What I find most disturbing in writing about filtration (of wine) " writes a reader of this column, "is that it is unfair to reader-consumers, taking advantage of their impressionability." Nowadays, he says, the mere mention of filtration prejudices some people against a wine. "They imagine that differences in quality exist between a filtered and an unfiltered 'fine wine' because they think beforehand that some must exist," he continues, and cites several well-known enologists, among them Jean Ribereau-Gayon: "Only in considering the extreme cases is filtration dangerous for very good, bouqueted fine wines."

Filtration is still debated on both sides of the Atlantic. Some critics have called filtration a moral and technical outrage. It is all part of the larger argument over "meaty" wines, as oposed to lighter, cleaner, brighter ones, and it affects the marketplace in ways you might not imagine, including cost and availability of good wine. The trend toward less substantial, more uniform drinking is characterizeded by what California marketers call "elegant" wine, or "food wine," that inelegant redundancy. Many such wines have indeed been stripped of their more interesting characteristics, if they had any in the first place, but the real culprit is not filtration.

"Properly done," says Andr,e Tchelistcheff, enologist and grand old man of California pinot noir, "filtration doesn't take the guts out of a wine" -- guts being the tannins that allow red wine to age, the extract that gives it added flavor and the tiny color particles. Most producers of California's better wines lightly filter them after fermentation to remove some of the particles that would fall out later anyway as sediment. "It's a shock to the wine at first," says Linn Briner, assistant winemaker at Mayacamas Vineyards,t they bounce back."

"An unfiltered wine will taste meatier when it's drunk young," says Randy Dunn, winemaker at Caymus Vineyards, where reds and whites are filtered. "But over time the two wines will even out." "Americans don't like tons of sediment," says David Stare, of Dry Creek Vineyards, in Sonoma County, "so we rough-filter before aging in barrels, and again before bottling. It's unappetizing," he adds, "to find a dead fruit fly in the bottle."

Paul Draper, of Ridge Vineyards, says he rarely uses filtration, but "we are willing to do so if the wine is unstable. Filtration's not necessarily a negative if it's done after the wine has gained some complexity." Centrifuging before fermentation, a common practice, is a great enemy of complexity. So is heavy "fining," the adding of components like Bentonite, egg whites, gelatin, powdered charcoal and various chemicals that bond with unwanted elements then fall out of solution. "Fining can strip a wine a lot faster than filtration," says Draper.

Excessive fining is really the means by which many vineyards produce less tannic, less complex wines without long life expectancy, on grounds that the consumer wants to drink them sooner and doesn't want to have to think about them too much. Many of these "food wines," these "elegant" nonentities, are made from grapes without the potential for great wine, but are sold at great wine prices. They have been stripped and then tightly filtered under pressure to make them shine in the restaurants' artificial light. Lack of character means easier matching with food, since innocuous wine goes with most anything. They are not bargains; they represent a lamentable stereotyping in an industry that needs its individuality, but we can't blame it all on the filter.