# Silver mirrors? Illusion? **URL:** \ **Category:** Factual Questions\ **Created:** [March 18, 2002, 7:03am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846 "2002-03-18T07:03:49Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![warmgun](https://avatars.discourse-cdn.com/v4/letter/w/ecccb3/32.png) [@warmgun](https://boards.straightdope.com/u/warmgun)\ **Post date:** [March 18, 2002, 7:03am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/1 "2002-03-18T07:03:49Z")
I was in a glass store the other day and noticed the display mirrors. They had regular (silver), gold, bronze, blue(?) along with several others. But I got to thinking…the silver one wasn’t really silver, merely a reflection of what it’s reflecting. You really can’t even see a ‘silver’ mirror. So I started asking my friends what color a mirror was, without exception they all said silver. I checked the Crayon box they’re definately not ‘silver’. So why do we perseve them as such? ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 18, 2002, 7:32am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/2 "2002-03-18T07:32:11Z")
Pure silver has a high reflectivity througout the visible wavelengths. Consequently, we refer to this quality as “silver.” ---
**Author:** ![Shayna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/shayna/32/17976_2.png) [@Shayna](https://boards.straightdope.com/u/Shayna)\ **Post date:** [March 18, 2002, 9:53am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/3 "2002-03-18T09:53:01Z")
Not that there were any difinitive answers in it, but here is a previous thread on this topic: [why do we think of mirrors as silver?](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=9457) And although it’s on a different subject, **Uncle Cecil** has this to say about mirrors and silver: > [@](#): > > [http://www.straightdope.com/classics/a4\_015b.html](http://www.straightdope.com/classics/a4_015b.html) > > (bolding mine) > > The trick is that the two reflecting surfaces are the front and back of the same piece of glass. Said glass is specially ground so that the back surface is slightly tilted relative to the front one. In other words, the glass looks wedge-shaped from the side. **The back surface is coated with silver like a bathroom mirror, making it highly reflective**. The front surface isn’t coated, but it’s still slightly reflective, like all glass. So it appears we think of mirrors as silver because they’re coated with silver. Seems pretty logical, no? ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [March 18, 2002, 6:19pm UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/4 "2002-03-18T18:19:15Z")
It also has to do with the nature of color. The “metallic” colors – silver, gold, copper – have to some degree an element of reflectance to it. Drop the reflecting ability, and silver is just another shade of gray; color wheels don’t include it. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [March 18, 2002, 6:57pm UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/5 "2002-03-18T18:57:17Z")
Just a note since this is the SD site. Most “silvering” for mirrors these days is aluminum which is deposited on the surface in a vacuum by vaporizing the aluminum. Aluminum is as relective as silver (Encyclopaedia Britannica) and doesn’t tarnish like silver does. ---
**Author:** ![bbeaty](https://avatars.discourse-cdn.com/v4/letter/b/c0e974/32.png) [@bbeaty](https://boards.straightdope.com/u/bbeaty)\ **Post date:** [March 18, 2002, 9:06pm UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/6 "2002-03-18T21:06:35Z")
> [@](#): > > \*Originally posted by warmgun \* > \*\*I checked the Crayon box they’re definately not ‘silver’. So why do we perseve them as such? \*\* But crayons are full of powdered aluminum! Use sandpaper on an aluminum mirror, and it will look like silver paint. Weirdness: mirrors are the color of electricity! At one time “quantity of electricity” meant “quantity of charge” rather than the term “quantity of energy” used by electric companies. Metals are full of mobile charges. Metals are extremely reflective because their conductivity “shorts out” the e-field component of incoming light waves. The word “conductor” essentially means “container of mobile electricity-stuff.” So… during electric currents, it is the silvery part of a metal which does the flowing. And when you look at a mirror, you are looking right into a flat slab of “liquid electricity” trapped within the metal. Or we could just say that mirrors are “metallic colored.” So, did you know that the color “white” is usually made of powder where the individual particles are little transparent prisms? ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [March 18, 2002, 10:32pm UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/7 "2002-03-18T22:32:28Z")
> [@](#): > > \*Originally posted by bbeaty \* > \*\* > > Metals are extremely reflective because their conductivity “shorts out” the e-field component of incoming light waves. I’m sure you know this but _“shorts out” the e-field component of incoming light waves_ is a fairly unique way of putting it. The more common description is that the mobile charges in the conductor set up an opposing E field that cancels the incident E field. An interesting aspect of this is that the incident E field cannot instantly cancel so what is called an evanescent wave continues into the conductor for some distance (skin effect). Similarly, if light propagating in glass is incident on a glass/air interface at the critical angle it is 100% reflected. But if another piece of glass is brought very close the evanescent wave will, in effect, jump the barrier. This is remarkably similar to quantum mechanical tunneling. ---
**Author:** ![warmgun](https://avatars.discourse-cdn.com/v4/letter/w/ecccb3/32.png) [@warmgun](https://boards.straightdope.com/u/warmgun)\ **Post date:** [March 19, 2002, 5:22am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/8 "2002-03-19T05:22:03Z")
Thanks all. Still seems confusing. > [@](#): > > \*Originally posted by Shayna \* > \*\* So it appears we think of mirrors as silver because they’re coated with silver. Seems pretty logical, no? \*\* I wouldn’t think the ‘man on the street’ would use this logic. They look silver to me as well. But unlike a bronze mirror, you really see no color at all except those reflected. ---
**Author:** ![istara](https://avatars.discourse-cdn.com/v4/letter/i/e79b87/32.png) [@istara](https://boards.straightdope.com/u/istara)\ **Post date:** [March 19, 2002, 7:56am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/9 "2002-03-19T07:56:03Z")
Silver is a grey-white metal, so the reflection you get in a silver mirror is slightly duller-grey than real life. It’s also not perfectly reflective - it will absorb some of the light, so it’s duller. IIRC my science teacher said that other metals theoretically make much better mirrors as they’re “whiter”, however cost or practicality rule them out. I seem to remember he gave calcium or some such other reactive element as a good example. But the problem with it is that it decays pretty instantly in oxygen, so would dull immediately. If you sliced through it very straight, for the nano-second or whatever before it oxidised, it would be an excellent mirror. Personally I quite like those mirrors with tinted glass that make you look more tanned and golden that you really are (if you’re white and pasty-pale like me…) ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 19, 2002, 8:42am UTC](https://boards.straightdope.com/t/silver-mirrors-illusion/98846/10 "2002-03-19T08:42:03Z")
> [@](#): > > \*Originally posted by istara \* > **IIRC my science teacher said that other metals theoretically make much better mirrors as they’re “whiter”, however cost or practicality rule them out.** That might be true (I’m not sure) but of little practical importance. If you want a mirror better than silver, you simply use multilayer coatings. You apply coatings with thicknesses which are 1/2 the wavelength of light so the reflection from one layer interferes constructively (reinforce each other) with the reflection from another layer. You can get much better than 99% reflectivity. The same principle is used for anti-reflection coatings on lenses, except the thicknesses are 1/4 wavelength so the reflections interfere destructively (cancel each other out).