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Wine is a fragile product that’s susceptible to all sorts of problems, some of them trivial, but some cataclysmic, but most of which can ruin the enjoyment that wine makers intend.

Most of the bottles we buy look fine. Only in very few cases are there indications that the bottle has had problems.

Holding up a bottle of wine to a light source to see if it is spoiled usually reveals nothing. Red wines are often bottled in dark glass bottles, so any oxidation (browning) cannot be seen. And top-quality white wines likewise are bottled in glass with colors added, which is generally intended to protect the wine from spoilage.

One popular color, used for the best chardonnays, is called dead-leaf green. And it’s hard to see any browning through such color.

It has become popular in the last two decades to bottle certain early drinking whites in clear glass bottles (known in the industry as “flint”), but these vessels have their own issues.

With white and rosé wines, any bottles left in direct sunlight or in a refrigeration case illuminated by fluorescent bulbs are candidates to be lightstruck, which usually leaves the wine with slightly skunky or matchstick smell. (This is one reason beer is almost always bottled in dark glass bottles since beer is so susceptible to spoilage if bottled in clear glass.)

As a result, one basic rule is to keep all wine bottles out of sunlight.

Speaking of unwanted scents, cork taint (called TCA) once was a huge problem for the wine industry, but modern methods of making corks as well as marvelous advances in synthetics have reduced that issue considerably.

Although cork taint remains a problem, today it has shrunk to one of almost trivial proportions.

Then there is the issue of getting corks out of bottles. There are many kinds of corkscrews and cork pullers. The best is the so-called waiter’s corkscrew, with a helix for the screw itself.

This does a better job of extracting the cork than do single-piece, machined screws, which are often a disaster with older corks. They tend to strip out older corks from the center.

The so-called “ah-so” cork remover is a two-pronged gadget that works neatly with most older corks. For truly ancient corks, an expensive but brilliant device called the Durand is all but essential. It is a unique combination of the ah-so as well as a superior helix.

The screw cap, developed nearly 50 years ago by a forerunner of the French aluminum giant Pechiney, was widely used by Australian wineries in the 1970s, and has since become so well respected that virtually the entire wine production of New Zealand is now bottled under caps.

Screw caps have eliminated cork taint, but also have removed the romance of pulling a cork ceremoniously.

One additional problem that no one seems to talk about is the rare problem of screw damage. It is possible for the cap’s seal to be broken if the cap hits a hard surface. This could oxidize the wine.

To avoid this possibility, it’s best to buy only bottles with caps that have no dents.

Most people assume that a bottle of wine that shows it once leaked is to be avoided. That’s generally true, but I have had numerous bottles of sweet, desert wines that showed leakage yet were perfectly fine.

Dessert wines often leak. But if the fill level is high, the wine can very well be perfect.

A low fill level is an almost nonexistent issue, since today’s bottling lines are so sophisticated.

But older wines, including those bottled so long ago that the bottling equipment was imperfect, can have a lot less wine in them then the expected 750 milliliters. Thus the low field level, called ullage, is of major concern to auction houses selling older wines.

Catalogs published before a wine auction often will state what the ullage in a particular bottle is, such as “mid-shoulder fill.”

In such a case, an added note could very well be, “slightly stained label,” indicating the bottle leaked at some point.

Which is a red flag to experts, indicating that the wine may have been improperly stored, and spent some time at a temperature a bit too high, creating aroma and taste problems.

And yet a low ullage is not always a sure sign of problems. In 1985, I bought a bottle of 1932 Burgundy with a “very low shoulder” ullage, and it ended up winning a blind tasting with 10 other Burgundies from the same decade. In fact, it was sensational.

On a related packaging note, the giant cork company Amorim and a division of Owens-Illinois, the giant glass company, have developed a one-piece cork product called the Helix, a twist-off closure that has threads on the inside of the bottle to hold the cork firm.

The first wine company to use this product will be Bronco for use on wines under its Red Truck brand. The companies point out that the Helix is easily re-closable.

Wine of the Week: 2014 Ridge Zinfandel, Russian River Valley, Ponzo Vineyard ($32): This fabulous Zin is as Italianate as most Northern Sonoma Zins used to be before ultra-late harvesting became normal. Here the aroma is of tart plums and wild blackberries and a trace of oak. The entry is perfectly balanced with acidity (not for the faint of heart!) and the aftertaste is so well-designed for food it’s hard to imagine purists not buying large amounts. This is NOT a sweet wine. Ridge uses fruit from only one property in Russian River Valley. This wine exemplifies why. Not to be missed.

Dan Berger lives in Sonoma County, Calif., where he publishes “Vintage Experiences,” a weekly wine newsletter. Write to him at