Spandex DIY AT Screen Fabrics and Properties

Here is a Spectral Reflectance Chart of a combination of White Matte Milliskin Spandex over Light Silver (which, at ~N6, is actually a dark gray) Matte Milliskin that is being recommend for screen use on another forum. As can easily be seen by comparing this chart with the charts for the individual Spandex material charts, in the first post of this thread, light is being reflected from the Light Silver layer and illuminating the back of the White layer then continuing through the white layer to reach the spectrophotometers sensor (or the human eye in the case of screen use). This does two measurable things, first it produces a screen color that is a combination of the reflective qualities of the two fabrics and second it brightens the image a bit. The problem with this is the two fabrics each have unusual spectral curves that when added together (which is what you see in this chart) combine the color problems of each fabric rather than cancel them out. The white fabric has a steep boost in the deep blue section of the spectrum while the light silver has a steep boost in the red area. It is in question whether both can be compensated for at the same time through projector calibration, and the overiding question is why use the silver fabric as a secondary layer in the first place. The answer is YOU SHOULDN'T! The best Audio Transparent screen will result from using a single layer of the white fabric alone. The main problem with this is that almost any source of light (power lights from any equipment or any light reflected from objects) behind the screen will show through the screen material and appear as part of the image. A similar problem would occur if the wall in back of the screen was painted a light color. The obvious answer is to use a black second layer to absorb as much light as possible that makes it's way through the first layer or tries to come thought from behind the screen. This is why many commercial screens have a black rear layer of material as well. The only layer of the screen that we want reflecting light back to the viewer is the top of the first layer. This is true whether using a fabric or a painted screen.

So what does happen with a white/silver dual layer Spandex screen? It's simple physics folks; the light that passes through the white layer will be diffused like light that passes through a translucent white milk jug and will blur the image. That light will then strike the silver layer and some of it will be reflected back toward and through the white layer TO COMPETE WITH, NOT JOIN, with the light reflecting from the surface of the white layer. The result MUST be a softening of the projected image. The other thing that happens is that the light from the silver layer will brighten the perceived image a bit, but such brightening from a diffuse source MUST in fact LESSEN the contrast of the image not increase it as some misguided people suggest.

It's really amazing to read how those advocating a white/gray dual layer Spandex screen suggest how such a screen works. Their theories don't work when using a mirror as a background and they fail even more so by using a diffusive fabric as a rear reflective layer. Painted and fabric screens do not and can not work this way. You will notice that anyone saying they can will offer no objective proof of performance and, at best, try to prove their theories by showing screen photos that in fact prove nothing, one can't even tell from a "screenie" (a photo of a screen being used) if the screen in question is white or gray! The physics of light (refractive and reflective) are well known and have been proven over and over again as the scientific method demands. Those that ignore them base their theories on hot air and wishful thinking.