Very interesting thread. Here's a question for the experts:
I made my first batches of pickles last summer: pickling cucumbers in either white wine vinegar or red wine vinegar. They turned out extremely tart. At the time, I remember reading that you had to use vinegar with at least a 5% acidity.
I've since seen a lot of recipes that call for a mixture of water and vinegar. This seems like it would produce a less tart pickle. But doesn't watering down the mixture violate the rule to pack the cucumbers in a liquid with 5% acidity?
Thanks!

Ah - you are asking the ever present acidity/food safety question that the Ball Blue Book and the USDA enforce absolutely strictly with no wiggle room. 5% acidity is the golden rule of canning.
It is up to you.
The way I get around it with cucumber pickles is to make a 2 to 1 or sometimes a 3 to 1 ratio of vineger/water, bring all to a boil for ten minutes, pour into the loaded jar and go straight to the fridge so that I can live with myself, and still eat the pickle.
Now, even at 2 or 3 to 1 the USDA recommends an extended processing time for the canned pickles (various, depending upon wether you are doing a boiling water bath or canning under pressure, jar size, etc.) that actually cooks the cucumber in the process and has a detrimintal effect on crispness.
Two ways to get around that are to either lime the cucumbers in advance, or use a product called "pickle crisp" as an additive. The end result is a pickle that can be processed under heat that is sufficient to kill any bacteria, but will retain a crisp finish to the tooth, because of the addition of calcium to the pourous cucumber. It takes time and study. I am sort of a lazy pickler.
All that being said, gazillions of pickles were made using the "open kettle" method (that is, stuffing the sterlized jars with the raw veg, bringing the brine to a boil and boiling ten minutes, then filling the jar to overflowing and slapping a lid on it) for a very long time, over many generations and decades. They went into the pantry as soon as they cooled off enough to handle, and stayed there all winter, consumed on a regular basis.
Some of those folks died and were in the cemetary by 40 though, so who knows?