question: Why do images "drawn" on fogged up mirrors show up again the next time the glass is steamed up?
comment: Grease! The grease on your fingers makes it harder for water vapor to condense on the mirror in the spot where you touched it. Try drawing images with a dry cloth or something and see the difference.
passages: The formation of mist, as of other suspensions, is greatly aided by the presence of nucleation sites on which the suspended water phase can congeal. Thus even such unusual sources as small particulates from volcanic eruptions, releases of strongly polar gases, and even the magnetospheric ions associated with polar lights can in right conditions trigger the formation of mist and can make mirrors appear foggy. Mist on mirrors should not be mistaken for condensation as they are very different. Mist is a collection of water droplets but condensation is the water droplets in a different form. 
   Silver stain is a common problem in roller transporter processors, since the material (usually paper) is pinched between squeegee rollers to remove excess developer and brought into the fixing bath without intermediate rinse or stop. Developers for such applications usually contain an antistaining agent, usually soluble organic thiols that form soluble but non-reactive silver compounds with free silver ions.
  
  With modern emulsion technology and well formulated developers, silver stain has become uncommon.
  
  Section::::Chemical fogging.:Intentional fogging.
   Light fogging on a print usually only occurs because of poor control of lighting in the darkroom and is seen as an overall dark veil across the print or, occasionally, as unintended solarisation.
  
  Section::::Chemical fogging.
  
  Section::::Chemical fogging.:Unintentional fogging.
   “You know, that rays of light reflected from different bodies form pictures, paint the image reflected on all polished surfaces, for example, on the retina of the eye, on water, and on glass...coat a piece of canvas with this matter, and place it in front of the object to be taken. The first effect of this cloth is similar to that of a mirror, but by means of its viscous nature the prepared canvas...retains a facsimile of the image...The canvas is then removed and deposited in a dark place. An hour later the impression is dry, and you have a picture”
   The formtion behavior of condensation on the mirror's surface can be registered by either optical or visual means. In both cases, a light source is directed onto the mirror and changes in the reflection of this light due to the formation of condensation can be detected by a sensor or the human eye, respectively. The exact point at which condensation begins to occur is not discernible to the unaided eye, so modern manually operated instruments use a microscope to enhance the accuracy of measurements taken using this method.
   The issue of the photoswitch that the reflecting efficiency of the reflecting member may be drastically lowered due to dewing and clouding of the reflecting surface due to a change in the ambient temperature. The dew on the reflecting surface causes a random reflection. In order to avoid the clouding of the reflecting surface, it has been proposed to apply silicon or the like to the surface of the reflecting member. This countermeasure, however, cannot prevent condensing of dew onto the lower part of the reflecting surface. Thus, there are many problems in the prior art.
   A protective overcoat is usually applied before the mirror is removed from the vacuum, because the coating otherwise begins to corrode as soon as it is exposed to oxygen and humidity in the air. "Front silvered" mirrors have to be resurfaced occasionally to keep their quality. There are optical mirrors such as mangin mirrors that are "second surface mirrors" (reflective coating on the rear surface) as part of their optical designs, usually to correct optical aberrations.
   They are made for applications requiring a strict reflection without a "ghosting" effect as seen with a second surface mirror, where a faint secondary reflection could be observed, coming from the front surface of the glass. This includes most optics applications where light is being manipulated in a specific manner. Telescopes, rear-projection televisions, periscopes, non-reversing mirrors, high quality kaleidoscopes, and the animation process Spectrafocus use this type of mirror.
  
  Section::::Silvering.
  
  The "silvering" on a front surface mirror is usually aluminium for visible light and gold for infrared radiation.
   In the 1966 book "Les Mots et Les Choses" ("The Order of Things"), philosopher Michel Foucault devotes the opening chapter to a detailed analysis of "Las Meninas". He describes the ways in which the painting problematizes issues of representation through its use of mirrors, screens, and the subsequent oscillations that occur between the image's interior, surface, and exterior. In his book, "The Dying Animal", Philip Roth uses "Las Meninas" as a metaphor for the distracted attraction of courtship.
  
  Section::::Return to Spain and later career.:Final years.
   An aluminium glass mirror is made of a float glass manufactured using vacuum coating, i.e. aluminium powder is evaporated (or "sputtered") onto the exposed surface of the glass in a vacuum chamber and then coated with two or more layers of waterproof protective paint. 
   Infrared thermography, thermal imaging, and thermal video, are examples of infrared imaging science. Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation, called "thermograms".
   Section::::Description.
   Fogging (photography)
  
  Fogging in photography is the deterioration in the quality of the image caused either by extraneous light or the effects of a processing chemical.
  
  Section::::Taxonomy of fogging.
  
  One kind of fog is produced from a silver halide crystal having a fog centre created by various reactions. One obvious case is when the emulsion is inadvertently exposed to light. In this case, the fog centre is created as latent image and made into visible fog by the action of the developer. Another case is when the fog centre is created chemically, with propylene glycol and white wax.
   Reflection Haze is an optical phenomenon usually associated with high gloss surfaces, it is a common surface problem that can affect appearance quality. The reflection from an ideal high gloss surface should be clear and radiant, however due to scattering at imperfections in the surface caused by microscopic structures or textures (≈ 0.01mm wavelength) the reflection can appear milky or hazy reducing the quality of its overall visual appearance.
  
  Causes of this could be due to a number of factors –
  
  BULLET::::- Poor dispersion
  
  BULLET::::- Method of applying the coating
  
  BULLET::::- Variations in drying, curing or baking
   In "Traces (Light and Weight)", the sounds of a match being struck and water droplets, symbolising the elements of fire and water respectively, form a loop together with a light beat, and the chiming of church bells entering occasionally. A vague crying sound and the chiming continues and after the beat stops, it fades into the following song.
   The Pepper's ghost technique, being the easiest to implement of these methods, is most prevalent in 3D displays that claim to be (or are referred to as) "holographic". While the original illusion, used in theater, involved actual physical objects and persons, located offstage, modern variants replace the source object with a digital screen, which displays imagery generated with 3D computer graphics to provide the necessary depth cues. The reflection, which seems to float mid-air, is still flat, however, thus less realistic than if an actual 3D object was being reflected.
   The glass is sensitive to light that when passes through a mask can ultimately turn it into a permanent picture with a heat process "fixing" permanently the image. Silver glass "latent images" will develop in 3–4 hours at 886–976 °F.
  
  Gold glass "latent images" require a higher temperature of 968–1058 °F and over a similar period of time for postbaking. Postbaking hastens the occurrence of the particles with the shadow areas of the negative, permitting deeper penetration into the glass than the highlighted areas. This gives the picture three dimensions and color.
   The algorithm considers two main processes: "Reflection" and "Visibility". Reflection process simulates the light reflection mechanism, while visibility simulates the visibility of matching patterns. These two processes are used as a search strategy to find the global optimal solution. The formulation of finding the new solution ("newP") by using "reflection" and "visibility" is as follows:
  
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   Section::::Modern adaptations.:Other.:"Mirror Mirror".
   Again, the man thinks he hears someone and goes to the door. This time we get to see down the corridor; predictably it is empty, grey and ends in darkness. When he goes to the window we get to see outside this time; it is night, rain is falling in the dim light. The camera returns to the pallet and to the mirror which is a small grey rectangle, the same dimensions as the cassette. There is nothing reflected in the mirror at first. When the camera returns we see the man in it. He closes his eyes, opens them and then bows his head. Each of the inspections is interspersed with a God-like view from above.
   BULLET::::- The short story "Tlön, Uqbar, Orbis Tertius" by Jorge Luis Borges begins with the phrase "I owe the discovery of Uqbar to the conjunction of a mirror and an encyclopedia" and contains other references to mirrors.
  
  BULLET::::- "The Trap", a short story by H.P. Lovecraft and Henry S. Whitehead, centers around a mirror. "It was on a certain Thursday morning in December that the whole thing began with that unaccountable motion I thought I saw in my antique Copenhagen mirror. Something, it seemed to me, stirred—something reflected in the glass, though I was alone in my quarters."
   Snyder proposes it is "a mirror of majesty" or an allusion to the mirror for princes. While it is a literal reflection of the king and queen, Snyder writes "it is the image of exemplary monarchs, a reflection of ideal character" Later he focuses his attention on the princess, writing that Velázquez's portrait is "the painted equivalent of a manual for the education of the princess—a mirror of the princess". 
   Defined as the gloss at grazing angles of incidence and viewing
  
  BULLET::::- Contrast gloss – the perceived brightness of specularly and diffusely reflecting areas
  
  Defined as the ratio of the specularly reflected light to that diffusely reflected normal to the surface;
  
  BULLET::::- Absence of bloom – the perceived cloudiness in reflections near the specular direction
  
  Defined as a measure of the absence of haze or a milky appearance adjacent to the specularly reflected light: haze is the inverse of absence-of-bloom
  
  BULLET::::- Distinctness of image gloss – identified by the distinctness of images reflected in surfaces
   By controlling the thickness and density of metal coatings, it is possible to decrease the reflectivity and increase the transmission of the surface, resulting in a "half-silvered mirror". These are sometimes used as "one-way mirrors".
   Still Life with Mirror
  
  Still Life with Mirror is a lithograph by the Dutch artist M. C. Escher which was created in 1934. The reflection of the mirror mingles together two completely unrelated spaces and introduces the outside world of the small town narrow street in Abruzzi, Villalago, into internal world of the bedroom. This work of Escher is closely related to his later application of mirror effect in 1937 Still Life and Street. Escher manipulates the scale in different parts of the print to achieve the effect of smooth connection between worlds.
  