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Discussion Starter #21 (Edited)
You don’t get a lot these days for a million dollars when it comes to special purpose high speed manufacturing equipment.
The Da-Lite screens were one of their cheapest materials, I do not think their sales were high enough to support that kind of expense with such a low-priced material. I know there are silly prices in the corporate world when it comes to specialized anything, it's just like the Pentagon or Nasa paying $1,000 for a single screw.

I just wish to figure out how to create a good retro-reflective material, not trying to become a screen manufacturer.

Standard screen material is just non-textured PVC or a similar material. This is extremely cheap, the only expense is applying a surface.

Look at a piece of posterboard, it's perfectly flat with no texture and the cheapest pieces costs 33 cents (and that's after Walmart's markup). Most screen materials aren't expensive to manufacture. They spend most of the money on marketing, not manufacturing. It's a low volume item, so the MFR's overcharge on any screen material that they can convince the public is 'worth it'. Screen prices are primarily based on reputation and the ability for people to sell them, rather than cost of production. As with anything, I'm sure there are exceptions.

As far as the $200 to $300 screens by SI, ST, and Elite. Well, those come with a frame and the MFR's have to eat a lot of the shipping costs. So the cost is the frame and the shipping, not the material of the screen.
 

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Hey good luck with this!
From what i have seen of the 2.8 gain under a machinists scope, looking at an area that has lost it's beads;
They appear to have been embedded in the white surface rather than adhered with and adhesive. There are dents in the white substrate where each bead had been. My mind pictures the fiberglass backing coming down the line and having vinyl or similar sprayed on or other wise applied to it. Then entering a section containing a hopper a few inches or foot long but the full width of the material. The hopper would be filled with beads and pressurized from above with a ram or compressed air and vibrating. As the fabric slowly move under this area the vibration would align the beads as they are embedded into the wet vinyl. Every so often I will notice a sparkly on my screen and when you look at it under magnification, it is an extra bead that was not embedded as it is above the masses kind of flopping around. This is why rubbing the area with a rag can sometime eliminate the stray sparkly.
Just the guess that comes from how the material looks..
Don't have a photo of the missing beads as I loaned my sample of 2.8 to a someone on here and they never returned it.
But here is are the photos of the 2.8 compared to 2.4 which has multiple bead size and a lot more open space between the beads
 

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Spray Adhesive covered index card, waited 20-25 seconds, then began rolling the 20 Micron material over the index card until it stuck.
Did several passes. Used a Credit Card to perform the rolling.


Rolling to distribute the beads isn't going to work, because you can't avoid getting adhesive on the front of the beads. You don't want that.

Sample likely corrupted by the spray adhesive, will need to find a different application technique for testing.
The spray adhesive is altering the reflective properties of the beads. Also tried Elmer's Spray Adhesive, also corrupted sample.
Either of these adhesives may have been fine. The problem was in the application method. Also, once beads have been applied and they're "riding" higher than the adhesive layer, gentle pressure uniformly applied via an overlay sheet may be effective in embedding them properly (i.e., more securely than just gravity holding them, until the adhesive sets). We're talking grams/sqInch here.
 

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Discussion Starter #24 (Edited)
I don't think any of these application methods are going to work.
Need to have a professional fabricator do it most likely.

I don't see any way of controlling the process, these things are microscopic.
Applying pressure is just going to cause them to stick to whatever surface you push against them.

The adherence processes that I did read about were complex and not something I would have access to at home.

The original patent was in 1946, I'm going to have to read all the patents and that is going to take a while.
https://patents.google.com/patent/US2404454

There are a bunch of adherence patents, but some of them are just patent trolls.
 

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Coder
I remember reading about someone doing this with success a few years back.
I can’t find it but he went pretty in depth how he did it. He first tried mixing with paint but the soon discovered that did nothing but cover the beads. He then put them on in a uniform way and can’t remember what he used to get them to stay in place.
Long story short.
It can be done.
 

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interesting. but why don't you just buy a used one ? yeah, i know, but if you want it THAT bad ...

just an fyi, case you didn't know. i was concerned about image brightness when picking my new pj.
what i didn't know, cause i didn't see it right in front of me :eek: is how high up the pj mounts = near at the ceiling. being retro reflective, the screen throws the light back at the pj, which is NEAR THE CEILING =this is not where i sit. so, where i sit is not in the cone = image is not as bright.

now, i just noticed this, so i need to look into it further.

my point, at least for me, a screen like this "may" not be needed. and "may" be detrimental.
but, i do need a roll down. and i guess most roll downs have waves, as does mine. though when there is an image = smooth as glass.
 

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Discussion Starter #27 (Edited)
Coder
I remember reading about someone doing this with success a few years back.
I can’t find it but he went pretty in depth how he did it. He first tried mixing with paint but the soon discovered that did nothing but cover the beads. He then put them on in a uniform way and can’t remember what he used to get them to stay in place.
Long story short.
It can be done.
I've read about 3 different 'stories' about people having some success, and frankly, I have doubts if any of them are true.

I have tried about 20 different application methods with 6 different adhesives and paint with 5 different types of beads...

I will try again with different beads (larger 30-45 are coming soon, which are 1.9 refractive index).
I may have better luck with the larger beads, no idea. I didn't really have enough QTY on the 80-110 beads to do much testing.

The dust settles unevenly and there is no real way to remove the extra surface dust without ruining the original layer.

Secondly, a special chemical is going to improve this if added to the dust to separate the individual beads from each other. Then a very very very very fine applicator, a special type of sifter attached to the pressurized gun that basically blows the dust through tiny micro-holes breaking it into tiny pieces. A slick barrier wall (like one of the slickest surfaces possible on both sides to where the dust is being 'blown' over the top).

I think the dust needs to be pressure blown in a scattered fashion evenly.

That one you read might have been the Epoxy Resin story...
The people never posted close-up images to see what the material looked like, no magnified images, no microscopic images, nothing.
 

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Retroreflective material is currently being produced for a lot of things other than projection screens. If you Google retroreflective and then click on Images you even get diagrams that illustrate the various layers of the various retroreflective materials.



 

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Discussion Starter #32 (Edited)
Test Alpha Continued...

Further research has allowed me to determine that my smallest Beads were from a bad sample.
All results from Test Alpha are considered suspect due to the bead quality. Testing from Samples 1A and 1B being 20 Micron and 15 Micron were erroneous. The lumpiness I experienced is a sign of impurities, broken edges, recycled, static charge, or overly humidified - improper storage.

All future adherence testing will be analyzed by an endoscope so I can know the exact % the beads adhered over the resin, spray adhesive, or paint. Hopefully the endoscope's magnification will be enough.

In order to see if any spray patterns can get the beads adhered more uniformly,
an HPLV gun I've had sitting around unused will finally be put to use...



_________________________________________________

Endoscope

_________________________________________________

3 More samples all from separate companies are on the way...
_________________________________________________

Next Sample Group is 35-45 Microns in Size from a 150 Gram Bag, it is known as High Index Powder.
Greater than >98% roundness and less than 1% air inclusions results in a refractive index of 1.93.

The earliest the next sample is expected is in 3-5 days.

The Sample Group following that is 12 Microns, which is from a much larger 1000 Gram (1 kg) bag. Likely enough to cover a small screen say 50". Yet another 15 Micron sample in a small 50 Gram bag is also on the way.
 

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^ This may help explain why the screen companies gave up on glass beads. It was originally a fairly cheap option for lower lumen, lower definition projectors, especially for non-critical business and classroom use. But higher definition with smaller pixels required smaller glass beads......
The 2.8 beads, which according to coder, are larger than the 2.4, are plenty small enough for even 4K.

....The shops in China started off with low production costs to help maintain low screen prices but couldn't deliver consistent quality......
Quality problems only arose with the switch to 2.4. The 2.8 was manufactured for over a decade with virtually no QC problems. it's toughness and durability were beyond comparison. It was one of the least expensive screens available. They could easily have charged triple for it.

Outstanding DIY experiment, @coderguy.
Agreed!

Pip
 

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Discussion Starter #34 (Edited)
The 2.8 beads, which according to coder, are larger than the 2.4, are plenty small enough for even 4K.
This is where I found the original info on the 9 micron size:
http://www.hometheatershack.com/forums/diy-screen-development-testing/55345-glass-sand-blasting-beads-diy-screen-3.html

They were quoting Da-Lite literature, Da-Lite themselves apparently says 9 Micron, IF we are to believe them.

If it is true, my estimate is that the HP 2.4 gain screen used a mix of 3-7 Micron Beads, and the HP 2.8 gain is using 9-12 Micron Beads. Look carefully at the images he posted, and notice even the 2.8 gain beads have SOME variance, just much less than the 2.4. We'll just call it 5 Micron Sized for 2.4 and 10 Sized for the 2.8, until we know otherwise... I'll examine the HP 2.4 gain myself, but I don't think I have enough Zoom power on my scope to tell how big the beads are. I should be able to tell if they are smaller or larger than 25 Micron though.



Why would they not tell the truth?
Well, as I have discovered, the Bead MFR's sizes are like contrast ratios, they are all over the place.
So the Bead MFR could have told Da-Lite they are 9 Micron, when really they were 15-20, or even 30+.

But wait, what about the machinist scope images he posted, it's a great image to compare, but scopes have to be measurement and zoom calibrated to know exact distances that small, so it's not certain. Also we don't what the measurement scale was in that image. The usual for small increments is 10 Micron, but that would indicate the HP 2.8 beads were much larger than Da-Lite claims, and that's probably not true if we are to believe Da-Lite themselves (plus the scale is 5-increment based and not 10 based in the image). In retrospect, if the beads are bigger than Da-Lite claims, then my next test should prove very interesting, because it will be with beads sized 30-45 Microns.
 

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Discussion Starter #35 (Edited)
It is however also interesting that some expert literature claims the perfect bead for a projector screen is sized 60-65 Micron with a Refractive Index of 1.7. I don't trust the expert literature because the guy did not disclose what attributes he reviewed to consider it 'the best'.

I assume he didn't like the viewing cone of the higher refractive beads, as beads get higher in refraction, the viewing cone gets narrower.

Also, another thing that makes this incredibly hard, the pattern of bead placement affects the actual texture and quality of the screen.
I don't think I can control the pattern, but I guess since I've come this far, I'll try with the HPLV gun or other techniques.

I also have some sample GENERIC reflective projector screen material coming in from China. I do not know if it is glass beaded (maybe), but I will also try to get one Generic Glass Beaded sample as well (eventually).

Good old China Post Shipping, it might arrive next month :)
 

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Discussion Starter #36 (Edited)
Hey good luck with this!
From what i have seen of the 2.8 gain under a machinists scope, looking at an area that has lost it's beads;
They appear to have been embedded in the white surface rather than adhered with and adhesive. There are dents in the white substrate where each bead had been. My mind pictures the fiberglass backing coming down the line and having vinyl or similar sprayed on or other wise applied to it. Then entering a section containing a hopper a few inches or foot long but the full width of the material. The hopper would be filled with beads and pressurized from above with a ram or compressed air and vibrating. As the fabric slowly move under this area the vibration would align the beads as they are embedded into the wet vinyl. Every so often I will notice a sparkly on my screen and when you look at it under magnification, it is an extra bead that was not embedded as it is above the masses kind of flopping around. This is why rubbing the area with a rag can sometime eliminate the stray sparkly.
Just the guess that comes from how the material looks..
Don't have a photo of the missing beads as I loaned my sample of 2.8 to a someone on here and they never returned it.
But here is are the photos of the 2.8 compared to 2.4 which has multiple bead size and a lot more open space between the beads
I think I may have figured out how it is done, but not sure.

I did some thinking, and I think you were onto something. I think one reason the HP material appears so superior is because there is no adhesive used. I noticed something about adhesives, paint, resin ... No matter what you use it's going to create an uneven reflecting bond underneath the beads unless it is based on Titanium Dioxide (the flat white that is considered the neutral standard). The beads are reflecting the light off whatever is behind them, so if you use any adhesive, no matter how clear, you are going to alter that reflecting path because it is impossible for it to go on perfectly smooth.

I think it has something to do with a Negatively Charged Particle Sheet is placed underneath the vinyl, or the vinyl itself is charged. Then the vinyl is softened, maybe wet, maybe heated, maybe both heated and wet. The glass beads are somehow then positively charged with an agitation process, and possibly also heated to allow to attract to the negatively charged backing behind the vinyl. Then the beads are pressed into the material slowly with some type of pressing machine or a manual press.

Note that from my understanding, some of the glass particles will also hold the wrong type of charge (negative instead of positive), but I assume enough of them would be positively charged that a shaking or agitation process could allow only the positively charged ones to adhere before pressing them.

Maybe I'll try to statically charge some beads and see if I can get them to stick to a piece of BO cloth with static electricity.
It's pretty humid where I am, so it'd be hard to do, but I'll figure out some method.
 

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... I also have some sample GENERIC reflective projector screen material coming in from China. I do not know if it is glass beaded (maybe), but I will also try to get one Generic Glass Beaded sample as well (eventually). ...Good old China Post Shipping, it might arrive next month :)
Don't know if you were reading the old High Power Review Part 1 back at the end of 2016 when the discussion shifted to generic retroreflective material from China that at least one DIYer thought was usable. After some discussion it turned out that @darinp checked out a sample and thought it was too sparkly to be considered a good HP replacement.

Of course that was just one sample and among the many retroreflective materials that are already available there might be a hidden gem somewhere. But the odds are probably against it unless the material is specifically designed for quality projection screens as most retroreflective material is for general use that doesn't require great optical properties. Anyway, here's a link to that thread at the post where discussion begins on the material from China:

avsforum.com/forum/23-screens/773065-high-power-review-part-1-a-128.html#post46754953
 

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Discussion Starter #38 (Edited)
Don't know if you were reading the old High Power Review Part 1 back at the end of 2016 when the discussion shifted to generic retroreflective material from China that at least one DIYer thought was usable. After some discussion it turned out that @darinp checked out a sample and thought it was too sparkly to be considered a good HP replacement.

Of course that was just one sample and among the many retroreflective materials that are already available there might be a hidden gem somewhere. But the odds are probably against it unless the material is specifically designed for quality projection screens as most retroreflective material is for general use that doesn't require great optical properties. Anyway, here's a link to that thread at the post where discussion begins on the material from China:

avsforum.com/forum/23-screens/773065-high-power-review-part-1-a-128.html#post46754953
Yup, I saw the ordering link for Roadstar myself when I was looking through the vendors.
It was an interesting read, I may contact Roadstar and order something from them, then ask them if they know the best application method on how to adhere glass beads.

It's most likely using really large beads, so yah it's going to hotspot. Most of the reflecting fabric uses 100-400 Micron sized beads.

The goal is to stick to 5-100, with more than likely falling somewhere around 5-70. Or even more likely around 30-60.

I guess at this point, the main reason I am doing this is for the challenge. I want to see if I can beat this very difficult process, but I don't know that I can. Sure would be a lot easier if I were in the pro-fab business and had a bunch of machines to experiment with.
 

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Discussion Starter #39 (Edited)
Sample 2C just arrived (only calling it C so I can keep it in order of Micron size from now on).
Still waiting on Samples 2A and 2B...



Clarity Rating: 3 (1-10, 1 being the clearest)
Still not as clear as the 80-110 Micron sized beads I had before, but a little closer.

Potential Candidate Rating: Pending further testing
(all previous samples from sample group 1 have been eliminated as candidates)

Date of Arrival: March 7, 2018

Mix Type: Soda Lime Glass (I think)

Determination of Actual Micron Size from Microscope: Pending

Estimation of consistency of bead size: Pending

Estimation of purity of sample mix and storage quality: Pending
 

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This is really an neat project you are doing! Just wondering.. did you get a knee replacement or something.. generating a huge amount downtime? ;)
What are you using for a microscope? I would love to get something better than my $99 china machinist scope.. Something usb so I can see in detail what I am looking at with the ability to capture high quality images would be good. Did some searches the other day but not sure of the quality at the price point I am willing to spend..
Let me know if I can assist in any way, I think we are only a short drive from each other.

BTW, got me a 3D printer last month.. talk about time sucking black holes!
 
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