Is UV-blocking glass or film enough to protect a wine cooler? Or does the amount of visible light transmission (VLT) matter too?

Ask Dr Vinny

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.

Dear Dr. Vinny,

In a previous question, you recommended putting UV-protective film on a wine refrigerator to further protect it from sunlight. Is UV blocking enough? Or does the amount of visible light transmission (VLT) matter too?

—Jason, Washougal, Wash.

Dear Jason,

Most wine coolers come with some sort of ultraviolet (UV) light protection on their glass doors. Even if it looks clear to you, it might still be blocking harmful UV rays. Keep in mind that UV light is that electromagnetic radiation that comes from things like the sun, tanning lamps and black lights. UV rays can harm a person’s skin, eyes, as well as degrade polymers and dyes, and can certainly have a negative effect on a bottle of wine.

When you start looking for protective films to put over cellar glass, you might come across the term VLT (Visible Light Transmission). The percentage of VLT refers to the amount of light that is allowed to pass through. A film with 10 percent VLT will block 90 percent of the light, only allowing 10 percent to come through. The lower the number, the more concentrated the tint.

VLT and UV measure two different things--even though there’s an obvious relationship between visual light and ultraviolet light. But UV-blocking technology can be more specific, with particular coatings and molecules that can absorb light waves before they become damaging.

This was a really long way of saying that I think that your move to further increase the light protection of your wine is a terrific idea. There’s no one formula of how much light over how much time equates to a particular amount of damage (or not). But any additional light protection might help, and it certainly won’t hurt.

—Dr. Vinny

Collecting Storage Cellars Ask Dr. Vinny

More In Dr. Vinny

How does Wine Spectator review canned wines in blind tastings?

Wine Spectator's expert Dr. Vinny explains the procedure for blind-tasting wines from …

Aug 3, 2020

When will wine from Virginia get the recognition it deserves?

Wine Spectator's expert Dr. Vinny explains why Virginia's wines aren't more well-known on …

Jul 31, 2020

Why do Champagne bubbles come from the bottom of my glass?

Wine Spectator's expert Dr. Vinny explains carbon dioxide "nucleation sites."

Jul 29, 2020

What's the best way to keep a bottle of wine chilled while traveling?

Wine Spectator's expert Dr. Vinny offers tips for keeping your wine cool once it's left the …

Jul 27, 2020

Can I make wine from raisins?

Wine Spectator's expert Dr. Vinny explains why dried-out grapes can make for some pretty …

Jul 24, 2020

Why are red wine grapes fermented with the grape skins but white wine grapes aren’t?

Wine Spectator's expert Dr. Vinny explains why white wines aren't made with grape skin …

Jul 22, 2020