Welcome to HTS! :wave:
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Thanks Harpmaker. Is that "Ivory Black" the same as a bone black pigment?Welcome to HTS! :wave:
While it's possible to darken BW™ a bit by adding Liquitex BASICS 'Ivory Black' (a max. of 10% IIRC), we actually are in the process of developing darker versions of BW™. However, it a slow process since we have to do it in our spare time and that is at a premium nowadays (life seems to speed up not slow down :gulp
Yes; the other major black pigment in artist acrylics is 'Mars Black' which is a synthetic iron oxide. 'Ivory Black' will result in a blue push to the mix if too much is used and the blue isn't corrected for, but it is less blue than 'Mars Black'.
Unfortunately, screen gain isn't something that can be guessed with any accuracy at all; too much goes into what produces it. First you have the gloss level of the paint base being used and then you have the added gain from any reflective element added to the mix. I could tell you what gain (or rather how much light the surface would absorb) for a Lambertian surface (a surface that reflects light in all directions equally), but when you throw paint gloss and reflective particles into the equation gain simply must be measured. It turns out that a N7 Lambertian surface would have a gain of 0.4 (would reflect 40% of the light that hits it). A N7 neutral gray paint, even most flat finish latex paints, would have a gain slightly higher than this since even they have some gloss. The more gloss and/or the more reflective particles that are added the higher the peak gain of the mix will be, but it doesn't take much to be too much and then hot spotting, or other negative optical artifacts, becomes a problem.
Yes, but when you start adding color to mica you decrease the reflectiveness. This is from the description of the pigment you give the link for: "This mica powder is a matte with a very slight shimmer". All the colored mica powders I have seen are either for coloring automotive paint (thus having large flakes that won't work for a screen) or making cosmetic powders (these lose most of their reflective qualities when added to paint).
This is the way we will try to go with our darker BW™ mixes.
We don't mind questions, questions are good. :TI know, lots of questions, but I like to explore the possibilities.
Maybe a very dark neutral balanced OTS like Glidden Onyx Black would be useful.
Understood. It's a delicate balance of specular reflectance and Lambertian. The aluminum is really working well then to provide a gain of 0.88 and a Munsell value of 7.5. It would be nice to be able to achieve a paint with a gain of around 0.5 but a Munsell value of 4 or so. With today's light cannons, this would still provide a nice image in ambient lighting.
Yep, I haven't been able to find any reflective "black" pigments that retain their reflectiveness.
So, does this mean that you will need to make BW more transparent? I've been thinking about a dark neutral base coat that is glossy, covered with a topcoat of flat transparent BW. I imagine that the struggle will be finding the correct tinting additions to keep it neutral.
Thanks again Harpmaker. I will do what I can to ask more questions and provide input when I can. I've got a little experience in these matters.
If that color was truly RGB 30 then it would be perfect, but my experience is that as grays get darker they are harder to keep neutral. I'll get a sample of 'Black Onyx' next time I get to a paint store, thanks for the tip!
Yes, it's a combination of the aluminum and the gloss from the latex base paint. Most BW™ mixes we have measured have been ~N7.6 which has a Lambertian gain of 0.5. (0.499 if you're picky
).An N4 paint would have a Lambertian gain of 0.11, I would guess getting that up to 0.5 without hot spotting would be tricky. Another problem that raises it's ugly head when mixes get darker is "simultaneous contrast", this is the contrast difference between the lightest and darkest areas of the screen. Think of it this way, the contrast difference between a white and a light gray is a lot less than between white and black. In the real world this difference can show up in a number of ways, for screens it's usually an appearance of graininess or a filmy layer on top of the screen that may or may not shimmer in light scenes.
While I won't take any technique "off the table" at this point, I doubt very much if increasing mix transparency is the right way to go especially if the mix contains reflective particles. While a transparent/translucent BW™ mix would allow light to reflect off aluminum particles below the surface of the screen those same particles could also block the light from the deeper flakes from escaping in a direction the viewer can see. It could also set up a condition where light reflects internally several times before either being absorbed by the screen or exiting on a plane that may or may strike the viewer eyes. This is one of the reasons why the so called "light fusion" screens advocated on another forum don't really work as advertised.
No problem! :T Would be share your past experience with us? If for any reason you don't want to do so publicly, feel free to PM me.
I don't have the RGB for Onyx Black, just know it's from their neutral palette and is probably around an N3. I was looking through the Sherwin Williams colors and found Tricorn Black (SW 6258) which is 45 45 46. Not quite the 30 you would like but not bad either.
Well, you guys did really well getting from a Lambertian gain of 0.5 up to 0.88, but I'm sure making it darker it can be accomplished.:T I understand what you are saying about the contrast but hopefully more modern light cannons can overcome it.Yes, it's a combination of the aluminum and the gloss from the latex base paint. Most BW™ mixes we have measured have been ~N7.6 which has a Lambertian gain of 0.5. (0.499 if you're picky
An N4 paint would have a Lambertian gain of 0.11, I would guess getting that up to 0.5 without hot spotting would be tricky. Another problem that raises it's ugly head when mixes get darker is "simultaneous contrast", this is the contrast difference between the lightest and darkest areas of the screen. Think of it this way, the contrast difference between a white and a light gray is a lot less than between white and black. In the real world this difference can show up in a number of ways, for screens it's usually an appearance of graininess or a filmy layer on top of the screen that may or may not shimmer in light scenes.
All of your concerns are legitimate. I remember looking at the screenshots of light fusion and thinking that they looked "murky" or out of focus. If I can get around to getting a new projector, I would like to push the limits.
Past experience? Sure. I'll be open and transparent about my pastNo problem! :T Would be share your past experience with us? If for any reason you don't want to do so publicly, feel free to PM me.
I don't know if you or anyone else recognize my screen name from the Lumenlab forum. I was the guy who pushed the experiments utilizing colored pigments to create much darker screens, and I was working with a low lumen DIY projector.
It's not odd at all. I've watched what the other forum has become. I prefer liberty over tyranny
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of my version of a black screen. This formula used silver and pearl mica based pigments plus various red, green, and blue pigments. There is NO titanium dioxide in the mix. Behr flat deep base was used to carry the pigments. This coat was spray painted over a standard primer coat. The projector is a LL style DIY job pushing maybe 250 to 300 lumens, floor mounted. Black screen is on the left, BOC on the right. First pic is with lights off. The "lights on" shots are obvious. The boxes holding up the screen are 18" wide so that puts the diagonal measurement around 75". All of the ambient lighting was coming from the right side of the screen. Pictures were taken from a seated viewing position (AKA on the couch:bigsmile. I hope I remembered everything...was 6 years ago.
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Yep, they all have different Spectral Power Distributions.
I made the mistake of reading "base coat" as "base paint" before, sorry about that. The color of the base coat (the paint that BW™ will be applied over) will have little to do with the appearance and performance of the BW™ screen. All of our mixes are as opaque as we can make them so very little light makes it through 2 rolled coats (~4 sprayed coats) of paint.
Base Coat vs. Base Paint...yeah, that threw me off.:doh: I understand what you are saying now and it made more sense to me from the beginning to darken the base paint. What you are saying is that you need to make the Bermuda Beige darker and properly formulated so that when mixed with the AAA the reflectivity will be increased and the color will be a neutral balance.
I remember that. I believe the conspirators made a big deal of going over to LL before they returned in force to AVS....and just to pique your interest...
These screenies were taken during 2005 (I believe :dontknow
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Eric, Unfortunately, that screen is long gone and I haven't been able to locate the exact formula since the LL website is now non-functional. That screen was far from perfect but showed that a very dark screen could work well, even with a low lumen beamer.
No, I haven't dismissed it totally, but one also has to consider the color of any ambient light sources and how they will reflect off such a screen. That is what makes the problem more complex and from what I know now, likely impossible with the available range of pigments. However, if you can filter certain wavelengths out of your ambient light sources...then maybe...but that is another can of worms altogether.
