Post below was originally posted on my blurt blog.
https://blurt.blog/sustainable/@dynamicgreentk/making-water-soluble-calcium-with-rice-vinegar

Making Water Soluble Calcium

With Toasted Eggshells and (Brown) Rice Vinegar

Do not use White Vinegar!

I saved my eggshells from previous meals and tried to remove as much of the membranes as possible. I'm learning the process of removing the membranes is easier if you hard boil your eggs. I then broke the eggshells into ¼inch parts or smaller.

With my BBQ, I toasted my eggshells on the 'cool' side of my BBQ until they were tan to brown.

A Hot Plate or toaster oven works for this as well.

Toasting changes the physical properties of the egg shells. During the process of toasting, it is important to remove any further organic matter such as the membranes because it will cause the final WCA Solution to rot.

Toasting Process

I constantly stirred the egg shells in the frying pan, while gently blowing out remaining egg membranes. Constantly stirring the egg shells will prevent unwanted burning/blackening.

I knew they were done when they all were tanned or brown, and all the membranes were gone.

I sterilized a container with a non living vinegar and paper towels. Bottle Sans is used by most for jar sanitisation.

I then added one part egg shells to TEN parts Brown Rice Vinegar slowly in order to prevent a over-reaction from when the Vinegar reacts with the toasted eggshells.

Coral, is better and it doesn't need to be toasted

The chemical reaction between the vinegar's acidity and the alkalinity of the calcium, releases the calcium bonds until the vinegar is saturated.

By keeping the lids loose I allowed for the container to be breathable but using a paper towel with a rubber band or non air tight plastic lids are fine too.

I Labeled and dated the container.

It takes about 7 to 10 days using (Brown) rice vinegar.
Do not use white vinegar.

I then strained the vinegar with a hemp coffee filter, that was soaked in vinegar and boiled twice, into a sterilized container. Sealing the container with an air-tight lid. You can also use cheesecloth or a fine mesh material.

This will store indefinitely if done properly. With this patch in particular I don't like the smell. I feel I was not able to remove as much of the membranes as I would have liked to. A newer batch is in the works already.

This is one of many inputs that I will be using for an upcoming type of Compost called IMO4.

IMO4:

(Video from Chris Trump's YouTube channel.)

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