or Connect
AVS › AVS Forum › Display Devices › Screens › DIY Screen Section › DIY black screen tests
New Posts  All Forums:Forum Nav:

DIY black screen tests - Page 5

post #121 of 344
Thread Starter 
Quote:
Originally Posted by joikd View Post

New Design, is this the kind of stuff you are talking about?

http://www.chameleonfilm2u.com/index.php/products/residential-series

Yes, I'm sure they would work for the tinted layer. I don't know how competitively they price their tinted films but there are tons of options out there. If you search for window tint on ebay, you will see hundreds of options. A google search for anywhere that sells window films or window tint will give you a similar number so don't go for any of the super expensive options which either have features that won't help in a screen or just cost more because of the brand. Wether you go with window tint or dark rear projection screen material, the color and level of light transmission is the most important thing you are looking for.

The place in the link seems to have limited options on this. 30% may be too light and 10% may be too dark. I would look for a 25% tint on ebay and get the least expensive option that comes in the size you need. If possible, get a smaller sample piece first to make sure it is right for your taste and projector. Also, remember to test all 3 layers together as the tint will look different under the diffuser and over the reflective layer.

How many lumens does your projector put out and how big is your screen?
post #122 of 344
Thread Starter 
I confess, there is something I like about the way glass bead screens give the image a little extra depth and pop. I know it is old technology and we have better ways of achieving a higher gain these days. Not that the newer and brighter projectors really need it...

On it's own, I don't see much need for white glass bead screens anymore. In combination with newer and better performing methods, it is a different story. A micro lens array, or layer of beads (depending if you are buying or selling), does more than just make white material retro reflective. On "optical rear projection screens", they are used to diffuse light. On some of the more expensive commercial front screens, they are also used in conjunction with a "dark ambient light absorbing layer".

I am a fan of incorporating the things I like from other designs into my new designs and glass beads are a good way of diffusing light as well as increasing brightness. For example, taking a piece of mylar and adding a layer of beads, turns a highly reflective but specular surface into a super bright screen surface. This is how it looks. The beads are attached using a thin layer of transparent adhesive which is sprayed on:


When projected on, the image looks super bright and with no hot spots:


Here's another:


Similarly, adding beads to the back of a mirror sheet which has a dark coating which wouldn't be reflective enough to give a watchable image on it's own:


With the beads, you get a bright image and a surface that is still smooth (as long as the beads are small enough):


Again with the back of a mirror and a layer of beads:


Now, going back to the black screen design, adding a layer under the diffuser gives the screen a slight lift in brightness which is most noticeable with lighter imagery like skin tones. I am in the process of creating a test surface to get some pics to show the effect.

The beads can even be used instead of the diffuser as the beads act as a diffuser themselves. It doesn't look as good and you lose some smoothness but it is an option for some trying to save money or who can't find a diffuser large enough for the 300 inch screen they want to build. With the diffuser, I plan on doing a little more testing to see if adding an additional lens layer offers an overall net benefit. DNP seem to use a layer of beads in a number of their premium priced screens so it is worth the testing. I was thinking that a thin layer of beads could be added to glass as a front hard coat that doesn't require the use of the significantly more expensive anti reflective glass. More to come on that.

At the very least, using the beads with metalized reflective layers , like mylar, o diffuse them, is an easy and inexpensive way of creating high gain screens. Seems like a no-brainer to me. It's just so easy!
post #123 of 344
It's not in keeping with what we aspire to in DIY Screens to present to suggest any method or application that is considered sub-standard or less that optimal out of the gate.

If indeed it was so easy...and desirable (ie: effective..) you can be certain there would be a popular Thread right on top of the list....continually.

Beaded screens have already been attempted, using several various sized beads on a variety of backings, and in no way have the results ever been more than a application that had as many drawbacks as advantages...if indeed more of the former. I gotta vote with PB as far as that application...it's a rehash of efforts long dismissed...and for all the right reasons.

Sheer volume of effort cannot replace effective results.

Stick to methods and materials that you know will deliver exemplary results....your more than capable, and your efforts are appreciated cool.gif
post #124 of 344
I'm not sure how much you dug around that site, but that wasn't just regular tint. It was photochromic tint, which sounded like the recent film you were posting about that lightens and darkens depending on ambient light.
post #125 of 344
I ordered some screen samples of the Black Diamond 1.4 gain and .8 gain. I currently have a cheap $100 108" 1.0 gain screen with an Epson 8700UB 1, 600 lumen projector. I'm not impressed with the Black Diamond screen samples I received. The off axis viewing is really poor.

I taped the samples to my existing screen. The 1.4 is on the left and the .8 is on the right. The first image below is straight on. The second image is about 45 degrees off-axis. The last one is also taken at about 45 degrees off-axis. These were taken in dynamic mode in high (normal) lamp mode with two lamps on behind me.



It looks fine when viewing straight on with the screen. When viewing even slightly off-axis the image darkens substantially and has a strong blue tint. Not exactly something I would want to use for watching sporting events with a large group of people in my living room which is why I even considered such a screen.
Edited by Sancho101 - 10/28/13 at 8:50pm
post #126 of 344
No way The Black Diamond screen is worth $3900 for a 115" screen. For that kind of money you could buy an Epson 5020 AND a Lumagen Video processor and hit any of the DIY screens--including just an OTS gray--with 2000 lumens and have a far better picture than 600 lumens hitting a BD screen. Or, for a bit more money get one of the new Epsons with over 4000 lumens.
post #127 of 344
i wouldn't get too caught up in making definitive conclusions with 6 or 8 inch samples in the way that you are testing them. especially when they are considerably darker in color than a white screen.

know this, your projector is calibrated for your white screen. and given the amount of ambient light your testing in... the color, contrast, and black levels of your white screen are... in a word... wrong.

so your now comparing an uncalibrated tiny dark sample to a whole white screen that has more than 50% less contrast and color saturation in ambient light.

in other words... comparing wrongly saturated to wrongly calibrated... and then making an un-informed decision. wink.gif
Edited by pb_maxxx - 10/28/13 at 9:53pm
post #128 of 344
of course... on the other hand... i also second what kirnak just posted.
post #129 of 344
I agree that my tests using their samples is less than scientific. I'm just making a comparison in ambient light the way Screen Innovations does in their promotional videos. They probably do calibrate to their screens in their videos. I just wanted to highlight the difference I was seeing in off-axis viewing vs. straight-on. I have never seen a Black Diamond screen in-person. Maybe my perceptions would be different if I were to see their screen full-size and calibrated.
post #130 of 344
i must be getting old. cause sometimes i re-read my posts and realize how harsh they sound. i hope i don't become one of the older, grumpy, talk to myself kinda bitter men. lol.

it's true answer lies somewhere in between. still, you're justified in knowing for yourself that your money could be spent more wisely and never wonder... what if i had a black diamond.
post #131 of 344
It's always been quite evident that SI loads their Demo examples in gross favor of the strong points of the BD and wholly avoids direct comparisons with even any basic High Contrast material...opting to only illustrate "Directly Viewed on Axis" examples comparing their product against a Matte White.

Hype notwithstanding, it's all simply marketing, and a misguided conception of how what they feel the "Majority" of Home Theater advocates are setting up their viewing situations. Overly promote it, and price it stratospherically...and there is always a gullible Buyer waiting in the wings.

Such screens have always depended upon..nay....counted on all viewing to be done directly on axis. In contrast (..oh the pun! ) most every DIY application that is designed to replicate or surpass the SI-BD has umpteenth better off-axis viewing, because none of them aspire to be so grossly Retro-reflective.

A telling anecdote: The DIY apps that did try to achieve such similar "on axis only" performance never made it far "out of the gate" with DIY'ers.
post #132 of 344
Thread Starter 
Quote:
Originally Posted by joikd View Post

I'm not sure how much you dug around that site, but that wasn't just regular tint. It was photochromic tint, which sounded like the recent film you were posting about that lightens and darkens depending on ambient light.

I will take another look. I must admit, I only skimmed it quickly because I was in a hurry at the time. The tint I was using that darkened as the light increased, was a rigid acrylic substrate from an optical glass manufacturer. It wasn't a window tint film. I have never tested any window film with those properties but I see no reason why it wouldn't work (as long as its darkest state doesn't doesn't cut light transmission too much).

If you test it and find it viable, I would be very interested to see some pics. Good find if the price isn't too high.
post #133 of 344
Thread Starter 
I am not one to jump in an defend BD. I just wanted to offer a suggestion on the test:


I can't see how bright the room is in the pics but judging by the washed out look of the white screen, I am assuming that you have at least some room lights on (which makes sense if you are testing the BD screen material). A point I would make on the viewing cone thing, is that you should test it again with the lights off too. On my black-screen, the retro reflective surface makes the viewing angle narrower in a super bright room. It is still fairly wide and certainly wide enough for any seat on my couch, but, with the curtains open on a sunny afternoon, there is a noticeable drop in brightness from the extreme side of the room. With the white screen, I can't see a watchable image, even from front and center, in that level of light. If I make the room dark enough to get a watchable image on both, the black screen is bright enough to watch from the sides without any issues. It is also watchable from the sides with room lights on in the evening.

The point is, comparing the viewing cone to a white screen that can't produce a watchable image from the best seat in the house with that amount of ambient light, is not an ideal comparison. If a drop in viewing cone is a key concern, check performance with the lights off, as you would need it to be for you current screen, and then see if you can live with it. In a bright room, being able to see a good image from anywhere is an improvement over the white screen that you have now.

I would also test it with some static content with solid colors. I use the netflix selection page, as an example, because it is often harder to tell with movie content which is different at every point on the screen. Perhaps the sample happens to be on a dimmer part of the screen. ...

Finally, I would say that testing those tiny squares in front of a white material (or any brighter screen color) is going to make the darker material look artificially worse, in a way that does not reflect reality. It is a similar effect to comparing plasma TVs to LED backlit models in Best Buy. Side by side, the plasma screens look super dull. Almost too dull to watch. While they are not as bright certainly, they don't look that dull when you get them home. In fact many people, including me, prefer the image from a plasma screen over an led lcd. Our brain is drawn to the brightest screen.

When I test new black screen materials, I make sure to do it individually before deciding if it works or not. A number of black materials that I initially dismissed, turned out to be viable when I revisited them individually. This will be especially important with the BD 0.8 gain material. Try it again without any other screen and I bet it will seem brighter to you.

As fun as side by sides are, and as great as they are for marketing, our eyes won't let us get an accurate view like that. Rating performance out of 10 individually is your best bet in my opinion.








Quote:
Originally Posted by Sancho101 View Post

I ordered some screen samples of the Black Diamond 1.4 gain and .8 gain. I currently have a cheap $100 108" 1.0 gain screen with an Epson 8700UB 1, 600 lumen projector. I'm not impressed with the Black Diamond screen samples I received. The off axis viewing is really poor.

I taped the samples to my existing screen. The 1.4 is on the left and the .8 is on the right. The first image below is straight on. The second image is about 45 degrees off-axis. The last one is also taken at about 45 degrees off-axis. These were taken in dynamic mode in high (normal) lamp mode with two lamps on behind me.



It looks fine when viewing straight on with the screen. When viewing even slightly off-axis the image darkens substantially and has a strong blue tint. Not exactly something I would want to use for watching sporting events with a large group of people in my living room which is why I even considered such a screen.
post #134 of 344
Thread Starter 
Check out my rigid black-screen design. Same principles except that each layer is a rigid substrate instead of fabric. I managed to drop and crack my front hard coat as soon as it was delivered so I reordered but you get the idea.

Any thoughts on the design with the transparent outer frame?



I tested it and it works fine. I may have underestimated the weight of the sheets though. Individually, the layers are not that heavy. Together, it is heavy enough that hanging it is a problem. Still, it look nice though (if I do say so myself). I think I need to work on a hybrid that uses a mix of rigid sheets and fabric to reduce the weight.

More to come on the rigid black-screen. The aim is to finish the screen with a design that rivals the expensive commercial options. I actually prefer the way this one looks but I would. It's a shame it's so heavy....
post #135 of 344
Quote:
Originally Posted by New Design View Post

As fun as side by sides are, and as great as they are for marketing, our eyes won't let us get an accurate view like that. Rating performance out of 10 individually is your best bet in my opinion.

Agreed 100%. I'd go further and say the PJ should be calibrated for each sample.
post #136 of 344
Quote:
Originally Posted by New Design View Post

Check out my rigid black-screen design. Same principles except that each layer is a rigid substrate instead of fabric. I managed to drop and crack my front hard coat as soon as it was delivered so I reordered but you get the idea.

Any thoughts on the design with the transparent outer frame?

I tested it and it works fine. I may have underestimated the weight of the sheets though. Individually, the layers are not that heavy. Together, it is heavy enough that hanging it is a problem. Still, it look nice though (if I do say so myself). I think I need to work on a hybrid that uses a mix of rigid sheets and fabric to reduce the weight.

More to come on the rigid black-screen. The aim is to finish the screen with a design that rivals the expensive commercial options. I actually prefer the way this one looks but I would. It's a shame it's so heavy....

My guess is that the transparent outer frame will have issues, reflections, glare, etc. As far as the rigid substrates being heavier, I'd think the effort to hang it properly would be less than the effort to get the fabric substrates smooth...
post #137 of 344
Thread Starter 
Quote:
Originally Posted by Kirnak View Post

My guess is that the transparent outer frame will have issues, reflections, glare, etc. As far as the rigid substrates being heavier, I'd think the effort to hang it properly would be less than the effort to get the fabric substrates smooth...

The transparent layer is anti-reflective glass with a 97% light transmission. It covers the whole front but is an inch and a half wider on all sides than the other layers to give the effect of a transparent frame. It doesn't have any issues with glare or hot spots but your comment about hanging it is absolutely right. Although it is lighter than an equivalent black diamond zero edge, it is heavy enough to be an issue for me to move around on my own. I can see why rigid screens are best suited to the custom install market. 2 people and a commercial strength hanging solution are a must. I would be worried about ripping the wall out with this one.

It is back to the drawing board with that design. I like the look of the glass front but I need to cut weight somewhere else. My current screen uses foam board as the rigid layer and the whole thing weighs less than 10lb. I was thinking of using carbon fiber or fiberglass which are both strong and light. Foam board is too fragile to hold other rigid layers.

It has taken me a while to learn how to create large flat sheets without air bubbles but I think I have cracked it. They can be a single layer which can be rolled to and the resin can be used to attach a reflective film which would be lighter than using a rigid reflective layer.

If anyone has made a screen using carbon fiber, I would love to see some pics. I will post some of mine when I finish a prototype.
post #138 of 344
Thread Starter 
While not related to the back-screen thread directly, a member asked me about a silver screen design using diffuser film so I thought I would post a few pics of a test I did a while ago. The material used a layer of mylar which was stuck to a double sided diffuser film with transparent envelope glue which was sprayed on. Here is the test strip:


I would estimate that it has a gain of at least 3 (a guess made without any measuring equipment). Areas with solid light colors were super bright:


All the gain in the world doesn't help with blacks in ambient light. With modest room lighting, you can hardly tell there is meant to be a black background, even with a high brightness projector:


With film content, the effect is mixed. The colors are super bright but the lack of contrast makes for a poor movie watching experience with the lights on:


On the other hand, it is a really cheap method of creating a silver screen for 3D. For some reason, silver screen fabrics tend to cost a fortune in comparison to white and grey. Silver screen paint is similarly much more expensive. Very few of the diy silver screen fabrics that I have seen are great performers either. This method results in a super high gain screen which is perfectly smooth and has no hot spots. I was able to create a 100 inch 2.40:1 piece for less than $30 (using rolls I already had). Unfortunately, it may be hard to purchase only that amount of each material so you would spend more and have some spare. for black-screen builders who already have a roll of mylar and light diffuser film, it is a good way of creating a second screen to be brought out for 3D viewing if extra brightness is needed.

If you have a dim projector and watch in the dark, this method lets you squeeze extra lumens from your set-up for a larger screen. It would still be cheaper than most diy silver screen options even if you didn't have the materials in stock.

It is hard to capture the brightness in photos for this one so you will have to take my word for it until you try it. You can see some extra brightness but you can't see that it is 3x brighter than 1.0 gain white screen materials. I think that is a limitation of my camera.



It is a fun experiment to try though. most high gain diy solutions are disappointing so finding one that isn't is always fun.
post #139 of 344
Quote:
Originally Posted by New Design View Post

The transparent layer is anti-reflective glass with a 97% light transmission. It covers the whole front but is an inch and a half wider on all sides than the other layers to give the effect of a transparent frame. It doesn't have any issues with glare or hot spots but your comment about hanging it is absolutely right. Although it is lighter than an equivalent black diamond zero edge, it is heavy enough to be an issue for me to move around on my own. I can see why rigid screens are best suited to the custom install market. 2 people and a commercial strength hanging solution are a must. I would be worried about ripping the wall out with this one.

It is back to the drawing board with that design. I like the look of the glass front but I need to cut weight somewhere else. My current screen uses foam board as the rigid layer and the whole thing weighs less than 10lb. I was thinking of using carbon fiber or fiberglass which are both strong and light. Foam board is too fragile to hold other rigid layers.

It has taken me a while to learn how to create large flat sheets without air bubbles but I think I have cracked it. They can be a single layer which can be rolled to and the resin can be used to attach a reflective film which would be lighter than using a rigid reflective layer.

If anyone has made a screen using carbon fiber, I would love to see some pics. I will post some of mine when I finish a prototype.

My biggest concern would be safety of the sharp glass edge. The sharp edge of the glass surface should be covered with a sturdy frame.
post #140 of 344
Quote:
Originally Posted by New Design View Post

On the other hand, it is a really cheap method of creating a silver screen for 3D. For some reason, silver screen fabrics tend to cost a fortune in comparison to white and grey. Silver screen paint is similarly much more expensive. Very few of the diy silver screen fabrics that I have seen are great performers either. This method results in a super high gain screen which is perfectly smooth and has no hot spots. I was able to create a 100 inch 2.40:1 piece for less than $30 (using rolls I already had). Unfortunately, it may be hard to purchase only that amount of each material so you would spend more and have some spare. for black-screen builders who already have a roll of mylar and light diffuser film, it is a good way of creating a second screen to be brought out for 3D viewing if extra brightness is needed.

Won't the diffuser film de-polarize the light, cause crosstalk and ruin the 3D effect?
post #141 of 344
Thread Starter 
Quote:
Originally Posted by Chrodarcniss View Post

Won't the diffuser film de-polarize the light, cause crosstalk and ruin the 3D effect?

I am told no but I haven't tried it myself. I don't care about 3d movies at all. Most 3d set-ups at home use active 3d designs which work on any screen. Active 3d always looks really dark to me and people with less powerful projectors find that to be a huge issue. For that type of user, all they need is extra gain and a good smooth surface.

One of the manufacturers who I bought diffuser film from, specifically called out that it doesn't interfere with polarized light. like I said though, I haven't tested that personally and also, I don't know if that applies to all diffusers or just their diffusers. I can't see any reason why their ones are special though. If you test it and find out, please let us know. My bet is that it will work without any issues.

On passive set-ups, there is more than one kind these days. The traditional 2-projector set-ups that require a silver screen and the newer kind which claim that you don't. I have a ProjectionDesign projector and I was reading about their passive 3D technology on their website. They claim that their 2 projector passive 3D technology does not require a special silver screen and works with any screen.

I am fairly sure that any projector screen will need act as a diffuser regardless of it being used for 2D or 3D content.
post #142 of 344
Thread Starter 
I will explain these in a bit. Pics from test with 30% tint

1


2


3


4


5


6


7


8
post #143 of 344
Thread Starter 
I wanted to add some updated information based on some recent material tests. I have been working on the assumption that all window tint brands are created equal as long as you select one with the right amount of light transmission. As some of you know, I use a charcoal pvc material for the dark layer on my black-screen, not window tint. I have tested window tint in the passed and had good results with it.

The latest testing gave me different results that I had seen with other brands of tint. Image 1 shows a piece of 30% window tint. The 2nd image shows how black it looks when held against a reflective layer. These films always look darker or lighter when you add an layer underneath unless they have no light transmission. This one looked almost completely black.

The 3rd and 4th pics show how it looked when I made up a finished screen sample piece. It looks a little creased as I used some old left over diffuser film for the test and it has seen better days. That aside, you can see that the result is a fairly dark looking screen sample. The image doesn't accurately reflect how it looked in person. It actually looks a little darker still, but without light shinning on it, I couldn't capture a photo of it.

Images 5 and 6 showed that it gave a decent image from front and canter. Image 5 shows that even with the lights on, it gave black blacks and bright whites. Head on, it actually looked slightly brighter than my screen. Where if was different, was off axis viewing. In my screen, the front 2 layers both have a light diffusing surface. This allows me to get away with a thinner, more transparent diffuser on top. Together, I get a fairly even level of brightness.

The glossy near black window tint gave a far narrower viewing cone. I am not sure if it is because this sample was blacker that previous window tints I have experimented with, or a limitation from using only one diffuser. Images 7 and 8 show the difference in brightness between on-axis viewing and off-axis viewing. I would note that with the transparent diffuser on top, I got no hot spots from the glossy tinted layer underneath. It is well know that black screen materials have a narrower viewing cone so one that is this close to black is bound to have a narrower cone than my charcoal material.

Perhaps that trade off might be worth it for owners of less powerful projectors who only watch from on-axis seats. For me, I would consider this sample to be too dark and limiting. With this brand, Ii would have chosen a lighter film with higher transmission to give a broader viewing cone. As an alternative, I would add a second layer of clear diffuser film between the reflective layer and the tint. This probably explains why the LG screen has its diffuser behind the tinted layer. It then uses its anti glare hard coat like I use the transparent diffuser.

I just wanted to add that update to save somebody from buying tint that is too dark for their set-up. Make sure you get samples first before buying a larger roll. It seems like there is some variation between the properties of 2 films with identicle light transmission from different brands. I don't remember what brand I tried last time which doesn't help much. I am not saying this brand doesn't work, just that I would have gone with a 35% or even 40% tint with the brand. Last time, I used tint, I used 2 layers of 50% tint which were light in appearance individually, but black when held together .
post #144 of 344
Thread Starter 
Quote:
Originally Posted by Sancho101 View Post

My biggest concern would be safety of the sharp glass edge. The sharp edge of the glass surface should be covered with a sturdy frame.

What makes you think it is sharp? You can get glass with smooth polished edges and even rounded corners. Even a frame can have pointed corners. I think any concerns with safety could be addressed with the right finish and right strength material. Especially if it is screwed into the wall.

Compared to flatscreen tv's of an equivalent size, even this lot of materials is far lighter. Of course you wouldn't be a happy camper if either of them fell on you.

This particular front glass has a different issue. It isn't strong enough. A fall would break the screen as much as the person it fell on. I am getting some tempered anti reflective glass with polished edges which is apparently much stronger. We'll see.
post #145 of 344
Can you tell me how you are able get each layer to adhere to eachother? How do you avoid getting air bubbles?
post #146 of 344
What do you guys think of using the rosco light translucent screen as a diffuser layer to put in front a reflective layer?
http://www.rosco.com/stage/screens_tech.cfm?menuReturn=#rear
post #147 of 344
Did this thread die out or what?

Is there anybody who PM'd New Design about what specific materials, and more importantly, links to where they can be ordered? I'd really like to give this build a shot, but i don't have the extra cash and/or time to experiment with different materials myself. Since New Design has already done plenty of testing and narrowing down of which combinations give the best result, as evidenced by his completed black screen hanging on his wall, i just need to know his specific layer by layer material list for the build.

If nothing else, i'd at least like to know exactly what he used for his diffuser layer and his "charcoal rear projection material" layer. For these two elements i'd rather buy exactly what he's using than order 20 different samples of each and figure it out on my own, so a specific brand and/or link to each would be extremely helpful.

I've tried PM'ing New Design myself, but it doesn't look like he's even visited the avs forums for over two weeks, so i'm hoping someone here got the relevant info from him in earlier PM's.
post #148 of 344
Thread Starter 
Hi black screen fans

I haven't been on here in a while for various reasons. I have however been in the lab working on some improvements to the black screen design and, trying to solve, what I believe to be, one of the biggest diy mysteries there is. Namely, how do you stick 2 pieces of material together, when one is translucent, without there being visible adhesive marks, air bubbles or the material shriveling up? It sounds like a simple task in comparison to some other DIY issues, but it isn't'. You would not believe the amount of time and expense I have invested in researching this problem.

UP until now, I have joined my layers of material together by attaching them all to a rigid flat surface. By pulling them all tight and stapling them at the back, the tension was enough to hold them all together. I was happy with this method because it worked well and the absence of an adhesive improved the overall performance. The adhesive used to bond layers in most commercial screens can reduce brightness by around 8% for every layer of adhesive. The more layers, the more brightness is lost. In the interest of disclosure, the reason I have been working on this point is because I plan to release a commercial black screen for my business. I feel it is important to state that as I no longer consider myself to be an independent view on screens. Some of you know that I started the project because I was not satisfied with the commercial offerings available. Specifically that they were all outrageously priced and deliberately misleading in their advertising. I plan on putting my money where my mouth is and releasing a genuine low cost alternative that is affordable for everyone. Well, nearly everyone anyway...

For the commercial screen, I am using a hot stamping process to bond the layers which I have found to be preferable to using adhesives. This is difficult to achieve as a diy project without buying expensive and large equipment which would be silly for a one of screen project. In the spirit of this diy thread though, I still wanted to share some of the results of my tests in case somebody has a need to use an adhesive for their diy screen. This would be in scenarios where it is not possible or desired to buy a separate rigid layer. If you want to just use the wall to attach the materials to, for example, you would probably need to use some kind of adhesive to hold the layers together with no gaps. Anyone who has tried this, will know what a nightmare it is. Firstly, a significant number of glues will melt the PVC fabric and make it shrivel up. Secondly, even glues that claim to dry clear are normally still visible through the near transparent top layer. thirdly, sticking all the layers together with no air bubbles can be like trying to thread a needle using 2 bricks in terms of difficulty. I tested over 20 different adhesives and most ending up destroying my screen materials. I did find one method that is worth sharing.

Firstly, and this is important, find a water based glue that claims to dry clear. This should not be hard as they aren't rare. what they don't tell you is that they only dry clear if the layer of glue is thinner than you could evenly spread by hand. I figured that an advantage of water based glue is that they can be diluted with water to thin the mix. I added a little water to my glue and it spread a lot easier. It kinda looked like milk:



Next, I spread it on my dark layer using a foam spreader. Note how it still looks white at this point, even when thin:




It is important to clean both layers before applying the glue. Any bits of dirt and glue will gather around them and leave white marks on the screen. once it is clean, apply the glue and material straight away without leaving enough time for dust to gather again. might be a good idea to vacuum first too.

When you lay the transparent diffuser film on top of the dark layer, all the expected problems like air bubbles and visible white glue will become obvious. But, you planned ahead so no problem. You take a wide spreader or even a credit card and flatten the materials together. You then gently push all of the excess adhesive to the edges of the material. Don't worry about the edges because you will cut them off when it is dry.


With the watered down glue, it should be relatively easy to do this:


The vacuum you create by doing this as well as the smoothing effect will leave you with perfectly flat and smooth bonding. The remaining adhesive layer will be far thinner than you could get by using a brush and it will dry clear, just like when it is applied by machine. Note what I said about dirt. I didn't clean this sample material properly and you can see the dirt marks:


BTW, another design improvement is a new reflective layer which is many times thicker than mylar and has a black backing for extra strength. Mylars mirror finish gives very directed brightness which results in a visible increase in brightness between standing in the center and watching from the sides. This reflective material has a texture which spreads the brightness more evenly to give me a wider viewing angle with the black material. For those who do not need the extra brightness this is a good idea to give better uniform brightness and wider viewing when the lights are on.



The thicker reflective layer is a lot easier to work with. trying to stick thin mylar films without getting creases was near impossible for me. If you plan on using an adhesive, I can't emphasize enough, the importance of buying a thicker reflective material.

Once dry, using this reflective material, my new dark layer which is near black gave very good results. The lift in black levels you get from a darker screen is very noticeable. With the lights on, the black level performance compared to white or grey material is, well, night and day:

TBC
post #149 of 344
Thread Starter 
With the lights off, the inky looking blacks were at near oled levels:


With the lights on, there isn't even a hint of wash out:


Here is a close up of the screen material surface:


Colors look vibrant against black with the lights on too:


If you plan to use adhesives, I suggest testing your process on smaller samples first to make sure your mix is right. It is very easy to ruin your screen. If anyone knows of a better method of applying transparent adhesives without leaving visible marks, I would love to know too. OTher than water based glue, UV glue might be an option. I have some, but no UV curing lamp. The UV glue seems to give my materials a greasy look that causes hot spots but I don't know if that goes after curing yet.

I know I have a lot of PMs to reply to. I promise I will answer everyone shortly.
post #150 of 344
Great thread. I am enjoying reading it.
Edited by bruce can - 12/21/13 at 10:19pm
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: DIY Screen Section
AVS › AVS Forum › Display Devices › Screens › DIY Screen Section › DIY black screen tests