I used regular apple cider vinegar. The lovely thing is that it is already at a 5% solution straight out of the bottle. Says so right on the label. The easiest source of Vitamin C is Fruit Fresh. Unless they have changed their ingredients it is powdered Vitamin C aka ascorbic acid. In that case it would take some calculation to make the solution the proper 5%. That was another reason that I ran with the vinegar I already had instead of buying the Fruit Fresh. I haven't made a proper measured solution from a powdered chemical and water since I had Organic Chemistry over 30 years ago.If I ever decide to do it, it will probably take a week of research to find the instructions for making a 5% solution. Well Ask.com can probably spit out the answer for me in about 2 minutes. It will be a week of poking at an unused part of my brain to understand the directions again.
One thing that the vinegar does help with on the super dark eggs: Because it takes off the brown the eggs are easier to candle!
I am surprised that eggs would survive dipping in pure vinegar (5% acetic acid) I would have expected making a solution with 5% vinegar. That is one cup vinegar added to water to make five quarts of solution.
