of your water?

An even bigger question: what is the pH of the soap supposed to be? Even when properly made, soap is alkaline and the pH varies (roughly between 8 and 10) depending on what it's composed of.

[Reg]

An even bigger question: what is the pH of the soap supposed to be? Even when properly made, soap is alkaline and the pH varies (roughly between 8 and 10) depending on what it's composed of.

How alkaline does the soap have to be to actually zap your toung?

[topofmurrayhill]

How alkaline does the soap have to be to actually zap your toung?

I have no idea. Each point on the pH scale represents ten times the hydroxide concentration in solution, so it might not even be very easy to correlate numbers with tongue sensations.

Soap is alkaline because the soap molecules dissociate to some extent when dissolved in water, but I know you won't get zapped unless there's Na+ and OH- in excess of the fatty acids.

Edited July 25, 2010 by topofmurrayhill

[soapgirl10]

I use the 5% superfat too. :-) I like the calculator at:

www.summerbeemeadow.com