Even though this is a new thread, I started it in reply to the post in deodorant-antiperspirant thread in the General health section.
It is better to keep the forum organized; if people do not see it as a useful resource, they are less likely to be coming back
Here is the post to which I am replying:
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SoSick (Premier Veteran): It is real difficult to find good water these days that's a fact. I have had to work at it a bit. watch out for the flouride in your toothpaste too, and dental fillings.
Oleg, I have on the counter, some eggshells from breakfast this morning... I put them into a small jar, covered them with vinegar, and put the lid on the jar. I figure they are ok not going into the fridge because of the vinegar, kind of like pickles, I don't always need to refrigerate those... but how long do I let that sit there till you would consider it ready to use? Should I shake it a couple times a day?
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Reply:
The speed of chemical reaction depends on temperature of a solution, as well as the contact surface between the ingredients.
(pardon for stating an obvious fact from the high-school chemistry)
In my experience, if you shake the solution a couple times, then in a couple days it should be ready in summer time and 3-5 days in winter (my place is very cool in winter, as we use "Japanese heating" as a part of our green living)
If you forget to shake, then eggshells come to the top, lifted by the bubbles, which formed on their surface. In this case it may stay like that for a week and there would still be vinegar in a solution.
That is why in summer time I use 3-4 jars and in winter 6-7.
You shouldn't let it stay too long, though, as bacteria will form, siince eggshells have biological residue in them. It may even be so bad, that a cloudy film would form at the top.
Then I filter it through a fine steel mesh strainer and it is ready for use.
There should always be eggshells left after all vinegar is used up. This is a guarantee that there is no vinegar left in a solution.

Regarding the biological component, eggshells have a thin film on them, that is smth bacteria can feed on. It is possible to remove most of it from the shells of a fresh egg, but I soft-boil them, because I heard when you scramble, some cholesterol oxidizes and it does not do you any good.
That is why you shouldn't let the prepared calcium acetate solution to stay for longer than a day at room temperature.

With regards to tooth paste, I only use toothpaste without rat poison. Once I bought toothpaste from India (Neem), I assumed it was fluoride-free, since it was from a health-food store, but turns out it has rat poison. It was impossible to return it, since the tube was not sealed. And so I had to take a liberal amount of calcium acetate solution (from eggshells) into my mouth and only then start brushing. Since that time I am very careful in reading the labels.

hth:oleg