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A darker Black Widow?

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darker widow
4K views 24 replies 5 participants last post by  Ericglo 
#1 ·
What would be the recommended method to make Black Widow a bit darker?

I am pondering getting the new Acer H6500 projector which has good light output and I would really like to have some ambient light tolerance.
 
#2 ·
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:).
 
#3 ·
Thanks Harpmaker. Is that "Ivory Black" the same as a bone black pigment?

If you use up to 10% of the Ivory Black, what gain do you expect to achieve? BW is around 0.88, but what if I want to get down to 0.4?

Have you looked into black mica pigments? "http://www.amazon.com/Dark-Black-Mica-Powder-Metallic/dp/B0040E981E" (sorry, can't post auto-links yet, only 2nd post)

How about a darker base coat?

I know, lots of questions, but I like to explore the possibilities. :D
 
#6 ·
Maybe a very dark neutral balanced OTS like Glidden Onyx Black would be useful.
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!

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.
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 ;)).

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.
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.

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.
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.

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.
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. ;)
 
#7 ·
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!
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.


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.
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.


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.
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.


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. ;)
Past experience? Sure. I'll be open and transparent about my past :D 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.

In the process of doing that a couple of "enthusiasts" (I use the term loosely) came over from AVS wanting to also do some work on the idea. I stuck with the idea of using no to little titanium dioxide pigment. One of those AVS individuals pushed the idea of titanium dioxide, essentially turning it into a silver/pearl/TiO2 paint balanced with color components.

When I saw that I figured I could just go to the paint store and find a proper balance to the color pushes of silver/pearl. I backed out of the patent attempt because I knew it was a waste of time and didn't have any new science behind it and would be rejected on review.

Even after backing out, I negotiated to get a small cut of any proceeds but an official agreement was never completed, not for lack of trying on my part. I suspect some money was made but I never saw any of it, probably due to the debt incurred from the patent prep.

Anyways, over the last 5 or 6 years I've been mulling ideas over and over in my head without a projector to really play with. Hopefully that will change soon. Time to stop lurking in the shadows. :sn:

If you have any questions, I'm open to answering whether they be technical or about my past experience.
 
#10 · (Edited)
...and just to pique your interest...

These screenies were taken during 2005 (I believe :dontknow:) 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.







Inspiration for a new avatar :eek:
 
#13 ·
Ok, I ordered a new projector...ViewSonic Pro8200, one of the sub-$1000 1080p DLP units. A review at Projector Central states that it puts out 1145 lumens in the "Dark Room" setting in low lamp mode. I intend to run with these settings, or something close to it, to extend the lamp life. The projector will be ceiling mounted.

I intend to have a 92" diagonal 16:9 ratio screen. This would give me 45.5 footlamberts on a unity gain screen.

I want to use Black Widow, but with a gain of 0.88, it would give me 40.1 footlamberts.

Based on previous posts, my plan would be to paint a darker neutral gray base coat and then paint a top coat of Black Widow.

Any suggestions for the neutral gray base coat? How dark do I need to go?
 
#14 ·
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.

To get a darker BW™ screen you need to darken the base paint used to make BW™. If you are interested in trying such a mix I'll start a thread in the DIY Screen Development forum. This experimental mix would be N6.6, have the same amount of aluminum in it and would be neutral.

With so much light hitting your screen you don't really need a reflectively enhanced mix like BW™, an OTS neutral gray would work fine. A paint tinted to match Glidden 'Veil' (~N7.5) would work well. Whenever you use a reflectively enhanced mix there is always the possibility that you may see some graininess in the image depending on the brightness of the image and how close your viewing distance is.
 
#19 ·
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.
 
#21 ·
I doubt it. If you take a look at the spectrum analysis done here on Silver Fire, you can see that the peaks and valleys are in the wrong places. I realized a month or two after my initial trials that there really isn't a good combination of pigments to put peaks right at R,G,B wavelenths and valleys at all other wavelengths. The spectral responses are too broad. With the addition of Cyan, Magenta, Yellow and "White" color wheel segments on DLP projectors, it's a futile exercise.

I'm surprised that the AVS'ers haven't been clever enough to mix a purple pigment (red and blue reflected) and a green pigment to cut down on the number of different pigments in their mix. This is something I looked into years ago but couldn't achieve the peaks and valleys that I wanted so I never disclosed it to the DIY world. However, this idea could possibly be used to achieve a neutral color balance.
 
#22 ·
I'm considering a projector for a small room that probably isn't really suitable for one, but I'm hung up on the idea of a 2.35:1 screen to ensure that movies are suitably immersive - my concern with a plasma is just that you get used to the size and then movies still seem small even though it would be a substantial improvement from where we are now.

My problem is that the tiny screen results in very high ft-L values - 24 in 2.35:1 config and if I zoom out to 16:9 I get 35+. So, the idea of a darker BW screen is intriguing. Paint is cheap so I do intend to try one of the identified neutral grey colors, but the additional ambient light rejection of the BW formulation is still attractive.

Being a projector newbie I'm hoping that dialing down the contrast as part of a calibration pass will help, but I'm not sure whether that's really possible without crushing things.
 
#23 ·
I understand the desire for 2.35:1. Thought about going the same route. However, I am hoping that the darker BW™ N6.4 will render the annoying top and bottom "black" bars, much less annoying than on a traditional screen. Then I won't have to mess with zoom or an anamorphic lens setup.:D
 
#24 · (Edited)
For me, 2.35:1 is pretty much the entire lure of a PJ - it's not that I mind the bars, just that I want to prioritize the 'wow' factor to movies. A 2.35 CIH setup allows me to do that, and actually suits our limited space very well since we actually have more width than height.
It'll be a bit of time before I can get around to screen samples, but I'll switch over to the 'development' thread since I definitely think I'll try out the darker version in addition to the standard. Ordered the PJ (Mits HC4000) yesterday, but I don't expect to get much more than DOA / sanity check with the wife done in the next couple weeks due to a busy schedule.
I plan to try to spray this with my Earlex HVLP rig, but it'll be my first experiment with it so it may be a disaster
 
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