SUPER random question!

[kittywings]

Does anyone know if a soil testing meter (a metal one with 2 prongs) would work to test the ph of liquid soap?

I was just stirring my latest batch and wondered this.

The only thing I can think is that if it's too lye heavy and the meter is aluminum that it could react.... hmmmm. Can you tell that I don't feel like buying testing trips or the like?

ALSO, a second random question. Why is liquid soap "always" amber? It doesn't bother me, but I was just remembering a picture I saw the other day of someone's 100% coconut laundry soap and it was 100% clear and it got me thinking.

Anyway, it's just my morning brain working too hard, I guess!

 

[honor435]

I dont know, but heard that ph strips arent that accurate, do the tongue zap test!

 

[kelleyaynn]

I have to say, I don't understand why pH strips are considered so inaccurate. I get mine from a science supply company and they are pretty darn close to what a pH meter will read. There are many different types of pH test strips, so you need to get some that will indicate within the right range, and of course litmus paper is useless, but pH strips have got to be more precise than the zap test. If you are uncomfortable with pH strips then phenolphthalein seems like a reasonable alternative too. Better than getting zapped! :shock:

 

[kittywings]

I totally zap test my hard bars, but I guess sticking my tongue into the soap pot puts me off a bit....

 

[agriffin]

I have to say, I don't understand why pH strips are considered so inaccurate. I get mine from a science supply company and they are pretty darn close to what a pH meter will read. There are many different types of pH test strips, so you need to get some that will indicate within the right range, and of course litmus paper is useless, but pH strips have got to be more precise than the zap test. If you are uncomfortable with pH strips then phenolphthalein seems like a reasonable alternative too. Better than getting zapped! :shock:

I think...

They are considered innacturate because in order to test the ph of solid soap you have to add some liquid. Whether it's dissolving the solid soap in some water or putting a drop of water on the solid soap. Once you add water...this dilutes the soap lowering the ph. So it is not accurate. Also, the ph on the outside of a soap bar does not necessarily give you the whole picture of the complete bar.

I think. :?

I use a digital ph meter for my liquid soap. This is the one I have.

http://www.texashydroponics.com/shop/pr ... 387&page=1

 

[kelleyaynn]

I think...

They are considered innacturate because in order to test the ph of solid soap you have to add some liquid. Whether it's dissolving the solid soap in some water or putting a drop of water on the solid soap. Once you add water...this dilutes the soap lowering the pH. So it is not accurate. Also, the ph on the outside of a soap bar does not necessarily give you the whole picture of the complete bar.

I think. :?

Hmmm.. I see the reasoning. But.... To make the soap wet so you can use a pH strip isn't going to dilute the soap all that much. You have to do some significant diluting or concentrating to change the pH in a major way. Liquid pH indicators work in much the same way, and whatever you put in an indicator will get "diluted" somewhat. In any case, you are certainly going to dilute the soap at least that much when you use it. For our purposes, the pH strip is accurate enough. Once the bar is made, nothing will give you the pH range of the entire bar if it is not uniform (at least that I can think of) without destroying the bar. A digital pH meter for liquid soap is definitely the most accurate. But for bar soap, nothing is going to be perfect, and as far as I can see, pH strips are preferable to sticking your tongue directly on a potentially lye heavy bar of soap.

 

[carebear]

I don't know why they would be, but they've been SHOWN to be inaccurate.

 

[agriffin]

black=mine

To make the soap wet so you can use a pH strip isn't going to dilute the soap all that much.
Yes it does. Even if you just drop water on a bar of soap to test with a test strip it just mixes with that tiny bit of surface soap that the drop hits. That's a bunch of water to that surface of soap.

Liquid pH indicators work in much the same way, and whatever you put in an indicator will get "diluted" somewhat.
I meter my liquid soap when I am finished with it and it is diluted. It does not get more diluted when testing. I don't add more water to test.

Once the bar is made, nothing will give you the pH range of the entire bar if it is not uniform (at least that I can think of) without destroying the bar.
Correct- one reason why I don't see the point in using pH strips for bar soap.

A digital pH meter for liquid soap is definitely the most accurate.
Yes, that's why I use one.

But for bar soap, nothing is going to be perfect
I agree.

I don't think pH strips are accurate for testing bar soap and choose not to spend money on them.

With that said...I understand that some people don't like doing the zap test. For me it tells me what I need to know. And really...I don't do it often.

 

[judymoody]

I understand that some people don't like doing the zap test. For me it tells me what I need to know. And really...I don't do it often.

I love doing the zap test. Probably because I haven't been zapped yet! Call me weird but I find tasting the soap interesting. And sometimes awful. Tea Tree Oil, yuck.

 

[soapbuddy]

I use a digital ph meter for my liquid soap. This is the one I have.

http://www.texashydroponics.com/shop/pr ... 387&page=1

Do the electrodes have to stay moist all the time? Do you need a calibration solution with it?