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Odd Little Things · entry 8 of 52
Modern mirrors are usually glass with a thin reflective metal coating applied to the back surface.
The longer version
Glass alone is transparent and nearly useless as a mirror. What reflects is a very thin film of metal laid on the rear face, so light passes through the glass, bounces off the film, and passes back out toward you. A coat of paint over the film protects it, since the metal layer is far thinner than a human hair.
Silvering with silver was standard for a long time before cheaper chemical deposition of other metals took over. Putting the film at the back rather than the front protects it from scratches and tarnish, at the cost of a faint second reflection from the front surface, visible as a doubled ghost image when you look into a mirror at an angle.
Where this entry sits
Odd Little Things looks at the ordinary objects people touch every day and the small mechanisms and histories hiding inside them. Buttons, zips, pencils, mirrors, stairs, stamps, packaging, and road signs all get their turn. The full list sits on the Odd Little Things page, where every entry is listed in order.
More From Odd Little Things
Eight more entriesA mirror reverses left and right only because you imagine yourself stepping behind its surface.
Read 10Polished metal served as the earliest mirror long before glass mirrors became widespread.
Read 11Stairs are built with a rise and a run that together determine how steep the climb feels.
Read 12Handrails exist largely to give the hand something stable to hold while balance is shifting.
Read 13A door handle works as a lever that pulls a latch back so the door can swing open.
Read 14Round doorknobs became common partly because a smooth shape is easy to grip and turn.
Read 15Coins often have milled edges, a ridged pattern originally meant to reveal clipped metal.
Read 16Reeded edges on coins also make stacks easier to handle and harder to counterfeit crudely.
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