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Discussion Starter · #1 ·
I realize from another thread that you cannot just add AAA to grey paint as it will do a blue push, but my question is


What is the function of AAA, or Pearlesence,Goldflex, Polycrilic in the paint mix?


I realize the grey is there to sharpen the blacks, when your doing just a N8 screen. Is the addition of those other ingrediants there to boost the whites?
 

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Ramble Warning!


The purpose of adding any form of reflective particle is to increase the on axis reflectance. Using particles that are not all laying flat also introduces some dispersion of the light. The term "optical texture" has been used to describe this.


In the case of the Auto-Air Aluminum Base Fine it adds aluminum reflective flakes. The medium that the flakes are carried in also adds some surface sheen. There may also be some pigment such as Lamp Black, but I'm not sure if that has been determined conclusively yet. The medium is also quite thin like a polyurethane so the addition of the AAA improves the ability of the paint to level out to a smooth surface with minimal roller texture.


The craft metallic and pearl paints have mica flakes in them. Some of these are clear and some are silver. The mica flakes can have other material deposited on them. Some of them seem to have a silvery coating deposited on them. A typical silver metallic craft paint like Delta Silver Metallic is simply a semi-clear base with pigment in it to make it gray and some clear mica flakes. These same flakes are used in the Delta White Pearl but the base has some white pigment.


The quality, size, concentration, and behavior of the mica flakes in the craft paints varies widely. In many cases the mica flakes are iridescent and change their prominently reflected color with angle. This has been shown to lead to some unwanted color shifts when used in a clear coat.


The silver metallic paints that use a silver coated mica flake should not cause unwanted color shifting. In Harpmaker's Cream & Sugar mix the Michael's house brand of silver metallic is used. When mixed with Sherwin Williams Luminous White (IIRC) the results is a very light N9 neutral gray. I am speculating that the flakes are silver coated and not clear and that is why no color shifting or iridescent behavior has been observed with C&S.


The addition of water base polyurethane to advanced mixes was meant to make the paint more translucent. This was to allow more light to interact with the mica flakes in the mix. It has been suggested that the BW developers should investigate this as a way to allow more of the aluminum flakes to interact with the light but I don't know if any experimenting has been done.


Adding a satin polyurethane like Minwax Clear Satin Polycrylic to any paint will do two desirable things. It will thin the paint and enhance it's leveling ability. With the new higher resolution projectors a smoother surface is beneficial to get the most out of those extra pixels without introducing graininess. The satin polyurethane also adds some surface sheen and to a lesser degree translucence. This will narrow the the viewing cone and boost the on axis gain. Since this increased reflectance is continuous across the surface there are no visible particles and no resulting graininess to the image. Adding the satin polyurethane in proportion high enough to match the on axis gain boost of the aluminum flakes in Black Widow does not seem to cause hot spotting but on occasion it has been reported to cause a "wet look" to the image. I have not observed this "wet look" but I speculate it would be similar to the look of a glossy photo. However the graininess introduce by all forms of visible reflective particles is not an issue.


So there is a trade off between the higher gain boost of AAA that has a very subtle graininess to it or the more transparent characteristic of a satin poly enhanced neutral gray that very occasionally has "wet look" to it.


With the much brighter home theater projectors that have been available in the last year or so, that most people would be well served by a select OTS neutral gray. If one wants to maximize the ambient light performance then the Black Widow would be the best choice. If you want to have total control over the shade and on axis gain boost then the OTS Neutral Gray and Satin Polyurethane is a good option.


I personally feel that the shimmering introduced by some of the craft paint pearl and silver metallic mixes is unacceptable. That is why I abandoned all the work I had done with the use of pearl mixes and clear coats.


It was also shown that matte polyurethane top coats caused a filtering effect that resuled in a noticeable red-orange color shift. In addition to that I found that the Behr Matte Polyurethane does not remain matte. If it is wiped down with a damp clothe it will have a higher sheen and hot spotting will result. In fact I believe that it was on the verge of hot spotting right off the bat.


IMHO, the best way to approach front projection in a moderate to high ambient light situation, is to start with a bright projector. Try various shades of neutral gray until you feel the blacks are adequate and the whites are not quite adequate. Then try various top coat mixes utilizing the neutral gray paint shade with varying amounts of Minwax Satin Polycrylic. I would start at the high end of Polycrylic content that would be a mix 3:1 flat paint to satin polycrylic. If you are happy and there is no hot spotting you are done. If there is hot spotting or excessive "wet look" then try a 4:1 mix, then a 5:1 mix etc.


When looking for a projector for use in this sort of environment don't limit yourself to home theater projectors. There are getting to be more wide screen presentation projectors available with much greater brightness and respectable CR. There are also home theater projectors such as the Panasonic PT-AX200U that were specifically designed for use in a typical living room situation with higher ambient light conditions.


Just remember there is no "Best" anything in this game. There is only the optimum combination of projector and screen for any given environment.


Sorry for the rambling.
Sometimes I think out loud and sometimes my thoughts just pour into the keyboard.



I hope the answer to your question was in there somewhere.
 

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It makes the screen more directional, which helps the screen appear to be a little darker in ambient light, but brighter when light is projected onto it.
 

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Discussion Starter · #4 ·
Thanks for the info,


I have been experimenting and did 2 test panels last night after I bought a new bulb..


BW mix with 25% Behr Ultra White 4850 base, and a second test with BW+25%white + 25% AAA.


I noticed compared to my current BW screen the BW+25%w did improve somewhat whites and only had a slight drop in blacks. Watched some hockey night in Canada for that to be really apparent.


The BW+25%w+25%AAA, REALLY improved whites over standard BW, but vice versa my blacks suffered but it did punch up the other bright colours while dropping the richness of others ie dark reds. The test screen had that silver sheen look of movie screens more so than my base BW screen.


I was thinking what the effects of a darker Grey would have when mixed with say silver pearlesence or silver metalica. For that matter a dark grey mixed with say BW+25%AAA.


That is why I was wondering about the fuction of these additives. If I go darker grey, but add the reflectiveness to help punch up the whites without dropping the blacks if that is even possible.
 

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Cnd Joe

Great question.


Tiddler

Great answer




I kind of predicted a few years back that what I saw was a trend in digital projectors was more lumens available for people with ambient light issues coming in the future. Screens haven't totally caught up IMHO yet. DIY still allows the best choice if one is willing to experiment to completion with projectors and screen colors to best match the environment they are intended to be used in. I have always suggested stopping at the simplest of solutions that maximizes your viewing experience. And in my case that was to find the brightest of projectors thus allowing the simplest of solutions.


I showed in a thread the effect of a gray screen and ambient light taken to the extreme limits where I projected to a coal black screen an image that produced very bright whites. The lumens required were outlandish but to me that experiment clearly explained the function of a gray screen.

That thread can be found linked in my signature below along with other threads with my thoughts on metallic additives and also poly.
 

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Here's a picture of what I'm talking about. Please ignore the color shift and exposures. I hung a piece of 8.5" x 14" white paper on this near white screen and took photos with ambient light and with a flash. The paper appears lighter with ambient light, but darker than the screen with a flash. So a projected image should be a little brighter, and a dark image could be a little darker I think. The pictures I took using projected light were just confusing, and showed nothing. Please consider this as an explanation of my idea, and not proof that the idea is correct.




Note. Photo also reveals uneven paint thickness in the flash shot. My other screen luckily does not have this problem.
 

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I have posted these images a few times before but not in the last year or so. It shows the same thing mentioned above and points out the importance of maximizing surface sheen without going into the range that produce a hot spot. That is different for every combination of projectors and screen size and screen surface.


The two photos shown are of a common test screen one with ambient lighting and the other with cam flash. The flash can be thought of as a type of projector of white light when trying to reason thru this idea. All grays in the test screen were the same paint what varied was the poly added thus the appearance of different shades of gray depending on what the light hitting it did. The quadrant that looks the darkest under ambient lower left looks the whitest under flash. If one to assume when black is projected we are seeing the screen as what the ambient is showing us and when white is projected we see it improved by the sheen then we have a increase in perceived contrast. There is a bit more to it than that but that was my thoughts when I took those photos several years back.


No flash



Flash
 

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I probably got this idea from reading your old posts.
It just took a while to sink in and for the logic to become clear to me.
 

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Quote:
Originally Posted by tiddler /forum/post/15516596

Ramble Warning!


The purpose of adding any form of reflective particle is to increase the on axis reflectance.
Quote:
Originally Posted by kbgl /forum/post/15516627


It makes the screen more directional, which helps the screen appear to be a little darker in ambient light, but brighter when light is projected onto it.

Gentleman,


I cannot concur with those statements.


Literally YEARS of experience and use with metallics in "DIY Screen" paint has shown others and myself that when such reflective elements are properly arrayed within the constitution of a mix, as well as properly applied, the resulting evenness in light dispersion does not...and will not increase "On Axis Gain" to any greater extent that it will "decrease "Off Axis Gain".


I've personally shown this to be a cold, hard, and non refutable fact with countless 179 degree off axis screen shots. In all of those examples, ONLY S-I-L-V-E-R exhibited any such decrease (slight but "observable") in viewing cone


For both of you, your recent forays and subsequent fixation on applications like Black Widow, a mix that uses a specific Aluminum element that has for years been all too well known to introduce both retro-reflectivity AND granularity, is leading you both to make broad, sweeping...even judgmental statements as to "What does what and why".


There is not a single published specification that shows that the aforementioned application is in ANYWAY superior (or even on par with) similar "Mica-Based" DIY Screen paints that utilize a far greater percentage of reflective elements. Just a whole lot of repetitious expounding on how superior it "MUST" be.


It is telling though how the use of such "reflective elements" was finally deemed both correct and advantageous by the same Folks who worked so long and hard to decry the use of such as being detrimental. It does seem obvious that once a decision was made to try to improve upon simple Neutral Gray applications, a bit of a closer, harder look at reflective materials was deemed necessary.


As was the case some 2-3 years back with CGIII, and other similar "Aluminum-Based" concoctions, considerable reflectivity (ie:Gain) was achieved, but ALWAYS of a retro-reflective nature. So obviously, much ado was made along the lines of "Well, if you are not sitting to the side...whats the issue?" Typical retorts when one is combating a simple truth.

"A Screen that is designed to disperse light evenly across the entire surface, and equally in ALL directions out from the surface of the screen, will provide the BEST, MOST BALANCED image."


...........also;

"The introduction of a Gray hue, balanced with the use of a Reflective element, can and does enhance Ambient Light viewing ability beyond that of a neutral Gray surface alone."


Black Widow (...as well as CG-etc) started out with too much Aluminum. So there was issues to deal with. With the CG apps, it was primarily too much retro-reflectivity. With BW, the AAA introduced too much darkness of hue and granularity. The solution for both? Reduce the reflective element...either by bringing balance by the reduction of the amount of Aluminum, or the introduction of a higher ratio of masking component.


And the end result was ...in the balances that were achieved, more workable, useful DIY mixes. Straight up, only CGIII-IV really had/has significant retro-reflective gain properties. But also the caveats that accompany such.


Black Widow can really only lay claim to having taken a different, somewhat simpler route to achieve the "Contrast Enhancing" aspect that other DIY applications had already been providing quite handily. That much credit it is surely due. But in the saying of such it must also be related that there is a Brick Wall that looms up if too high a ratio of Aluminum is introduced....and that Wall is unassailable.


But none of that is to say that the use of metallics in the proper manner will always result in increased on-axis gain at the expense of viewing cone. That is simply not true


Mixes such as RS-MaxxMudd and Silver Fire contain over 200% more reflective material to Mix volume, yet still blended well, and performed in exemplary fashion. And....those apps had "Ear to the Screen Wall" viewing cones, and NO observable "half gain" tendencies. Certainly the latter was present to a "sensitively measurable degree", but by not being observable by the naked eye, the issue therein was irrelevant. Virtually all claims made to the contrary against the two apps listed above in this paragraph were self serving, rooted not in fact, but convenient supposition.


Even a simple Neutral Gray, it's hue matched to the PJ & environment, can and DOES perform nearly as well as a reflective-based mix, failing only at a lessor level of ambient light than a reflective-based mix can handle.


As I stated earlier, my main umbrage is with the offering up of statements alluding to what was espoused in the quoted missives. Perhaps if a more even handed approach at looking at ALL options was observed by those who continually advocate just one application over all others, such intervention would not be called for....or needed.
 

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There are some truths about a projection screen that can't be disputed. I don't offer my opinion here for MM or the others frequent posters, because I'm sure they understand these simple truths, rather I offer them to anyone new reading here hoping to gain some rudimentary knowledge into these maters. Some of the above postings attack these issues with some speculation and some very advanced jargon that could easily confuse a newcomer to this.


The first truth is that screens are a passive device and can not manufacture light. They can only return light or absorb light. But the laws of conservation of energy say the projector puts out so much and it all has to be accounted for in the end.


The second truth is a screen can direct light. Our screens fall somewhere between a perfect diffuser, a perfect mirror and a black body (something that absorbs all light) it can be thought of as a triangle if you want and if you move closer to one of the corners you are moving away from the other two. Where your optimal point is in the triangle is based around your projector, your room, your ambient light level, and lastly your preference of the type image you like to see.


The third truth is the human eye makes the absolute worst light meter to judge anything by. But by the same token it is our receptor of these beautiful images we desire. It is in finding the understanding of how our eyes work you will understand how a screen works. I wont go into what I feel IMHO this is but to be brief. The human eye has the ability to adjust 22-f stops (iris) while maintaining a somewhat constant point of reference of brightness to the brain. For those that don't understand f stops each one doubles the amount of light of the previous. This range is enormous.


Truth four , When you view a image off axis say at any angle but for talking and its been mentioned above 179 degrees, the image you view didn't change in height but the width is now just a sliver. The total light coming off the screen could well be diminished per unit area of the screen but we are receiving it compressed down to this sliver of light. Our eyes or the auto control on the cam we use to take the picture reacts to all this and it looks to be bright.


Truth five The colors we see when viewing an object (like a screen) are caused by the pigmentation of the surface we are looking at and the light striking it. In the case of screens our goal should always be a neutral pigmented surface. That being one like white that reflects the full projected spectrum equally. We have coined the term neutral gray as it has properties to attenuate some of the projected light equally and improves the dark colors being projected. It also lessens the light or bright colors in the exact amount. And it also attenuates some portion of the ambient light striking it. The two photos above show clearly how the exact same color of gray can look many times darker depending on the direction of the light striking it and where it is in the triangle I mentioned above based around the mirror like properties. Those can be surface sheen or those can be embedded metallic.


There are endless debates about what is white and what is black in an image and this is only my truth I believe, but it is totally a matter of perception. Caused by the state of our eye while viewing and how the brain perceives the image. I have posted countless images over the years how a gray can look inky black base around what it is in contrast with.


These are only my truths and I could be wrong
 

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Quote:
Originally Posted by bud16415 /forum/post/15570280


When you view a image off axis say at any angle but for talking and its been mentioned above 179 degrees, the image you view didn't change in height but the width is now just a sliver. The total light coming off the screen could well be diminished per unit area of the screen but we are receiving it compressed down to this sliver of light. Our eyes or the auto control on the cam we use to take the picture reacts to all this and it looks to be bright.


These are only my truths and I could be wrong

Bud,


Nope, your "truths" were well stated. Any possible exception would lie in the way the above quote could be interpreted.


Although I did use a impractical example in the attempt to illustrate a simple (...but true...) fact, the obvious real fact is that any retro-reflective screen that purports to direct a larger percentage of the light received directly back on axis toward the PJ's lens will suffer a marked reduction of light being directed "off axis". Can this "truth" even be questioned?


Barring the extreme example I offered, many such Retro-inclined Screen surfaces have their light output drop off appreciably (50%+) at 75 degrees off axis, while....eyeballed or not...no such indication of drop off at the Screen's edges has ever been related while using "most" properly mixed and applied Mica based mixes. If such had been, or was ever the case, I'm sure it would have been touted as a major failing thereof of such screens.


Just tain't never been sew.


And this in closing. The 179 degree "Sliver" of image as viewed would always give the advantage to the portion of the screen closet to viewer...even IF it contained to any degree the same...or close to the same amount of light being reflected from the Screen's center. But ONLY IF it did indeed have such an advantage. If it didnot, at best it would only match the apprence of the "center' of the screen. Remember that many earlier non-retro screens actually had a significant drop off of light output at their edges....often made all the more worse by PJs that had brightness uniformity issues. Simple reflective physics show that the light being directed back on axis would have almost no accentuating influence on light being scattered off axis if that "scattered light" was indeed attenuated buy broader dispersion, and was being viewed from so far off axis. Yes...Screens are passive devices...but that also means they are not so prismatic in effect that they could or would ever bend light to the point that such light bouncing back directly toward the PJ Lens would augment any light exiting the screen at a severe angle from center.


So very many illustrative examples of the "Half Gain" properties of both "Retro-" as well as "non-Retro" screens have shown that the loss of gain at the edges of a screen is deemed a universal issue.


That simple matte White surfaces exhibit the least of such manifestations simple drive the nail into the argument, ....er, discussion. Most Screen Mfg. have picked up on this desirable trait, and now post Viewing Cone specifications with as much importance alluded to them as the Gain and Contrast aspects of performance.


As do the issuance of "Clarity" and "Screen Transparency" specs....attributes first heralded on DIY postings. The Screen Mfgs are not totally dense...just wayward and slow in embracing any more "change" than the Market demands of them.


And my Brother DIY Forum Members....we ALL have made their lives more demanding for some time now....and even with the advent of spectacular performing 1080p PJs, we continue to show that the seeds of inspiration, combined with the needs of the budget, can result in envious performance values that they would be criminally myopic to ignore.
 

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Half gain etc are very hard to see by eye even though they do change the returning light a great deal.


Also the edges or corners of almost all projected images are a good deal less intense in terms of lumens than the center but once again our brain and eyes do a good job of blending and filling in the difference. When you switch a lamp from eco to torch mode take a look at the measured specs and then think about what increase in brightness you really see. Most people cant tell by eye a half a f-stop change in light and that is a 50% boost.


When setting up a projector we are always faced with where in the zoom range do we want to be. On some projectors there is quite a bit of brightness to be gained by doing this but by eye it's hard to tell.


It is very tempting to design by eye when fine tuning things but for my tastes if I can stay in what I feel is the 15 to 20 foot lamberts range with the known ambient levels I sometime want in the media room. And I can get that without needing metallic improved paints then to answer the OP's question, What is the purpose of metallic in screen paint? I would have to say none in my case. The image cant be improved past the best it can be IMO. If I were to want a 300 inch screen with my projector rather than 120 then I might just limit out on anything simple and then there would be a reason to maybe want metallic paint.


I have always said the screen selection starts with the projector selection and the screen size and room design. If you get a way out of wack combination then you will have to go to extremes with the screen.
 

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It's late! I had this on hand. Color is off, but you can see that the center is brighter than the sides. (I moved a section from the side over to the center for comparison.) I can take a better picture if needed. This is one of my screens that has some poly added for sheen. Notice also that all shades of gray are reduced, not just the whites. In a post that I deleted, I made the point that whatever you add to the paint to increase the whites will also lighten the close to black shades. Poly.... pearl... aluminum... doesn't matter. I get the feeling that many people may not realize that adding something to bump the whites is doing the same thing to the near blacks. This may sound like I'm knocking the use of poly, or metallics, but I'm not. I'm saying that if the selected shade of gray seems dim, then add some white rather than add more poly. Or add aluminum if you want, but realize that the dark grays become brighter along with the whites.




The gain charts posted in the first page of the "Beyond neutral gray" thread show that the Studiotek 130 screen brightness drops about 20% over a 20 degree angle This would be typical angle for a 1.5 to 1.8 screen width viewing distance. I'm not saying that this is a bad thing. I think it can be a good thing, and is just an example of what's occuring.
 

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The function of any reflective agent (with a higher reflectivity than the base mix) is to increase on-axis gain. If illumination is constant, on-axis gain cannot be increased except at the expense of viewing angle.


Garry
 

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Quote:
Originally Posted by prof55 /forum/post/15581558


The function of any reflective agent (with a higher reflectivity than the base mix) is to increase on-axis gain. If illumination is constant, on-axis gain cannot be increased except at the expense of viewing angle.


Garry


I thought that I totally agreed with you, but I got to thinking about it. If something like silver is added, it reflects and also diffuses light in some direction while absorbing very little light. If a mix of white and black pigments of an N6 shade was mixed, the black pigment would absorb a lot of the light, and reduce gain both on and off axis more or less equally. Adding silver, pearl, (or for that matter even more white pigment) to the mix would reduce the amount of light that the black pigment would have absorbed. Lets say enough white pigment is added to bring the mix to an N8. Gain would be higher both on and off axis than the N6 mix. Viewing cone would remain the same. A ball shaped highly reflective additive could still dispers light if it is basicaly round and if it spread out a bit with some translucent material, or white pigment, brown oxide, umber, red oxide, or whatever. So the end result would be higher gain both on and off axis relative to the N6 mix. Since the geometry is that of a sphere, I see no reason that it would reflect back stronger on axis than off, or do anything much different than adding white pigment. Or am I making a bad assumption? Now if the added material is more like a flake, and lays flat to the screen surface, then it would seem to me that it would increase the on axis gain at the expense of off axis gain and viewing cone as you stated above. Does this make any sense?


Did you perhaps mean that on axis gain cannot be increased above 1 without loosing viewing cone?
 

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You're right, kgbl. If the overall shade is lightened by the additive, gain may be increased across the viewing cone, up to 1.0.


If the particles were spherical, this would cover it, but I think the situation is more complex here. The additives mentioned (aluminum or mica) are in effect tiny flat mirrors, which by themselves would be unacceptable as a screen. When used in a mix, particle orientation plays a large part in the properties of the finished screen. The particles may lie flat on the surface of an opaque mix, be suspended in a translucent mix, or even be partially protruding from either mix. This particle orientation can vary widely, and is quite dependent on application method. Rolling tends to leave particles lying flat, and spraying a screen can give results that vary widely. Dry spraying actually leaves particles protruding from the screen surface in a fairly random pattern.


This also explains the very different results that occur when different folks apply the same mix. Rolled applications in an opaque base are the most consistent. Spraying is quite dependent on operator skills - or ability to follow exact spraying instructions. Either will work, but in both cases a person has to have some idea of what the screen surface should look like.


To me, the best mix is one which will give the same basic results with the widest range of application techniques. Of course, there's nothing wrong with becoming an expert screen painter, as long as you realize that others may not be able to reproduce your results. BTW, Maurice - I'm not directing that comment at you, lol. I'm just enjoying the conversation, and getting somewhat OT.



Garry
 

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Quote:
Originally Posted by prof55 /forum/post/15587140


You're right, kgbl. If the overall shade is lightened by the additive, gain may be increased across the viewing cone, up to 1.0.

I've seen that pushed up a few extra percentage points (1.2 - 1.4) by correct spray application and still maintain enough dispersion that neither obvious retro-reflectivity or hot spotting occurs.


Is it just me? Surely not!



Quote:
To me, the best mix is one which will give the same basic results with the widest range of application techniques. Of course, there's nothing wrong with becoming an expert screen painter, as long as you realize that others may not be able to reproduce your results. BTW, Maurice - I'm not directing that comment at you, lol. I'm just enjoying the conversation, and getting somewhat OT.



Garry

I caught it's gest though!
Dependable and consistent results are more easily achieved these days using simplistic application methods that equipment, such as the Water-Thinned DIY Paints and the Wagner Control Spray can provide.


Well, and also following a few basic directions.
But that's why I hang around....to help those who need such ministration. Nothing beats a heartfelt expression of thanks from a Happy Projector Head. That's the single most valued common denominator most all of us share.



It's all good if a good effort is made by all. Otherwise.....
 

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Quote:
Originally Posted by prof55 /forum/post/15587140


You're right, kgbl. If the overall shade is lightened by the additive, gain may be increased across the viewing cone, up to 1.0.



To me, the best mix is one which will give the same basic results with the widest range of application techniques.


Garry

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.

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 hotspotting. 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.


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.
 

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Quote:
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.

Quote:
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.
 
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