Best way to measure water? And pH?

[CastileAway]

I'm trying to measure the pH of a finished lotion and I'm unsure how to do it. I have liquid pH tester, but not sure if that is accurate with a lotion that already has some color to it (tan). I also have strips, but since it's a finished lotion it doesn't absorb into the paper strips.

Any tips?


The other thing I'd like to know is how to properly measure a water phase that has an ingredient in it. So as to say, I'm adding rice powder to the water phase as a thickener. However, when heating water naturally some of it will evaporate away. So if I start with the amount of water I need, I won't have enough at the end. If I start with more than I need and don't use all of it for the lotion, then I can't accurately measure the amount of rice powder I want to use. Meaning, if I need 1 oz of water and start with two oz of water and 1% (of entire lotion formula) rice powder and it evaporates down to 1.3 oz, that means the 0.3oz I discard contains some of the rice powder I wanted. Resulting in less than 1% rice powder in the final formula, not to mention a different amount every time I make another batch.

So what's the best way to do this?

Start with an amount of water that will evaporate down below the one amount I want and have a separate pot of heated water? Such as, if I require 1 oz of water I'll start with 1.5oz of water and add the rice powder. As an example, it may evaporate down to 0.8 oz, but my 1% rice powder should remain. Then I just add an additional 0.2oz before I mix the water phase with the oil phase.

????

And how about when using Hydrosols in place of water? If I have to heat it to 170 degrees and maintain that for 20 minutes, that's a lot of Hydrosol evaporated and wasted away.

 

[carebear]

if you lose too much water simply have some on the side (held at the right temp) to add in at or toward the end of that step.

if you are measuring by weight it shouldn't be an issue.

re: hydrosols - did you ever try covering the container in which you are heating them? a simple watch glass is a great tool because it's clear and as it's convex (from the outside/bottom) the condensation drips back in... http://en.wikipedia.org/wiki/Watch_glass
(better picture: http://chemistry.about.com/od/chemistry ... -Glass.htm)

 

[CastileAway]

That's what I figured and that's what I did. Thanks.

As for the Hydrosols, would a watch glass really hold in the liquids? Just seems that at 170 degrees for 20 mins, pretty much everything boils away. Plus, I heat it in a pot. Do they have watch glasses for pots?


Anyone have any recommendations about the pH problem?

 

[carebear]

yes

and no

and no

 

[CastileAway]

What do you use the watch glass over then?

 

[carebear]

I use a beaker in a pan for a double boiler. I also often heat things in the microwave with a watch glass over them, and ALWAYS keep some sort of cover over open beakers on the bench.

 

[CastileAway]

Do you use something to hold the beaker above the pan surface?

Or do you just place it in the pan with some water?

 

[carebear]

I have it up on a little steamer rack that fits flat in the bottom of the pan. Be careful though that the watch glass doesn't extend too far over the edge of the beaker or you can end up collecting condensation from the steam in the double boiler (not necessarily a bad thing if you are losing water anyway LOL)