I titled this post A Simple Screen Paint Solution first because I hope it is just that and secondly years from now someone might search on some of those words and it will lead them to this post.
I don't intend this thread to be the definitive answer to a DIY screen that will solve every possible ambient lighting and projector issues from this day forward. Nor do I claim if you follow these directions your screen will out produce the best DIY and commercial screens hands down. Rather this thread is intended for the novice coming here looking for a fairly easy straight forward approach they can use to get up and running with results so good that the vast majority will be content to sit back and watch movies and not worry about gaining any more improvement. There are 10's of thousands of posts here on this topic and this one is prefixed with IMHO to all that follows.
Before you read more I want to acknowledge two other old threads on the topic started by member Tom_bombadil they are:
http://archive.avsforum.com/avs-vb/s...hreadid=344875
http://archive.avsforum.com/avs-vb/s...hreadid=418361
I feel he was sincere in his efforts regarding a paint solution based around a range of paint colors he refers to as neutral grays. He did a good job of explaining the function of just black as a pigment added to base of just white in small quantities to make varying shades of gray.
The theory goes something like this. With any projector in any room one would think white would be the best color to make a screen after all pure white absorbs none of the colors and reflects them all. Black would be the worst as it would absorb all the colors and reflect none. And any other color red blue green etc would try and reflect more of that color and would give the image a Push in that direction. So why gray? Blacks / darks are the most difficult to project because they are projecting nothingness or close to it. They are achieved by not lighting up the screen and rely on what we see the screen as when no light is on it. In a totally dark room a white screen is going to look black but what happens when we have an image of a person skiing down a mountain in a black coat. All that white lights the room up all the objects in the room light up from the reflected snow and re-reflect back at the screen washing out the black and showing us some of the color of the screen in that area. By going gray we trick our eye into seeing a little less lightness in the black. Our eye and brain also has a way of seeing the brighter reflected light off the gray as white. So in actuality our brain interprets the image to have a greater contrast. Blacks look blacker and whites don't seem to be affected enough to not see them as whites still. This is not conjecture on my part it is very evident after doing some very simple comparisons. Keep in mind the shade of gray he's talking about start at very slight and go up to not even a med gray. Also keep in mind there are 3 key factors that will dictate what gray will give you improvement. They are projector, screen size, and the room you are in. This explanation may not have all the light science associated with it that it could but once again it's my attempt at a simplified explanation of what takes place when projecting to a gray screen vs. white.
Everyone new to DIY needs a starting point to benchmark against. And I have seen so many seeking a path to follow in getting a good first DIY screen. (Myself included a short time ago.) I want to both document my learning curve here as my information is scattered throughout the threads and document others efforts and results.
My hope for this thread is two fold first I don't have the magic formula that will allow you to plug in the three items listed above and out will come a formula for a gray paint. What I'm hoping is others that use neutral gray and neutral gray only come here and post their data. Here is how I would like it to be listed along with the combination of white base of the matte finish the amount of black that was added to it, then the projector model and the lumens it produces, also the screen size and the material its painted over. And any other information you want to add about special conditions in the room etc. This information would be of great help to a newbie coming here to get a starting point to go from. I am also sure there is someone out there that for whatever reason all there factors line up to this. Just plain white is as good as it gets. If that's your case that's a good input also. Some of the old pros here with 100's of experiments and dozens of screens to their credit my want to take the information to a higher level. I would love to see someone make a stab at compiling a list relating ether projector models / screen size or lumens / screen size or even ft-L each to a range of Gray mixes. So that's a challenge to anyone a lot wiser and more experienced than me if they would like to take it up.
The second reason for this thread is I hope to expand to the next level of this gray paint idea and I have done this and proved to myself it works. And that is a topcoat over the gray. With help from the members here I was encouraged to try and once I found the proper shade of neutral gray for my projector thru experimentation (trial and error). I was 95% satisfied with my screen. but thought I could add that final touch.
The Topcoat:
It's a mixture of the same latex neutral gray paint I found to be best mixed with a clear water based polyurethane. They combine together and become a new paint with the same color or very close to it as the original, but the addition of the polyurethane raises the gain of the screen. This like the addition of the black pigment is selective to the same 3 qualifiers projector, screen size and room. The mixture rates could range from zero poly to paint to pure poly over paint. But from what I have found the real world ranges would be this. First no poly just like some projector may work best on a matte white screen others may be perfect with just the adjusted matte gray.
Some others would be poly : paint. listed in order of mild to wild . .5:1, 1:1 1.5:1, 2:1. 2.5:1 as you can see the greater the proportion of poly to paint the more gain you could hope to get.
A good read on this is here.
http://www.avsforum.com/avs-vb/showthread.php?t=655720
So to summarize to this point. The process is this in a nut shell. All things start with matte white we then sneak up the gray scale a little at a time until we reach a point based on our equipment and setup where we feel we have maximized the benefits of the neutral gray effect on improving the contrast we perceive and the black/ dark end of the image and begin to effect what we perceive as whites on the other end. And then maybe back down a hair. At that point you stop thinking gray and ask yourself would the image be improved by an increases in gain? If so you sneak up that path until you are comfortable with improvement and stopping short of getting into hot spotting issues.
If the experimentation method is used to get where you want to be you will have done this as I did. Hopefully we might with a little effort be able to build a database here that someone could just follow and reproduce a nice workable screen without doing the testing. If you are like me and want to test this to death and feel you have maximized everything in the end I would make the following suggestions.
Build a test screen first not huge but large enough to see a good area of your image 3x3 foot maybe make it of the same material you will be painting on and view it against some kind of standard backing for comparison. I used a large piece of BOC. When you get close split the test screen in half so you can do side by side comparisons do this also with the top coat if you feel you want the gain boost. Make sure to set your test screen in different locations of your full screen also. hot spotting might not show to the sides etc.
Here is my information copied from the above post as a first data point.
So here is my final specs on the system if anyone wants to know for comparison to something they may want to do.
Projector Sharp XR10X mounted 14.5 feet running in eco mode with all settings set to zero projecting to a canvas screen 72x96 painted with the following.
Paint from Lowes American Traditions / base is the lowest luster matte finish. The paint spec is Silver Leaf 4006-1A I had them read back to me the paint mix and it consisted of black and raw umber as the only tints. I had them add the black and the substitute black for the raw umber so that the only pigment in the paint was black. The screen was painted with 3 coats of the paint. Over 3 days no sanding. Then it was given one coat of the same paint mixed 50-50 with water based polyurethane the brand I used was Olympic.
This process lead to great results with the sharp 2000 lumen DLP projector
I hope more information from other members follow. And I hope this is of some help to the newbie's of the world even if they don't choose to go this route. As projectors evolve the demands of the screen are greatly lessened. I personally am now very content with viewing what's considered by today's strands a very low end projector, projecting to a very low tech screen.
------------------------------------------------------------------------------
Edit 10/12/06 Things I have learned along the way.
------------------------------------------------------------------------------
I came here about a year ago and lurked a few months trying to sort a few morsels out of a sea of ideas. I began experimenting and began posting both my thoughts and my questions and later my experiment results. Then there came a point I felt I had gained some minimum knowledge and enough to try and write one post that started at a point and went to a conclusion. (Something that seldom happens at AVS DIY) I didn't have a level of understanding I have now but I did have a near perfect screen for my application and thought why not share what I had done to date.
That's the above post.
I still stand by 99% of what I wrote into that post. But I do have new understandings of the whole Neutral gray method and thought I would add them now.
First off neutral gray does everything I claimed it would but it does it at some cost. This cost is efficiency. When light (any color) strikes a screen surface that is neutral it is partly reflected and partly absorbed. The white pigment reflects mostly all the colors it receives and the black pigment absorbs mostly all. That percent that is black causes losses and without ample lumens of projected light those losses can result in loss of picture quality (PQ). The lost PQ is not in the form of colors or even white for that matter it's in the form of brightness. What I had hoped the poly would do was adjust the sheen level enough to boost the screen gain that nothing would be lost.
In my case starting with a very bright projector that was a non issue. I failed to realize at that time the gain improvement from sheen was limited and there was a large group of projectors that were underpowered to totally approach there screen design using this method. Not so much they were underpowered but rather people were pushing their screen sizes into the low Foot Lambert (FL) ranges.
Any screen that has to be in the 1 plus range and is subjected to ambient light issues will benefit from neutral gray, but you might not be able to get the FL back up to where they need to be with poly alone. There has been some great efforts put forth here this year in finding methods and materials that will enhance gain along with poly for those people that are starting out with not enough FL for the screen size they want to build. These additives are the metallic. They do work and will work in conjunction with the neutral gray methodology spelled out above. Some of the later posts in this thread show some of these ideas, and I wanted to point them out in the opening post.
On a good note the trend in projectors as of late are more lumens it seems. And as these higher-powered units become more mainstream higher gain requirements will lessen.
-----------------------------------------------------------------------------------------------
Edit 10/16/06
The best thread that compares neutral gray screens made with poly and those made with poly and metallic to date is the Thread member Tiddler started titled
RS-MaxxMudd Experiments see link below
http://www.avsforum.com/avs-vb/showthread.php?t=713810
This thread not only shows comparative screen shots that allow the viewer to see what improvements could be had with use of metallic's in terms of additional gain improvement. It's also a great example of how screen shots should be taken when comparing samples. The use of on and off axis shots and also dark and ambient room lighting clearly show what's happening with the screen when metallic is added. Keep in mind the projector used with these comparisons is of lower lumen output than the one I used in the below screen shots.
Click thumbnail to be taken to my neutral gray screen shots page. Once there you can navigate thru photos with explanations.
-----------------------------------------------------
Edited 12-11-06
Although my screen made with only lamp black added to white base paint gave me both an appealing gray color to the eye and flawless performance with my DPL projector. It's the belief of many and their own testing with their projectors lead them to find a color push when the simple formula above was put into effect. Most talk of a blue push.
The reason for this has not yet been explained and could lie in several areas. But testing of lamp black only grays on a spectroscope show the paints favoring blue in a very slight way. It could be a by-product of the vast number of white or not so white bases being used.
In the latest posts to this thread, understanding this push and then finding a correction to it is the current topic. There is still a desire by me to tweak if necessary the lamp black gray. And these tweaks would add no cost to the paint as they are readily available pigments when the paint is mixed. The percent is very small and the pigments are in the yellow, gold and umber side of the color wheel.
We have yet to find the right pigments and ratios but anyone wanting to reach maximum neutral gray may want to skip down to that area and learn more.
-----------------------------------------------------------------------------
Edit Feb 20, 2007
-----------------------------------------------------------------------------
Thanks to member Tiddler I believe the best pigment component to add in addition to lampblack is yellow oxide.
His thread outlining this is:
http://www.avsforum.com/avs-vb/showt...1&page=1&pp=30
The testing that has been done to measure the Red Green Blue or RGB color values of the gray paints made with lampblack have shown that the addition of some yellow oxide pigment brings the RGB numbers closer to neutral or all the same.
Keep in mind doing this wont change the cost of going to the paint store and buying a gallon of wall paint. The yellow oxide like the lampblack are pigments that are in all commercial paint mixing machines and are closely controlled when dispensing.
The rate of yellow oxide required is in the range of half or less the amount of lampblack. For example if you determined you needed 16oz of lampblack to a gallon of white base then you could also add 8oz of yellow oxide.
The benefits of being neutral are apparent but in my case I still haven't found the need for the addition of yellow oxide to the screen I'm currently using. My projector had more than enough calibration range to compensate for the cooler shade of neutral gray.
I don't want to get into the complex discussion of color science and color temp. because this thread is intended to remain simple. But the short version is this. a neutral gray made with white and lampblack only is neutral around the color temp 7500k while the neutral gray made from white, lampblack and yellow oxide as talked about above is neutral at a color temp of 6500k. Most projectors allow you to select a color temp to run at in the menu and I have mine set to 7500k.
So if you are a purest at heart and want to be set to the industry standard of 6500k then I want to provide this information and links to the threads that are currently experimenting along these lines in the opening post here.
One side note and of only slight consequence to your viewing pleasure is the outward appearance of the two neutral grays. A 6500k neutral gray is not a very pretty shade of gray by many accounts. It's a dirty looking gray tone. The lampblack only or 7500k neutral gray is a much more appealing gray to view when the lights are on and the projector is off. Some people building fixed screens and using them in living room settings may want to consider this. 48 square feet of screen as I have does make an imposing fashion statement. I have also proposed for people wanting to go stealth with the screen, and paint out the whole wall as a accent wall might find the 6500k gray hard to take.
One place the above linked thread and this one diverge is in the use of poly as a top coating for gain improvement. Both methods hold promise I believe. The above listed method uses pure poly of the lowest luster available and it adds a degree of sheen to the surface improving whites while holding blacks dark.
That is the same results I found by using a higher luster poly but mixing it down in the paint that had been selected as right for the application. I still feel blending the poly with the paint avails one to the greatest amount of range of sheens with the least amount of purchases. And I still would recommend doing the basecoat of just the latex neutral gray first as it will save the quantity of poly required.
----------------------------------------------------------------------------------------------
Edit July 2, 2007
----------------------------------------------------------------------------------------------
Below are 8 tint formulas based around making 1 quart of screen paint that will be close to neutral gray. These formulas can be taken to any paint store and they will understand what is required as long as you tell them (one quart) (pure white base) (flattest sheen base, matte or flat) the Easy-01 is the lightest shade of gray the 08 the darkest. This range should cover most needs based around screen size and projector lumens as described above. If a gallon of paint is required simply multiply the pigments by 4.
As described above these paints can be used alone or in combination with poly. The poly will add a degree of sheen to the painted surface and increase gain a slight amount. As described above the poly can be blended with the paint or if an extremely flat finish poly such as Behr Water Based Polyurethane No. 780 it can be directly used as a top coat alone. Both methods have shown great results.
Easy-01
0 1 0 Lamp Black
0 0 1 Yellow Oxide
Easy-02
0 2 0 Lamp Black
0 0 1 Yellow Oxide
Easy-03
0 3 0 Lamp Black
0 1 0 Yellow Oxide
Easy-04
0 4 0 Lamp Black
0 1 1 Yellow Oxide
Easy-05
0 5 0 Lamp Black
0 2 0 Yellow Oxide
Easy-06
0 6 0 Lamp Black
0 2 1 Yellow Oxide
Easy-07
0 7 0 Lamp Black
0 2 1 Yellow Oxide
Easy-08
0 8 0 Lamp Black
0 3 0 Yellow Oxide
The above tint formulas and the solution of top
coating the flat latex near neutral grey base, came to me by a
former member who developed these solution. Of utmost importance to this
former member was the sharing of the information with the forum. so i have reposted it here.
As a point of reference my very bright 2000 lumen business projector doing a 72x96 screen would be an Easy-06. At that level of gray it performs great as both a lights out movie screen and a moderately ambient lit room for things like sports viewing. Photo documentation of that is shown in the threads linked in my signature below each post.
I don't intend this thread to be the definitive answer to a DIY screen that will solve every possible ambient lighting and projector issues from this day forward. Nor do I claim if you follow these directions your screen will out produce the best DIY and commercial screens hands down. Rather this thread is intended for the novice coming here looking for a fairly easy straight forward approach they can use to get up and running with results so good that the vast majority will be content to sit back and watch movies and not worry about gaining any more improvement. There are 10's of thousands of posts here on this topic and this one is prefixed with IMHO to all that follows.
Before you read more I want to acknowledge two other old threads on the topic started by member Tom_bombadil they are:
http://archive.avsforum.com/avs-vb/s...hreadid=344875
http://archive.avsforum.com/avs-vb/s...hreadid=418361
I feel he was sincere in his efforts regarding a paint solution based around a range of paint colors he refers to as neutral grays. He did a good job of explaining the function of just black as a pigment added to base of just white in small quantities to make varying shades of gray.
The theory goes something like this. With any projector in any room one would think white would be the best color to make a screen after all pure white absorbs none of the colors and reflects them all. Black would be the worst as it would absorb all the colors and reflect none. And any other color red blue green etc would try and reflect more of that color and would give the image a Push in that direction. So why gray? Blacks / darks are the most difficult to project because they are projecting nothingness or close to it. They are achieved by not lighting up the screen and rely on what we see the screen as when no light is on it. In a totally dark room a white screen is going to look black but what happens when we have an image of a person skiing down a mountain in a black coat. All that white lights the room up all the objects in the room light up from the reflected snow and re-reflect back at the screen washing out the black and showing us some of the color of the screen in that area. By going gray we trick our eye into seeing a little less lightness in the black. Our eye and brain also has a way of seeing the brighter reflected light off the gray as white. So in actuality our brain interprets the image to have a greater contrast. Blacks look blacker and whites don't seem to be affected enough to not see them as whites still. This is not conjecture on my part it is very evident after doing some very simple comparisons. Keep in mind the shade of gray he's talking about start at very slight and go up to not even a med gray. Also keep in mind there are 3 key factors that will dictate what gray will give you improvement. They are projector, screen size, and the room you are in. This explanation may not have all the light science associated with it that it could but once again it's my attempt at a simplified explanation of what takes place when projecting to a gray screen vs. white.
Everyone new to DIY needs a starting point to benchmark against. And I have seen so many seeking a path to follow in getting a good first DIY screen. (Myself included a short time ago.) I want to both document my learning curve here as my information is scattered throughout the threads and document others efforts and results.
My hope for this thread is two fold first I don't have the magic formula that will allow you to plug in the three items listed above and out will come a formula for a gray paint. What I'm hoping is others that use neutral gray and neutral gray only come here and post their data. Here is how I would like it to be listed along with the combination of white base of the matte finish the amount of black that was added to it, then the projector model and the lumens it produces, also the screen size and the material its painted over. And any other information you want to add about special conditions in the room etc. This information would be of great help to a newbie coming here to get a starting point to go from. I am also sure there is someone out there that for whatever reason all there factors line up to this. Just plain white is as good as it gets. If that's your case that's a good input also. Some of the old pros here with 100's of experiments and dozens of screens to their credit my want to take the information to a higher level. I would love to see someone make a stab at compiling a list relating ether projector models / screen size or lumens / screen size or even ft-L each to a range of Gray mixes. So that's a challenge to anyone a lot wiser and more experienced than me if they would like to take it up.
The second reason for this thread is I hope to expand to the next level of this gray paint idea and I have done this and proved to myself it works. And that is a topcoat over the gray. With help from the members here I was encouraged to try and once I found the proper shade of neutral gray for my projector thru experimentation (trial and error). I was 95% satisfied with my screen. but thought I could add that final touch.
The Topcoat:
It's a mixture of the same latex neutral gray paint I found to be best mixed with a clear water based polyurethane. They combine together and become a new paint with the same color or very close to it as the original, but the addition of the polyurethane raises the gain of the screen. This like the addition of the black pigment is selective to the same 3 qualifiers projector, screen size and room. The mixture rates could range from zero poly to paint to pure poly over paint. But from what I have found the real world ranges would be this. First no poly just like some projector may work best on a matte white screen others may be perfect with just the adjusted matte gray.
Some others would be poly : paint. listed in order of mild to wild . .5:1, 1:1 1.5:1, 2:1. 2.5:1 as you can see the greater the proportion of poly to paint the more gain you could hope to get.
A good read on this is here.
http://www.avsforum.com/avs-vb/showthread.php?t=655720
So to summarize to this point. The process is this in a nut shell. All things start with matte white we then sneak up the gray scale a little at a time until we reach a point based on our equipment and setup where we feel we have maximized the benefits of the neutral gray effect on improving the contrast we perceive and the black/ dark end of the image and begin to effect what we perceive as whites on the other end. And then maybe back down a hair. At that point you stop thinking gray and ask yourself would the image be improved by an increases in gain? If so you sneak up that path until you are comfortable with improvement and stopping short of getting into hot spotting issues.
If the experimentation method is used to get where you want to be you will have done this as I did. Hopefully we might with a little effort be able to build a database here that someone could just follow and reproduce a nice workable screen without doing the testing. If you are like me and want to test this to death and feel you have maximized everything in the end I would make the following suggestions.
Build a test screen first not huge but large enough to see a good area of your image 3x3 foot maybe make it of the same material you will be painting on and view it against some kind of standard backing for comparison. I used a large piece of BOC. When you get close split the test screen in half so you can do side by side comparisons do this also with the top coat if you feel you want the gain boost. Make sure to set your test screen in different locations of your full screen also. hot spotting might not show to the sides etc.
Here is my information copied from the above post as a first data point.
So here is my final specs on the system if anyone wants to know for comparison to something they may want to do.
Projector Sharp XR10X mounted 14.5 feet running in eco mode with all settings set to zero projecting to a canvas screen 72x96 painted with the following.
Paint from Lowes American Traditions / base is the lowest luster matte finish. The paint spec is Silver Leaf 4006-1A I had them read back to me the paint mix and it consisted of black and raw umber as the only tints. I had them add the black and the substitute black for the raw umber so that the only pigment in the paint was black. The screen was painted with 3 coats of the paint. Over 3 days no sanding. Then it was given one coat of the same paint mixed 50-50 with water based polyurethane the brand I used was Olympic.
This process lead to great results with the sharp 2000 lumen DLP projector
I hope more information from other members follow. And I hope this is of some help to the newbie's of the world even if they don't choose to go this route. As projectors evolve the demands of the screen are greatly lessened. I personally am now very content with viewing what's considered by today's strands a very low end projector, projecting to a very low tech screen.
------------------------------------------------------------------------------
Edit 10/12/06 Things I have learned along the way.
------------------------------------------------------------------------------
I came here about a year ago and lurked a few months trying to sort a few morsels out of a sea of ideas. I began experimenting and began posting both my thoughts and my questions and later my experiment results. Then there came a point I felt I had gained some minimum knowledge and enough to try and write one post that started at a point and went to a conclusion. (Something that seldom happens at AVS DIY) I didn't have a level of understanding I have now but I did have a near perfect screen for my application and thought why not share what I had done to date.
That's the above post.
I still stand by 99% of what I wrote into that post. But I do have new understandings of the whole Neutral gray method and thought I would add them now.
First off neutral gray does everything I claimed it would but it does it at some cost. This cost is efficiency. When light (any color) strikes a screen surface that is neutral it is partly reflected and partly absorbed. The white pigment reflects mostly all the colors it receives and the black pigment absorbs mostly all. That percent that is black causes losses and without ample lumens of projected light those losses can result in loss of picture quality (PQ). The lost PQ is not in the form of colors or even white for that matter it's in the form of brightness. What I had hoped the poly would do was adjust the sheen level enough to boost the screen gain that nothing would be lost.
In my case starting with a very bright projector that was a non issue. I failed to realize at that time the gain improvement from sheen was limited and there was a large group of projectors that were underpowered to totally approach there screen design using this method. Not so much they were underpowered but rather people were pushing their screen sizes into the low Foot Lambert (FL) ranges.
Any screen that has to be in the 1 plus range and is subjected to ambient light issues will benefit from neutral gray, but you might not be able to get the FL back up to where they need to be with poly alone. There has been some great efforts put forth here this year in finding methods and materials that will enhance gain along with poly for those people that are starting out with not enough FL for the screen size they want to build. These additives are the metallic. They do work and will work in conjunction with the neutral gray methodology spelled out above. Some of the later posts in this thread show some of these ideas, and I wanted to point them out in the opening post.
On a good note the trend in projectors as of late are more lumens it seems. And as these higher-powered units become more mainstream higher gain requirements will lessen.
-----------------------------------------------------------------------------------------------
Edit 10/16/06
The best thread that compares neutral gray screens made with poly and those made with poly and metallic to date is the Thread member Tiddler started titled
RS-MaxxMudd Experiments see link below
http://www.avsforum.com/avs-vb/showthread.php?t=713810
This thread not only shows comparative screen shots that allow the viewer to see what improvements could be had with use of metallic's in terms of additional gain improvement. It's also a great example of how screen shots should be taken when comparing samples. The use of on and off axis shots and also dark and ambient room lighting clearly show what's happening with the screen when metallic is added. Keep in mind the projector used with these comparisons is of lower lumen output than the one I used in the below screen shots.
Click thumbnail to be taken to my neutral gray screen shots page. Once there you can navigate thru photos with explanations.
-----------------------------------------------------
Edited 12-11-06
Although my screen made with only lamp black added to white base paint gave me both an appealing gray color to the eye and flawless performance with my DPL projector. It's the belief of many and their own testing with their projectors lead them to find a color push when the simple formula above was put into effect. Most talk of a blue push.
The reason for this has not yet been explained and could lie in several areas. But testing of lamp black only grays on a spectroscope show the paints favoring blue in a very slight way. It could be a by-product of the vast number of white or not so white bases being used.
In the latest posts to this thread, understanding this push and then finding a correction to it is the current topic. There is still a desire by me to tweak if necessary the lamp black gray. And these tweaks would add no cost to the paint as they are readily available pigments when the paint is mixed. The percent is very small and the pigments are in the yellow, gold and umber side of the color wheel.
We have yet to find the right pigments and ratios but anyone wanting to reach maximum neutral gray may want to skip down to that area and learn more.
-----------------------------------------------------------------------------
Edit Feb 20, 2007
-----------------------------------------------------------------------------
Thanks to member Tiddler I believe the best pigment component to add in addition to lampblack is yellow oxide.
His thread outlining this is:
http://www.avsforum.com/avs-vb/showt...1&page=1&pp=30
The testing that has been done to measure the Red Green Blue or RGB color values of the gray paints made with lampblack have shown that the addition of some yellow oxide pigment brings the RGB numbers closer to neutral or all the same.
Keep in mind doing this wont change the cost of going to the paint store and buying a gallon of wall paint. The yellow oxide like the lampblack are pigments that are in all commercial paint mixing machines and are closely controlled when dispensing.
The rate of yellow oxide required is in the range of half or less the amount of lampblack. For example if you determined you needed 16oz of lampblack to a gallon of white base then you could also add 8oz of yellow oxide.
The benefits of being neutral are apparent but in my case I still haven't found the need for the addition of yellow oxide to the screen I'm currently using. My projector had more than enough calibration range to compensate for the cooler shade of neutral gray.
I don't want to get into the complex discussion of color science and color temp. because this thread is intended to remain simple. But the short version is this. a neutral gray made with white and lampblack only is neutral around the color temp 7500k while the neutral gray made from white, lampblack and yellow oxide as talked about above is neutral at a color temp of 6500k. Most projectors allow you to select a color temp to run at in the menu and I have mine set to 7500k.
So if you are a purest at heart and want to be set to the industry standard of 6500k then I want to provide this information and links to the threads that are currently experimenting along these lines in the opening post here.
One side note and of only slight consequence to your viewing pleasure is the outward appearance of the two neutral grays. A 6500k neutral gray is not a very pretty shade of gray by many accounts. It's a dirty looking gray tone. The lampblack only or 7500k neutral gray is a much more appealing gray to view when the lights are on and the projector is off. Some people building fixed screens and using them in living room settings may want to consider this. 48 square feet of screen as I have does make an imposing fashion statement. I have also proposed for people wanting to go stealth with the screen, and paint out the whole wall as a accent wall might find the 6500k gray hard to take.
One place the above linked thread and this one diverge is in the use of poly as a top coating for gain improvement. Both methods hold promise I believe. The above listed method uses pure poly of the lowest luster available and it adds a degree of sheen to the surface improving whites while holding blacks dark.
That is the same results I found by using a higher luster poly but mixing it down in the paint that had been selected as right for the application. I still feel blending the poly with the paint avails one to the greatest amount of range of sheens with the least amount of purchases. And I still would recommend doing the basecoat of just the latex neutral gray first as it will save the quantity of poly required.
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Edit July 2, 2007
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Below are 8 tint formulas based around making 1 quart of screen paint that will be close to neutral gray. These formulas can be taken to any paint store and they will understand what is required as long as you tell them (one quart) (pure white base) (flattest sheen base, matte or flat) the Easy-01 is the lightest shade of gray the 08 the darkest. This range should cover most needs based around screen size and projector lumens as described above. If a gallon of paint is required simply multiply the pigments by 4.
As described above these paints can be used alone or in combination with poly. The poly will add a degree of sheen to the painted surface and increase gain a slight amount. As described above the poly can be blended with the paint or if an extremely flat finish poly such as Behr Water Based Polyurethane No. 780 it can be directly used as a top coat alone. Both methods have shown great results.
Easy-01
0 1 0 Lamp Black
0 0 1 Yellow Oxide
Easy-02
0 2 0 Lamp Black
0 0 1 Yellow Oxide
Easy-03
0 3 0 Lamp Black
0 1 0 Yellow Oxide
Easy-04
0 4 0 Lamp Black
0 1 1 Yellow Oxide
Easy-05
0 5 0 Lamp Black
0 2 0 Yellow Oxide
Easy-06
0 6 0 Lamp Black
0 2 1 Yellow Oxide
Easy-07
0 7 0 Lamp Black
0 2 1 Yellow Oxide
Easy-08
0 8 0 Lamp Black
0 3 0 Yellow Oxide
The above tint formulas and the solution of top
coating the flat latex near neutral grey base, came to me by a
former member who developed these solution. Of utmost importance to this
former member was the sharing of the information with the forum. so i have reposted it here.
As a point of reference my very bright 2000 lumen business projector doing a 72x96 screen would be an Easy-06. At that level of gray it performs great as both a lights out movie screen and a moderately ambient lit room for things like sports viewing. Photo documentation of that is shown in the threads linked in my signature below each post.