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Discussion Starter #1
Hi all,

I'm rather new here. I see that there are resonably much work done here on "non-white" DIY paint screens.

My problem is that I have a rather "all-in" home cinema room. Black long haired carpet, matt black walls, black cloth around the picture, full light control in, etc etc

On the wall I just took the paintshops most expensive high quality matt white wallpaint. After doubting wether this actually could be good, I ordered home a couple of test sheets (all white) from the local video screen dealer. To my surprise I could not see any difference. The only one standing out was the high gain one, but that one shimmered anoingly.

Now, engineer as I am, I just can not believe that of the shelfe white is the best there is. So I called a large scandinavian paint producer. Now they say that the paint industry utilise one version of titanium dioxide as pigment for white. And that can be bought by the kilo in artists paint shop. Then he said that they produce different pigment pastes for obtaining the different NCS standard colors. And yes, they produce white pigment paste. Now if anything is white, that must be it. Its like super concentrated white.

So I kindly ask you, after getting the matt "mega-white" up on the wall, is there anything else I can top coat with to get an even better picture? And in that case, what parameter can I achieve to improve with a top coat of some sort?

And of course, the underlying question. If I am after a near 180 deg viewing angle screen in my "near perfect lighting" cinema room....Is a painted white wall as good as a white screen ..say from Stewart or Da-lite?:ponder:
 

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Re: White...were are you?

the search for a truly white paint has been going on for a while.
most white paints are slightly yellow in color (deficient in blue).

myself, harpmaker and mech have actulally color tested some of the artist whites that you refer to. the titanium whites we tested seemed deficient in blue again:dontknow:
the results can be found here.

if you are looking for a perfect 180 viewing angle then why change the properties of the flat paint with a topcoat?
 

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Re: White...were are you?

The thing with white is, and this is all my opinion here :dumbcrazy:, most of the new projectors coming out nowadays have moved beyond white as a screen. If one were to survey home theater users I'd guess the majority would place blacks and contrast above 'pure whites' as a priority. That and the fact that most new projectors have enough lumens to burn your eyeballs if you used a white screen. Consider the 12fL standard for a pj screen. If you went out and bought a new Mitsubishi HC6500U with a nice 106" screen of unity gain, you're at 15fL. A Panasonic PT-AE2000U would give you 17fL. And I've had folks asking for recommendations when it's even up in the mid 20s. :yikes:

So yeah, there's not much for whites. And that's a testament to the fact that just a basic matte white from your local paint store will do just fine. :T And while we've only seen one white that was flat spectrum wise (a Dulux product in New Zealand), whites are much more forgiving picture-wise than a gray that's not neutral. wbassett taught me that! :bigsmile: And I believe that just about any matte white should match up pixel for pixel with a unity gain screen material. It's when you want to go beyond that when it gets tricky! :dizzy:

There are several artist white spectro readings in the diy screen developers forum. I'd bet you can get some of them where you're at. We are just starting to crack that nut though, as well as other nuts.

As for topcoats, that's yet another nut to crack. :bigsmile: And at this point in time I can recommend nothing to topcoat your screen. Polyurethanes yellow and discolor your paint as well as added unneeded other detriments. I have some good ideas about a topcoat, but nothing's been tested yet. Too many things on my list and not enough time. :wits-end: What is it you're looking for in a topcoat? Protection? More gain?

A painted wall can be as good as a unity screen from Da-Lite or Stewart. But once you start talking firehawks and high powers, I don't think so. There are people who think you can... just not me right now. I reviewed the Elite Silver Screen here at the Shack and if they would have sent me a 100" model I'd still be using it today. Instead they sent me a 92" model so a local church has it now. Occasionally I contemplate buying one. They're only somewhere around $500 US here right now and that's pretty cheap for a nice quality product. Enough of my musings! ;) Keep reading and ask away. We're here to help! :T
 

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Re: White...were are you?

Hi Robert,

Color Science is an amazing subject. Most of what we are taught in school about how color is derived, perceived, and especially mixed, is either flat out wrong, or so simplified that we have a very incomplete understanding of it. I got interested in DIY screen paint mixes a little over a year ago and it has been a wild ride ever since. I learn things every day either by actually mixing paints and taking readings of them with my spectrophotometer, or by reading books or material on the internet about color science.

To be candid, Titanium dioxide is not pure white. It is a "bright" white, and is very opaque, but it doesn't reflect all colors equally (which pure white would). TiO2 is a "warm" white meaning it reflects the red and yellow portions of the spectrum better than the blue and violet. This can be seen in the Spectral Charts Custy linked to. In the house paint industry, this works to a homeowners advantage since, until florescent lighting became more prevalent, the incandescent lights we used in our homes are also "warm" light sources and are heavier in the red-orange end of the spectrum in their output.

As far as projector screens go, we want to have as neutral color a screen as possible. This ensures that the colors reflected back to us from the screen are the same as the colors the PJ shoots the screen with.

To date, we have found no truly white house paint, or even artist paint. Custy (who is in the U.K.) found a neutral white house paint, but the same paint by the same company sold here is the U.S. (Dulux) has the same spectral qualities as other U.S. white paints (I suspect this has to do with laws governing materials used to make the paint).

To answer your question; no, there is no top-coat that you can put on your white painted wall to give you a better picture AND retain a 180 degree viewing cone. The way a screen is made to appear "brighter" is to increase it's reflective qualities either by adding gloss or a metallic ingredient. Both of these methods decrease the viewing cone of a screen a little bit. It is simple physics, only so much light from the PJ hits the screen. If the viewer closer to the center of the projection axis sees a brighter image that a matte screen of the same N value provides, it MUST take that light from the off-axis areas of the screen.

In many cases we don't need a lot of "boosting" of the screen output to make a visible difference in it's perceived white-level. Mech is finishing up doing some amazing screen gain tests that show that Black Widow (a reflective gray screen mix here) loses very little brilliance off-axis while giving a good increase in white-level.

One of the best paint solutions for a home theater such as yours would be a mix called Cream&Sugar (which has it's own thread here). I simply added a silver metallic paint to one of the more neutral white paints sold in North America until it was neutral in color and showed some reflective qualities from the added metallic. This, however; dropped the paint from a Munsell N9.7 to N9 (N10 is pure white, N0 is pure black). The problem with recommending C&S to international users is that the metallic paint used is only available in North America.
 

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Discussion Starter #6
Re: White...were are you?

the search for a truly white paint has been going on for a while.
most white paints are slightly yellow in color (deficient in blue).

myself, harpmaker and mech have actulally color tested some of the artist whites that you refer to. the titanium whites we tested seemed deficient in blue again:dontknow:
the results can be found here.

if you are looking for a perfect 180 viewing angle then why change the properties of the flat paint with a topcoat?

I am speech less...:rubeyes:...the ammount of data you guys have here...
 

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Re: White...were are you?

=> Harpmaker

So you recommend C&S. Have C&S been measured in gain-angle-profile?

I saw somewere that some one have researched a NSC code for the base? Cos I guess I could order the silver additive on the net and let my paint shop guy give it a go in the shaking machine.

Maybe the first C&S installation in Sweden? :bigsmile:
 

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Re: White...were are you?

=> Harpmaker

So you recommend C&S. Have C&S been measured in gain-angle-profile?

I saw somewere that some one have researched a NSC code for the base? Cos I guess I could order the silver additive on the net and let my paint shop guy give it a go in the shaking machine.

Maybe the first C&S installation in Sweden? :bigsmile:
I guess, for your HT, I would recommend C&S. It is the lightest neutral reflective paint solution I know of. While N9 is technically gray, it is a very light gray.:nerd:

No, C&S didn't make it into this round of gain tests (we simply forgot!:hide:), but I strongly suspect it will have a similar gain profile as BW.

One of the "problems" with C&S is that the base is so light in color that the paint stores I have tried to have it matched at try to sell me regular white paint instead. The color is literally so close to white (as far as housepaint colors go) that the computer doesn't want to try to match it.

See the second post in the C&S thread where I address searching for a Craft Smart Metallic Silver replacement outside the U.S.. I believe that Delta Ceramcoat paints are sold in many countries; if you can find them in Sweden, Delta Ceramcoat Silver Metallic is the paint we are trying NOT to match. This silver paint shows the "prismatic effect" I speak of very clearly. We are seeking a silver paint that doesn't show that effect.

By the way, I tried using the Delta paint in making C&S and it didn't work at all! Even with a ratio of 1:1 (50% silver paint) I could see no sparkles in the mix.

It would be fantastic if you could find a local replacement for the CSMS. If that were done, I'm sure we could come up with a base paint to add it to. :T
 

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Re: White...were are you?

Another hearty welcome to the Shack Robert!

White is by far the easiest of all screens be it DIY or commercial. That is if it is at least somewhat close to being white. As mentioned a lot of white house paints have a bit of a yellow/cream color to them, and the reason is simple- It softens the look up and makes it more appealing to a wider range of people painting their walls. A pure white (or as close to 255 as possible) would look really bad as wall paint. Pretty much it would make your house look like a laboratory or hospital.

There are brighter whites out there, but then things usually go in the other direction, which is a lot of manufacturers add blue to make it 'appear' whiter and brighter. Think laundry detergents that add bluing agents to make whites seem whiter. Usually these paints are used for trim work and accent work an not for an entire room.

Now for the good news... White is very forgiving as a screen. It can be off from a pure neutral white a bit and still produce very accurate colors from the projector. The reason is because white doesn't absorb as much of the projected light as a gray screen does, so it doesn't have a color lean, or at least not as bad and it can easily be compensated for at the projector via calibration.

As we go darker, more light is absorbed by the color. If the gray is not neutral the color push is more previlant than the white screen because less of the overall projected light is being reflected back. That's why with grays remaining neutral is really crucial to a good screen.

Now to the question of is there any better? Many will argue that yes there is, but honestly when we're talking about white screens, other than gain or things like that... no not really. Projector manufacturers QA their projectors to a plane jane unity gain white screen. So a 1.0 unity gain white screen will provide an image exactly as the projector is producing it.

From there the next item is brightness, or fL. The minimum for a room like yours is 12fL and THX standards bumps that up to 14 fL for a slightly brighter and vivid image. More than that in a dedicated HT room like yours and you start getting to the area where eye fatigue occurs or even headaches. Gain is probably one of the most misunderstood aspects of a screen. It is a tool to achieve the required brightness for the room setting, projector brightness, and screen size and that's pretty much it. Some people do like higher gain screens because to them they are more vibrant, and that's fine because they are entitled to their personal opinion. A lot of these people also like the wow factor of the display sets at the big box stores, which all have the brightness and colors pumped up so far they are over saturated and not realistic, but at first glance they really grab your attention.

With all that said, to 'improve' the image we see on the screen, a lot of people diviate slightly from a bright white screen. I will not deny or debate that a white screen is the most accurate across the board at reproducing colors of the projector's image, but if the projector doesn't produce true blacks, and most don't because of the nature of the technology used, then the image will never look like that of a CRT or top of the line plasma/LCD HDTV.

One way to improve the image is to 'trick' our eyes and brain into thinking the blacks are really black. This provides a better perceived contrast to the image. Keep in mind you can never exceed what the projector is capable of putting out, but we can trick ourselves into thinking the image is better.

This is where gray comes in. As the guys mentioned, not all gray screens are dark gray like a Firehawk. Conversely most are a very light gray. Interestingly most commercial screens that are sold as a 'white screen' are closer to N9 than 255.

You asked about top coatings. Primarily they are used to either add sheen (poor man's version of gain) or to knock down the specular gain and make the screen more diffusive (that 180 degree viewing cone). As gain increases, the viewing cone decreases. There is no debate about that, it's part of the characteristics and physics of light. (You can't create more light than was originally produced... just redirect light energy from the off angles towards the viewing area... i.e. viewing cone decreases). So unless you're hot spotting, which it doesn't sound like you are, or if your screen brightness is less than 12fL, again doesn't sound like the case... there's not too much more you're going to do. Pretty much you proved that by comparing commercial screen samples.

I also would recommend Cream&Sugar for your setup. I know that was a long winded way of saying that, but I wanted to explain exactly why I came to that decision and not sound like I was just recommending something because it is popular or just for the sake of recommending it. I'd make up a test panel though and compare it to what you have now. It is light enough that you can do a side by side comparison and get an idea whether it is improving the image or not. What you should see is better blacks, which in turn will make your percieved contrast ratio appear better too. The very light shade of gray (again, most people think an N9 gray is white) and the added gain of C&S should add to the image depth as well.

The beauty of all this is a person can test out a variety of screens and if they don't like something, they can easily just repaint back to what was the most pleasing to them. In this respect you can try out different screens and by the time you decide on your permanant one, you won't even come close to the expense of even an inexpensive commercial screen. That's something DIY definitely has over the commercial realm. It's not exactly easy to buy a screen to test and if you don't like it simply return it... it doesn't work that way with commercial screens. Even if they take it back, there is usually a restocking fee, many times that can be more than the cost of the DIY alternative. I even recommed this method to people only interested in a commercial screen and not DIY. This way they can fine tune and 'dial' in the ideal shade of screen that bests suits their needs, and then they can buy a commercial screen in that shade with confidence they will enjoy it.

Last thing I'll add is I always tell people to calibrate to a white screen and to spend a week viewing various content before they try other screens or DIY methods. Without doing this a person will never know if they really improved things or possibly made them worse. You already have that step done so you're ahead of the curve. In the end you may find what you have right now is your cup of tea, if not... try a little Cream&Sugar to sweaten things up just a tad! ;)
 

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Re: White...were are you?

I bow deeply in awe of your wisdom Bill :clap: (and of course everyone else here not forgotten)

Thank you for a very good explanation. One question though Bill, when comparing an alternative to my present white wall I should recalibrate the picture to the new one, right?!

I mean a side by side is good to see how they differ, but tbh imho the correct way to compare is to test each screen at its own peak caibration.

Comments, thoughts?
 

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Re: White...were are you?

I bow deeply in awe of your wisdom Bill :clap: (and of course everyone else here not forgotten)

Thank you for a very good explanation. One question though Bill, when comparing an alternative to my present white wall I should recalibrate the picture to the new one, right?!

I mean a side by side is good to see how they differ, but tbh imho the correct way to compare is to test each screen at its own peak caibration.

Comments, thoughts?
That is correct. The PJ should be calibrated to each screen for testing that screen, even in side-by-side comparisons. Depending on the individual model of PJ, the setting might not change much (or at all) from a white to a very light gray screen, but small changes make a difference. We have a saying (I think it's world-wide) that "The Devil is in the details".

One thing to be aware of is that in literal side-by-side testing (one PJ image on both screens at the same time) the white screen will always have the whitest whites and the gray screen will always have the blackest blacks. Usually, the gray screen will also have the more intense colors (at least in my limited experience).

We can see "white" on a gray screen because when that screen is the only thing being illuminated by the projector it is the lightest reference our eyes and brains have. We see an image that contains something we "know" is white, such as snow or a white dress, and our brains compensate for the "real" color being gray and we see it as white. It is a form of optical illusion, but it works in our favor. What a gray screen takes from the whites, it gives to the blacks; this is why we say a gray screen aids or boosts contrast. It really doesn't improve the contrast of our projectors, but it, in effect, slides the entire contrast scale down a notch. This is another reason why PJ calibration is so important.
 

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Discussion Starter #12
Ok,

I whent out to the local crafts shop with tons of artistic stuff. We identified two main sources of silver paint. And after taking a few drops of each, it was clear that one gave a shine in rainbow colors and the other was kind of "pure silver" shine. So reading your "rational" I took the later one. I bought 250ml to begin with. It was expensive compared to "normal paint". 250ml costed almost 8 pounds. The "silver" is very fine, you can hardly see an individual "flake". Is that good?

So what ratio should I be looking for in mixing the paint?
 

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It sounds like you got lucky Robert, and may have found a suitable silver paint. Cool! :T

Yes, a small silver flake is what we are after. If the flakes are too large they will "wink" at you from the screen. :) Under PJ illumination they can look like very small extremely bright lights and are very distracting.

Now the test will be to put some in a white paint and see what the result is.

When I made the 2:1 mix (2 parts white paint:1 part CSMS) I was actually doing testing to find a darker screen paint than Black Widow when the thought struck we to see how light in shade I could go; C&S is the result.

I would try using a 2:1 mix (white:silver) and see what you get.

It sounds like house paint may be relatively inexpensive where you are. If so, besides the white paint, you might try a NCS color called "S 0502-R". This is actually a warm white; the idea is for the added warmth to off-set the bluish "push" that most silver paints have. Be sure to use flat or matte paints. There is a possibility that slightly glossier paints might work (the next step up from flat in the U.S. is called eggshell); but if the paint is too glossy a large screen made of it will "hotspot" (the center of the screen will look brighter than the corners).

I got the color "S 0502-R" by using the EasyRGB database and searching on the RGB colors 243 238 234. I think the NCS colors are available in your area. http://www.easyrgb.com/index.php?X=TINT

When I test mixes like this I use a 1/4 or 1/2 teaspoon measure to add the paint to a 2 ounce plastic disposable cup and then mix it with a "craft stick" (we also call them popsicle sticks), and then after it is mixed well by hand I spread a layer on a piece of white cardboard or heavy white paper, trying to get as smooth a surface as I can.

While you might not be able to see any reflective particles in the wet paint, you should see some in the dried sample.

If you would like me to measure any samples of your experiments with my spectrophotometer, just PM me for my address.
 

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robert - what is the name of the silver paint you have bought?
maybe i can pick it up in the UK aswell.

finding a silver paint for the UK equivalent to what is used in C&S is on my to do list. so i'm hoping you have saved myself a search :bigsmile:
 

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Hi Robert,

I don't know why I didn't think of this before! :duh:

If you will PM your address to me I will send you samples of CSMS and C&S so you can compare them to what you have.

I'll get some to you too Custy. :T
 

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Discussion Starter #16
Custy, Don you are too kind both of you.

I started to investigate what kind of paint I actually bought, only to find this.....sorry to say this..but...:wits-end:moron:wits-end: on the other end of the telephone line. But my fire was lit, so I kept on digging.

With an probability of 99% I can say that the paint is produced by http://www.pebeo.com. The positive thing is that they sell all over europe (including UK), the negative is that I have yet to find out exactly what color it is. The local art shop in Sweden has relabeled the bottles and absolutely refuse to tell me the OEM name.

Nevertheless, I did a quick&dirty and mixed OTS White wall paint (I had some left over in the basement) with the silver. My daughter had to give up her hair dryer so I could do important stuff...like drying paint with it :heehee:. Although it is a very small area I painted on some left over masonite I must say that after it dried up...I sort of...WTF?..wait a minute..:time-out:..

It very light grey, yes, but with light on it shines up. Up on the white wall and the DVE-disc in the player I now understand what you mean. The black gets "blacker", and the effect of the blackness is greater if I allow some stray light into the cinema room. But as a "no-auto-iris" puritan the black effect is visible even under my "optimum" conditions. The white? Well, yes the white is of course not as white as the white wall. The laws of physics is still there. BUT, I do understand that If you have BOTH white and black on the C&S the white SEEMS very bright because your black is so...black.

This is only after painting a very small sample.

Ok, down to earth again. The silver paint I bought is called "acrylic semi-gloss". During the small test yesterday I could absolutely say that the mix I got is too shiny for me. So the base to buy should be very flat. In Sweden we grade the gloss in numbers. 90 is high gloss for door frames etc. 20-30 gloss if for bathroom paint. 5-7 is wall paint and 1-3 is ceiling paint. So if the silver is like 20’ish we might have a problem. But I shall mix it with superflat white.

Also there is one more large supplier I shall visit today. Maybe they are more cooperative.

Once I’ve made a few samples, I’d love to send them to you for spectral analysis.

I am going to start a new thread as we now are OT in relation to my original question…
 

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thanks harp for the offer of the samples. they will certainly help me with finding a suitable silver paint.

robert - the pebeo paints are definitely available in the uk. i have some of their colors already which i use for correcting color pushes.
when i had a look at their silvers a few moons ago i seem to remember an irridescent silver. sounds like you have a different version.

the pebeo paints are available in USA aswell
 
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