Testing ALR Projector Screen paint - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 2 Old 06-09-19, 10:05 AM Thread Starter
Shackster
 
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Join Date: Jun 2019
Location: Barcelona, Spain
Posts: 7
Testing ALR Projector Screen paint

Hi all

Thank you for contributing to the forum. I've found very useful information here!

After some time reading the threads and learning, I decided to share my experiences. Any comments are very appreciated.

I use a projector for watching the TV and movies at home, in a non-dedicate room with ambient light. Two months ago, I was going to watch the TV at midday, and I realized that was very tedious to close all the windows of the room each time I wanted to use the projector. So, I decided to start looking how can I improve that. After considering several options, I decided to buy a new brightness projector, the Epson EB-2042 with 4400 lumens. The difference with the previous one was impressive, mainly by the fact that the new projector uses the 3LCD technology and provides more brightness. So I was very happy with the change.

I have the projector at 4.7m from the projection wall with a 120" diagonal size. The estimated image brightness computed at projectorcentral website is 75 fL for a projector screen with gain 1.0. In ECO Mode, the image brightness is reduced by 50%.

However, after some days I started wondering if that could be improved. I started thinking on having a non-expensive ALR projector screen, so I started looking at the different options: buy a cheap one, buy the material or paint the wall. After looking at the different manufacturers, I realized these are too expensive, so I started trying the other two options.

Test protocol
To compare the different screens, I made the following rudimentary tests:
1. Dark Room test: Test white and black colors at the center of the screen in a dark room (windows closed)
2. Ambient Light Room test: Test white and black colors at the center of the screen in an ambient light room
3. Spotlight Dark Room test: Test white color in a dark room (windows closed) at the four corners of the projector screen: bottom left, top left, top right and bottom right.

The test consists of projecting an image with black or white colors, capture an image with my mobile using manual fixed settings and measure the luminance of the white and black colors in the image using the Windows Paint.

Testing screen materials samples
I ordered the following projector screen materials samples: MaxWhite, ProWhite and ProGray from PSM and CineGrey3D and CineGrey 5D from Elite Screens.

After testing the materials, the results were very interesting. The PSM materials does not have angular reflective properties, while the Elite Screens materials do. The Elite Screens materials have better blacks and better ALR. However, the hotspot effect is very high, specially for the CineGrey 3D at the top left corner. So I decided to start testing the screen paints.

Testing screen paints
I bought some of the recommended paints that I found in this forum and AVS forum and started testing. I live in Spain, so I can only test the paints that are available here. These are the mixes I tried:
1. FolkArt 1:1: 50% FolkArt Gunmetal Gray + 50% FolkArt Medium Gray
2. FolkArt 1:2: 75% FolkArt Gunmetal Gray + 25% FolkArt Medium Gray + a bit of water + a bit of white plastic paint
3. AAA + Plastic Paint: 20% AutoAir Metallic Fine + 80% White Plastic Mate Paint + some drops of black tint
4. AAA + FolkArt Grey: 50% AutoAir Metallic Fine + 50% FolkArt Medium Gray

As you can see, I could not find the Dulux paint locally. So I made the mixes using FolkArt Medium Gray or a standard White Plastic Mate paint.

After testing the screen paint mixes, I realized that the angular reflective properties provided by the metallic paints are less than the provided by the screen materials tested before. This is good news for me, since I got too much hotspot using the tested ALR materials. Another conclusion is that when using the white plastic paint (mix 2 and 3), the effects of the metallic paint disappear. However, for the mixes 1 and 4, the metallic paint provides good reflective properties for rejecting ambient light.

In the next days I will try to understand why the standard white mate plastic paint is not working with metallic paints and try other paints for mixing with the metallic ones. I would also like to try mixing metallic FolkArt with matte water-based poly (as the original FolkArt mix) despite it is not recommended for rolling.

Images
Find attached some images and graphs showing the results of the different tests.
* ScreenMaterials_ALR: Image shows the 5 tested screen materials from left to right: MaxWhite, ProWhite and ProGray from PSM and CineGrey3D and CineGrey 5D from Elite Screens. The projector is shown an image divided in white (up) and black (down).
* ScreenMaterials_DarkRoom: The same materials in a dark room
* PaintMixes_ALR: Testing the paint mixes from left to right (1, 2, 3 and 4) in ambient light room
* PaintMixes_DarkRoom: Testing paint mixes in dark room
* ALRoom: Graphic showing the results on Ambient Light Room. The screens with angular reflective properties have better blacks.
* DarkRoom: Graphic showing the results on Dark Room
* DarkRoomHotspot: Graphic showing the results of Hotspot. CineGrey 3D have a high hotspot at top left corner.



Paint references
* White Plastic Mate: https://www.pinturas-alp.com/producto/apolo-formula/
* FolkArt Gunmetal Gray: https://plaidonline.com/products/fol...etal-gray-2-oz
* FolkArt Medium Gray: https://plaidonline.com/products/fol...dium-gray-8-oz
* AutoAir Aluminium Base Fine: https://autoaircolors.com/custom-aut...aint/4101.html
Attached Thumbnails
Testing ALR Projector Screen paint-screenmaterials_alr.jpg  

Testing ALR Projector Screen paint-screenmaterials_darkroom.jpg  

Testing ALR Projector Screen paint-paintmixes_alr.jpg  

Testing ALR Projector Screen paint-paintmixes_darkroom.jpg  

Testing ALR Projector Screen paint-darkroomhotspot.png  

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Last edited by xplanes; 06-09-19 at 03:48 PM.
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post #2 of 2 Old Today, 06:32 AM Thread Starter
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Join Date: Jun 2019
Location: Barcelona, Spain
Posts: 7
Re: Testing ALR Projector Screen paint

Hi again!

I've been doing some more tests using a paint from a local manufacturer called Vallejo. They have acrylic paints at low price and the results of the testing was very good. For the first mix "Vallejo Silver", I used Grey and Silver paints. For the second mix "Vallejo Dark", I've added some dark to the mix. I liked the results of this second mix, so I decided to paint the wall.

The final mix "Vallejo Dark" (22):
- 500 ml Vallejo Gris Medio (7)
- 500 ml Vallejo Plata (10)
- 200 ml Vallejo Negro (5)
- 500 ml Water (I added more water for the second hand)

I did two hands using a short nap roller for a projector screen of 5m2 aprox. and still there is some paint mix remaining.

Pros:
- Blacks are much better
- Ambient Light rejection works fine

Cons:
- Acrylic paint is very thick. Maybe more water would be better for painting more smoothly
- The wall has some irregularities and this affects the projected image when projecting white colors
- I can see some brightness irregularities caused by the metallic paint in some zones. Maybe I should mix it better next time
- The whites have too much metallic. Maybe adding less metallic would be better, but this will affect the ALR...

I'm thinking on building my own projector screen this summer and paint it using this mix, just to get rid of the irregularities of the wall and testing the mix with less metallic...

Any comments are much appreciated!
Xavi

Attachments:
- ALRoom2.png: Results in a room with ambient light
- DarkRoom2.png: Results in a dark room
- DarkRoomHotspot2.png: Hotspot in dark room
- IMG_20190619_201622_875.jpg: Paint pots
- IMG_20190623_105839_154.jpg: Paint mix
- IMG_20190623_152028_740.jpg: Painted wall
- IMG_20190624_090150_096.jpg: Zoom into the painted wall
- IMG_20190624_094215_333.jpg: A white image projected in a dark room. You can see the irregularities of the wall, irregularities of the paint mix and the silver effect of the metallic paint
- IMG_20190624_115244_264.jpg: Sample image with some ambient light
- IMG_20190624_104623_193.jpg: Sample image with a lot of ambient light
Attached Thumbnails
Testing ALR Projector Screen paint-darkroomhotspot2.png  

Testing ALR Projector Screen paint-img_20190619_201622_875.jpg  

Testing ALR Projector Screen paint-img_20190623_105839_154.jpg  

Testing ALR Projector Screen paint-img_20190623_152028_740.jpg  

Testing ALR Projector Screen paint-img_20190624_090150_096.jpg  

Testing ALR Projector Screen paint-img_20190624_094215_333.jpg  

Testing ALR Projector Screen paint-img_20190624_115244_264.jpg  

Testing ALR Projector Screen paint-img_20190624_104623_193.jpg  

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