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Originally Posted by kbgl /forum/post/15593474
I agree. IMHO there is really no advantage to adding metallics to a screen paint that contains black pigment. (Simple gray screen.) In a gray mix, black pigment is added for the purpose of reducing both on and off axis gain. Adding metallic or pearl reflective material to the mix to increase the gain doesn't really make sense, unless the intent is to increase on axis gain, while keeping the off axis gain low, which has some advantages. If a more uniform gain is the goal, then it would be easier, and more effective I think, to use less black pigment in the mix.
Well stated, and indicative of the direction I've always taken. In most every case, a Gray Hue achieved via the use of primary colors and the slight addition of "black" that exists within the composition of any Silver always will retain more of a reflectivity quotient than a Gray derived from simply adding Lamp Black to a White base. The avoidance of the "Blue Push" that results as well is to be noted. How one gets to the point of 'balance' is paramount to how well that balance performs. Simply being "Neutral" does not bring the assurance of the most desirable results.
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I have no experience with complex mixes, but here's what I'm speculating.
If lots of highly reflective particles are suspended in a translucent mix, then the diffusion may still be sufficient to avoid hot spotting. I think the reflective particles must be spread out a little from each other for this to work. I also believe that if the particles are flat flakes, then their orientation needs to be pretty random. If the mix is very translucent, (lots of clear material like poly) then multiple coats will be needed so that reflective particles are spread out front to back as well. ( Hey. What if a coat of just poly was used every other coat to put some extra distance between particles front to back?) So if after making sure all this works out, hopefully the gain is a good ways above one, and the screen will be brighter than a simple white screen.
The effect would be a severe muting of the underlying layers, and the Top layer being the only real influence of import. Yet it's performance would be affected in the negative sense by those underlying layers, who would do more absorbing and diffraction of light that reflecting. One cannot apply what is to be considered a even coating of Clear Poly in one application, and once such is applied, it's nor going to be as thin as it would be to allow subsequent additional layers. And how many layers are going to be needed? 3? It doesn't take much distance between particles to create wildly varying results. That's born out by the trials and tribulations of those who have tred experimenting with higher ratios of Poly....and different reflective values (Matte-Satin-Semi/Gloss). It's best described as a "Crap Shoot", with the shooting ground littered with more Crap than anything else.
The singular most defining exception is the DIY S-I-L-V-E-R application, because it consists of a clear matte Poly Glaze with a mere 5% Silver Metallic to the overall mix volume, but must be applied in several (7-8) EXTREMELY light dusting coats. The coatings are very sparse....so much so that the first 2-3 don't even appear to "be there", yet at '5-6' coats something is seen to be happening, and at 8 coats, suddenly you have a "Whitish Silver" surface. But I can state from experience that the end result is still an exceedingly thin paint application, and the reflective Mica particles are evenly spaced, yet arrayed in every possible orientation. This come's from the "Dusting" technique of Spray painting with a HVLP Gun at the proper distance-speed-paint viscosity
Still, it's not unusual for someone "guessing at it" to come up with a surprising result based on their own needs and criteria. I've seen those with anemic PJs use Silver Behr Screen in Eggshell produce excellent results across the board, and someone else try the same thing with a different PJ and get dismal colors or Hot Spotting. The same can be said with a simple Gray. Being "Neutral" merely helps eliminate undue color pushes. Different PJ capabilities and Room conditions can both work to offset or compound issues.
Far harder it is to come up with something that works across a broader base of PJ choices and viewing conditions. THAT was, and remains my primary interest and focus as to performance and visual quality.
Fact is, if the distance between successively applied layers of a paint that itself contains a translucent base w/everything that is within it in also being "in balance" and at the "CORRECT" distance/spacing, the screen will perform optimally.
But of course, that would depend upon the mix, wouldn't it?
Using the type of mixes that use a loose suspension
(within a Water/Poly Base) of primary colors AND reflective partials (...with the latter also introducing Black to the point of effecting a complex "Graying" as well...) allows light to react individually with ALL the components. Then as a blending of all those reactions occur at the point of surface reflection, a reflection of higher efficiency and intensity results.
Point of Note:
Macros of Silver Fire show a veritable blending of Red-Green- Blue-Black/Silver components. Step back and it's plainly "Gray" in color. Although this almost "prismatic" effect can only be seen when D65 white light is shown on the surface and at a 400%+ macro level, it was touted as a reason by some "Neutral Gray via Aluminum" proponents that achieving Gray by such a "Blending" was adverse in nature.
But it was/is not. It simply represents a proper distancing and separation of the components of "Color" that allows light of varying wavelengths to be slightly more amplified that would be the case if those same components were more tightly spaced.
And "Spaced" is the right wording. Tints do not "meld" when mixed....they are in fact simply "mixed'. Without the "separation" that mixing within a Poly/Water base provides, everything will be much more densely "packed".
All the way down to the
"Molecular Level"
That "Truth" has seemed lost on many, and has resulted in much adversity and contrary opinions.
And.....for some, the need/desire to distance themselves from that particular "mantra" has actually led to some new and interesting routes....that coincidentally seem to lead back to the same starting point.
Black Widow comes about it's various levels of "Grayness" by the blending of the extreme tendency of Aluminum to introduce "Black" within a "Yellow Tint" based paint...which of course came into being by the blending of other separate color components. A neat trick...and one I've always admired....and still do. But from out of it's conception also came the realization that there was a looming wall of reflectivity vs "Grayness". Enough Aluminum to be very reflective also produces too dark a Gray. Alteration of the Color base and reduction of the amount of Aluminum is the only path left for Black Widow to take from it's darker beginnings. As I said....it all can depend upon what route you take get there.
Stumble off the path through a Rose Garden and even a seemingly beautiful Rose can draw blood. (...I made that up...
)
The above statements do not allude to being a declaration of worthiness or dispute of the "theory" behind either approaches. Simply put....they are two distinctly different approaches to the same goal
So what's the "Why not use Gray only" quandry?
Complex Grays that are created by a more "dense" blending of components can have the advantage of being made more "Neutral", but also cannot be as reflective as a "Complex Gray" that achieves "Neutrality" via a "balance" within a looser, translucent suspension. The last post speaks of How can?" or "What if?" , but the answer is already well known.
Higher Lumen PJs can allow a simple Neutral Gray screen to look fantabulous...of that there is no doubt. But most always on "Normal Bulb" settings...not on "Econo", which is where most PJ Mfg designs prefer to operate to achieve the best contrast and longer Bulb life.
Example: A Epson 6500's 70,000:1 Contrast can only be obtained by use of "Low lamp" mode....and a "Theater" setting that engages the Auto Iris. Without either or both so employed.....6000:1 tops. And the Lumen output of the PJ drops by 65%. That's simply necessary....for too much light output destroys the Auto Iris's ability to do it's job. PJ's whose native contrast are at/over 15000:1 on "Normal Lamp" have simply found a way to reduce/eliminate light leakage onto the LCD panels / DLP Chip-s. That being so, they can actually have lower Lumen specs yet deliver a sharper, more vibrant image. And if the right PJ is matched with the right Screen surface.....all bets are off as far as "accepted performance".
Introduce the 6500's Low lamp-Iris assisted projected image onto "A Gray Surface w/a balanced and equal dispersion of Reflective Particles and the far lower lumen output will still produce enough illumination that the screen will use it in a optimal fashion. That means the screen surface absolutely MUST be of a gain of 1.0 to 1.3
.85 won't be the same...not even .95...you can believe it.
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For someone wanting a really large screen, or with a low lumen projector, or both, this may be the ticket. But for someone with a high lumen projector, or smaller screen, the simple gray screen with a gain of one or lower may be more suitable.
Again well stated....but something a bit too broad reaching. In any case where a PJ can operate at Lower Lumen setting yet retain "PoP" on screen, Black Levels will be superior to those of a simple Gray. And any reflective Screen application that cannot show a Gain of 1.0 cannot allude to being of any real advantage over the simple 'Gray Screen' except as to if it either directs all it's light straight backwards, or scatters it evenly in ALL directions.
You just never will have any such advantages come from a simple gray screen, because all the latter can ever be is a "light Attenuating" surface, and that attenuation increases from the center of the image outward. That applies to the Complex Screens as well, but to such a lessor extent it is not discernible as being an issue....except with Retro-Reflective applications.
To wit, and to close;
A screen is a reflection of what it receives, so why would one want to use it simply to lessen the "reflective" experience. Nay...it should augment the experience when needed and necessary, yet never detract from the experience when not.
