Would that member be me :bigsmile:
From what I see you're only using .27 ounces of the Pearl Silver for a quart of the main mix. That's why you don't see a color shifting. That's less than 1% of the entire main mix. The other 'popular' pearl/poly topcoating mix uses 2-4 ounces of craft grade mica. That's 6-12% of the entire mix, and a significant difference. And if you agree that is a big difference, BW PFG uses a whopping 20% of the aluminum component for a 40oz mix. I'm positive if we had 20% mica/pearl in any mix it would be unwatchable.benven said:On another note, what is the difference between using aluminum flakes and the silver mica flakes that I have been using? I easily attained a neutral, or really close to neutral, paint mix with them.
Unmolested neutral gray in a flat or matte finish is naturally around a .8 or lower gain depending on how dark of a shade it is. Going from .8 to .9 is pretty easy. Getting to 1.0 from say a .8 surface gain starts to have an effect on things, but still not enough that the average person would notice. Going from .8 to 1.2 and the viewing cone not only starts to become noticeable, but specular gain starts to overtake the native 'gain' of the shade of gray alone. Once you breach a .5 increase in gain viewing cone starts to drop faster and off axis color shifting becomes more apparent unless careful steps are taken to counteract the color shift. There are no known steps that can compensate for viewing cone as gain goes up, well not totally true... that's when a torus screen comes into play... It is however true when it comes to flat screens.benven said:Not to nit pick. But 0.8-1.2 is a 50% difference in gain!! That alters L alot. If we say unity gain +/- 5%, that would make more sense to me. That isn't too difficult to hit. It just seems pointless, to me, after doing all that work to get a neutral gray that you would ruin it with such a gain spread.
Even with a DLP that just has an RGB color wheel, it is additive color. All colors combined create white in an additive color system. With paints it's a subtractive system and when you add all colors you get black.I have a question about the prism effect of mica: Since my PJ only has red, green and blue filters on the color wheel, in theory (there's that word again :bigsmile, I shouldn't see any prism effect even if it is present because no "white" light is hitting the screen.
Do most of the more expensive, or better, PJ's have a white (or clear) section on their color wheels that this is so important?
From what I see you're only using .27 ounces of the Pearl Silver for a quart of the main mix. That's why you don't see a color shifting. That's less than 1% of the entire main mix. The other 'popular' pearl/poly topcoating mix uses 2-4 ounces of craft grade mica. That's 6-12% of the entire mix, and a significant difference. And if you agree that is a big difference, BW PFG uses a whopping 20% of the aluminum component for a 40oz mix. I'm positive if we had 20% mica/pearl in any mix it would be unwatchable.
As far as aluminum over mica- One is a non-interference, the other an interference method, which is another factor and why I was so interested in it.
With lighter colors micas are a bit more forgiving but color shifting is still there. When things go darker color shifts are more apparent.
This is just a fact of what mica (pearls) do. It's why they are used by artists. Non-interference materials are opaque and do not allow light to pass through them, so the light is not refracted. Mica is a trade off that's been used for years. It makes for a brighter image, but causes color shifting. Aluminum (non-interference) also creates a brighter image but doesn't have the classice mica rainbow color shift effect.
What they say is true but you have to keep in mind we see a complex image that is produced by the projector. In order to see the image and colors, mirrors are turned on and off to control the pixels, and the color wheel sends the light. To get a color other than red, blue, or green it rapidly passes light through different color segments. Our eyes combine it into the 'color'.Thanks for the reply Bill. I want to be clear that I'm not being argumentative either, really, I'm just trying to understand this correctly. onder:
Great treatise on iridescence! :T
Perhaps Texas Instruments is simplifying the matter too much, but their explanation of how a single-chip DLP projector works ( http://www.dlp.com/tech/what.aspx ) says, in both text and graphic, that the DLP chip is struck by only red, green and blue light (the light that passes through the color filters on the color wheel), thus only red green and blue light hits our screens using such a PJ, and only one color at a time. It is the "persistence of vision" of our eyes that makes us see the full visible light spectrum. As I'm sure you know, it is the same phenomenon that lets us watch a CRT television without seeing the even and odd scan fields, but rather one image that doesn't flicker.
If what T.I. says is true, I don't understand how iridescence can come into play with such a PJ. :dunno:
You have MUCH more experience with this stuff than I do, and if you say iridescence is a problem I believe you.
The next time I have my PJ in my "lab" I'll do some testing and see if I can work this out so I finally "get it". :nerd:
One thing to note is the Micro Pearl seems to be a much finer size of flakes as compared to the craft paint pearls. I think that is the biggest factor right there, better quality.Thanks Bill. I guess I should have explained myself a bit better. I should have stated....what is the difference between aluminum and silver mica when put into a paint mix or media? The refractive properties of coated mica flakes and the reflective properties of aluminum must change. I have no scientific proof of this. But using common sense, when mica flakes are mixed into a paint or some other media, how do their properties change? The refractive properties would have to b e different? mech has stated he did not see the prism effect with the mica powders I have used. I assume the reflective properties of the aluminum flakes change. Maybe this requires more discussion/investigation.
And yes, my bad mech, I shouldn't have hijacked this thread :sneeky:
Prof, here's an Australian place to get Auto Air...it ain't cheap at about $40 (+shipping, I assume)...but should be enough for 2 screens. Maybe you and Kane could split it (if it's cost effective to mail paint to each other)???Short answer Bill...NO..
As I mentioned recently, you can't ship any canned paints into Aus. or post between States in Aus., without a special permit, reserved for importers and distributors..
Within Australia, you can road deliver paints between States but it can get expensive for just a couple of cans..
Kane who is in New South Wales and me in South Australia, would need to be able to access the same brands of paint to maintain the correct colour base, plus the same alum. additive..
WOW!!!...Thanks for that Bill..and they are based in Adealide!!:unbelievable: :yay: