Recipe: How to Make Vinegar from Wine (repost)

This is a repost.
I have not made it, but this is some information.

MAKING VINEGAR FROM WINE
If you make wine (as oppesed to apple) vinegar, you can dispense with the apples and the press. You'll want good quality wine that's not too strong -- 10-11% alcohol -- because too much alcohol inhibits the activity of the bacteria that transform the wine. If the wine is too weak, on the other hand, the vinegar won't keep well.

There are several ways to proceed.

The simplest is to leave an open, 3/4 filled bottle in a warm place for a couple of weeks.

This technique yields just one bottle, however. For a steady supply of vinegar, take a wide-mouthed glass jug whose capacity is at least a gallon and pour a quart of wine and a cup of vinegar into it. Keep the container covered most of the time, but open it for a half hour every day. In a couple of weeks the madre, a viscous starter, will have settled to the bottom of the jug, while the vinegar above it will be ready for use. Add more wine as you remove vinegar to keep the level in the jug constant.

If you want to make wine vinegar in larger batches, procure a 1-gallon (5 liter) cask that has a spigot at one end. If it's new, rinse it with vinegar and let it dry. Next, fill it to within a couple of inches of the top and put it, uncovered, in a place that's about 68 degrees F (20 C). In a couple of weeks the wine will be vinegar. Drain it from the cask using the spigot, and, if you can, bottle it during a waning moon because it will be clearer. Replace the vinegar removed with more wine, pouring it into the cask with a length of hose so as to leave the surface molds undisturbed.

As was true for apple vinegar, homemade wine vinegar will be more delicate and have greater depth than commercially prepared vinegar.