Dating old mirrors black paint backside

Just because a mirror looks like an antique doesn't necessarily make it so. Reproduction mirrors may have the same shape or style as their true antique counterparts, or a new mirror may be housed in an old frame. Telltale signs of age, such as oxidation and scratches, help determine whether that prized mirror is a reproduction or true antique.

The glass is often an indicator of a mirror's age. Modern sheet glass is typically smooth and free of bubbling, thanks to manufacturing techniques that weren't known in centuries past. Look closely at the mirror glass for a slight waviness or random bubbles within the glass. Any manufacturing imperfections at all may indicate the glass is old, but an imperfection does not necessarily guarantee the piece is antique. If the mirror glass looks perfect and pristine in every way, including the mirroring itself, there's a good chance the piece is not old.

The reflective coating used on the back of the glass is what makes a sheet of glass become a mirror. The materials used to create this effect have changed greatly over the years. Beginning in the 16th century, mercury was spread over a thin layer of tin. Glass was placed atop the mercury, and a reaction between mercury and tin caused the mirror-like substance to adhere to the glass. Old mercury mirrors age to create a somewhat sparkly effect. If the mirror has a sparkly, crystalline appearance behind the glass, it likely is an antique.

The mirror-like coating on the back of an antique mirror, whether made with tin and mercury or a thin sheet of silver, tarnishes or oxidizes over time. This results in dark or blotchy spots visible through the glass when looking at the front of the mirror. If you've ever looked at an antique mirror you know to be antique, you may have recognized this effect when seeing your reflection. On a true antique mirror in a frame, the oxidation is probably greatest near the bottom, as moisture from cleaning the mirror seeps down behind the frame and may soak the mirror backing at times. If the oxidation looks too even or uniform, the piece may not be antique. Look for scratches that seem they've been there for a long time as well, as they may indicate a true antique. These same qualities also apply to hand mirrors.

Carefully studying the frame also helps determine whether the mirror as a whole is new or old. Look for signs of wear, such as chipped or worn details on a carved frame. Check the back of the mirror to see how it's attached to the frame; if you see modern Phillips-head screws, this indicates either the mirror is fairly new, or the screws have been replaced. Although not entirely common, seek a maker's tag or mark on the back of the mirror or frame, as this helps pinpoint the mirror's age. If the frame itself looks brand new, as if it has no dust or discoloration in any of the details, there's a chance it is not an antique.

Kathy Adams is an award-winning journalist and freelance writer who traveled the world handling numerous duties for music artists. She writes travel and budgeting tips and destination guides for USA Today, Travelocity and ForRent, among others. She enjoys exploring foreign locales and hiking off the beaten path stateside, snapping pics of wildlife and nature instead of selfies.