Marketing
One may prefer to base their choice of glass color on visual aesthetics, design, and packaging. Some winemakers choose a bottle based on the color schemes associated with the label design, or the choice may be based on a presentation that fits a given marketing goal. Occasionally, we even see red glass wine bottles! This seems to be driven by marketing. Flint/clear bottles may fit in this category because the clear glass displays the color of the wine, which could be considered a marketing goal. After all, presentation and sales are certainly an important aspect to the wine business, and this should certainly be a factor.
At 10% UV wavelength filtration, clear/flint bottles filter the least amount of light, resulting in more light damage than other glass colors. Since 10% isn’t really UV protection, wines bottled in flint/clear glass are meant for immediate use. Tests on white and sparkling wines bottled in flint/clear glass and trials show that citrus aromas in wines decrease and off-flavors increase after only 3.3 – 3.4 hours of exposure to fluorescent lights. During the tests the lights were placed significantly closer to the wine bottles than normal winery or display conditions, so the testing conditions were pretty extreme. On the other hand, sunlight has 4286 times the amount of UV-A radiation than fluorescent lamps, so sunlight would have increased the amount of cooked cabbage, leek, onion, and skunk aromas! Some grape producers use red glass wine bottles for packaging.
