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Home Theater – Build a Mega-Screen

I’ve been watching TV on front projector since 2006, and it came to the point where, um, a 10′ screen just wasn’t big enough anymore.   You know how it is…

screen(click to enlarge)

So my budget was intended almost exclusively for the projector and not screen, and I began looking around and quickly found that plywood, siding, masonite, sheetrock, etc never comes in widths greater than 4′, so that was out.   Formica comes in 5′, but that would also have required a seam which I may or may not be able to disappear.

So I came across linoleum, or what the kids today call ‘vinyl flooring’.   12′ widths, unlimited length, and cheep as dirt.   Lowes has it for 45 cents/sqft, so a screen as big as I can manage for $72!   As a bonus I can take it apart and roll it up when I move.   But, judging from a search, no one had ever tried this before for a screen, so I was in uncharted waters. (again)

Now; this stuff has a reputation for curling, and this is because of the different coefficients of expansion between the plastic layer and the paper backing.   Of course my intention is to paint the paper with Black Widow, a special color-balanced formulation of screen paint, and so the idea would be to first seal all moisture out of the paper so it stays flat.

So I got four samples from Lowes and two from Home Depot.   I washed the paper back of all my samples for ten seconds under the faucet, to simulate a worst-case coating of paint.   My four samples from Lowes all curled parabolically across the whole surface, and unacceptably, particularly at edges.   This is regardless of paper thickness (factor of 3), and on samples priced from 45 cents to $1.10/sqft.   However my two samples from Home Depot were much better. (66 cents/sqft each)   Both are Armstrong “Metro”, one with an octagonal pattern and one with a square pattern on the plastic side.   The octagonal is bent a bit, evenly across the surface with no emphasis on edges, but the square one had almost no deforming at all.   This is Metro Agean Mist White @ 66 cents/sqft.

These samples are all from Armstrong, but the main difference between the Lowes and HD samples is the nature of the paper.   HD samples’ paper is slightly darker gray, I don’t know why.   But it deformed far less, and there is almost no edge curling as was so evident with the Lowes samples.   Once the samples were dry and results conclusive I suspended a sample full of water (like a cup), to see whether the plastic side is porous…   it is not.   So I bought my vinyl, 130.5″x76.5″, to give a 12′ screen after I add my frame.   Do yourself a favor and just have HD rough cut it, and you trim it to size with a sheetrock square;   I had to fight with them to make them use their machine to cut it, on the theory that it will make a nice square cut, but what I ended up with wasn’t particularly accurate in size.

I couldn’t paint the wall because I was renting, and I had dark wood panelling in the theater at the time, so I started out intending a 16′ screen, but some checking showed that my projector wouldn’t be bright enough.   So then I went to a 14′ screen, but I found that the dimensions are so large that one person couldn’t reach the top to move it around.   Thus a 12′.   Still looks like a monster.   Keep in mind that screen area is not linear to dimensions;   a 10′ diagonal screen is 48sqft, whereas a 12′ diagonal screen is almost 72sqft, or 50% larger! (use trig)

Of course to calculate your screen size in square feet, simply multiply screen width by screen height if the dimensions are already in feet.   If you only know your screen size in inches, multiply screen width by screen height and divide by 144   —   this will be the size in square feet, and also a good guess at how much paint you’ll need in fluid ounces.

About aspect ratios:   The goal should be to make your screen the aspect ratio of the content you’ll be watching the most, in my case HDTV so a 16:9 aspect ratio.   Movies are generally 2.20:1 or the old 2.39:1 so you’ll have black bars on top and bottom with movies, but you don’t notice them.   OTOH if you make your screen a movie aspect ratio, when watching a 16:9 show you’ll have black bars on the sides and a smaller picture.   So for me 16:9 is the best balance of viewable area and wall usage.   With 16:9, if you know your screen width, divide it by 16 and multiply that by 9 to get your height.   If you know your height, divide it by 9 and multiply that by 16 to get your width.   Simple.

It is important to keep moisture from the paper backing, to prevent curling from differing coefficeints of expansion between the plastic and paper, so I decided to go with a cheap semigloss primer.   Years ago I owned an apartment complex, and I made sure that semigloss was all we used.   Once, we had a roof leak, and the semigloss paint on the apartment ceiling came down in a 2′ bubble full of water, rather than letting the water through!   This tells me it’s a watertight plastic coating, just the thing for sealing this linoleum backing paper.

Side Note:   I have no reason to believe that Kilz2 or other conventional primers are water/airtight.   Killz in general, looks like hype to me…

So I bought a quart of bright white semigloss (Evermore EM6411) and as it was Base 1 I had them fill it to the top with white pigment, to try and get as much out of it as I could.   I diluted it with water (1/4 can) so it will integrate into the paper better and for the same reasons Black Widow is diluted   —   to form a more even, thin surface when dry.   The correct viscosity is described as flowing between the tines of a plastic fork.   I can tell you though, that for a 12′ or bigger screen, a quart of diluted primer is not enough when rolling two coats.   The first coat went on well and laid down just fine as it dried;   but I was so low on paint for the second coat that I pressed on the roller to spread it, and this left permanent texture on the surface.   Do yourself a favor and get a gallon of primer…   it costs only a little more.

I was unfortunate enough to have a paper bubble right in the center of my screen, where the paper had delaminated in manufacture, about 1.5″ in diameter.   This only became evident when I was putting on the first coat.   I lanced one side of it with a razor and filled under with paint, smoothing it over.   Turned out fine.   I also noticed some waviness in the vinyl, as vinyl does, but that substantially relaxed and flattened out as the paint dried.

Now for the open-source Black Widow screen paint.   I was a little worried about BW as my projector (Planar PD8150) is bright enough only by a small margin, and so Harpmaker over on the Home Theater Shack forum patiently worked with me on an experimental formulation of BW called Black Widow -X1:
4oz AAA-Fine
4oz AAA-Medium
1qt Valspar UPIFE Bermuda Beige cut significantly with white paint.

The idea is that the AAA-Medium is lighter than Fine, and so needs less red tint to offset.   Harpmaker recommended mixing one quart BB with 1 quart white, and he tested this for me.   The goal is to get the color response of the paint to be as flat as possible, so that all colors are reflected truly.

Well, take my word that it is very flat, except for a small hump at yellow-orangish and slight dropoff in deep red.   81.96 0.26 0.75   So like a smart-aleck I thought I’d improve on that, and to my quart of BB I added .75qt of white, to try and increase the red push.   Mixed it up, poured off to a quart, and added my AAA-Fine and -Medium.   I was glad I chose a very light semigloss primer as it will also help gain, as it seems some light penetrates the BW and is reflected by the primer.

So now I construct the screen.   To start with, here is the linoleum ready for painting, cut to 130.5″x76.5″, and backing up.   There’s no way the plastic side would be suitable for a screen, with its texturing.
unpaintedYou can see my old 10′ screen on the wall, which was just a sheet of formica, in Ice White.   It was great, but had a bit too much semigloss, causing hotspotting.

I painted as noted above, with two coats of semigloss for primer;   I can tell you that 1 quart is not enough, even though I’d diluted the Evermore by 25% to soak in and lay flat.   Then after 4 hours I painted with Black Widow-X1, as noted above.   After the first coat of BW had dried (~2 hours) the semigloss sheen from the primer coat was still somewhat visible in incident light;   not a bad thing just yet.

40oz of BW is not enough for two coats on a screen this size, as when the first coat had dried I didn’t have enough paint for the second coat, so I had to dilute it to almost watery.   I recommend that at least 60oz be prepared for screens of 12′.   But I laid down the second coat of BW and let it dry overnight.   This was my final coat, and when it was dry there was virtually no sheen from the underlying semigloss primer in incident light, which was very good news indeed!   This will mean no hotspotting, and yet as light penetrates the BW layer it will be reflected back by the primer, recovering that light for better gain.

The linoleum was laying flatter and flatter as time went on, thankfully, and after two days there was little apparent waviness when viewed straight-on.   More on this later.   I sent a sample of my paint off to Harpmaker to be tested with his spectrophotometer, and it’s about as good as it gets:

Spectral

My method of hanging the screen is unheard-of, at least on The Internets, but it works great.   I bought a nice straight 1×4″ at Lowes, the length of the screen width, to run across the top and serve as a hanger-board.   I put this under the linoleum across the top, and put heavy staples in every half-foot.   Then I put staggered staples in, between these across the top. Then I banged in each staple with a hammer, for good contact across the transit.   Unfortunately ImageShack has frickin’ lost my photos from when I posted them in 2009, so no illustrations of any of the build.

It was time to prepare the frame.   I had some leftover dark blue velvet, which turned out to cover all four sides of my frame.   Dark velvet is excellent at capturing stray light and subsuming it, better than anything else I know, and that’s what the frame should do in case there’s not a perfect fit of the projection.   I bought some 3.25″ rounded baseboard at Lowes, two pieces of 11′ each for the top and bottom.   For the sides I reused my baseboard from the old screen, which I’d previously covered in black felt.   Not trusting the theory, or even my tape measure, I laid each baseboard along the side of the screen where it would go, and marked it for length.   I made each one 1/2″ shorter than the actual screen material, so the screen edges wouldn’t show;   this turned out to be perfect.   Took each in the garage and used a tri-square to mark my 45° miter cut on the flat side, and made the cuts with a hacksaw for precision.

Took each outside and set them on blocks for covering, and pre-cut the velvet into slightly-oversized strips for each board.   I used 3M 77 spray-glue and coated the three sides evenly (not too much glue, or it will soak through the velvet and show), then laid the velvet over it, slightly stretched.   I worked along the length of the baseboard stretching the velvet and smoothing it down, first on the top surface, then on the two sides.   With an operation like this, it is important to use a forgiving glue which will let you unstick/restick as needed, like the 3M 77. (Lowes)

Then I flipped over the baseboards onto towels (to protect the velvet), and trimmed off the excess with scissors.   Pulled away the remaining velvet and spray-glued the flat side of the baseboard, to lay down velvet and smooth for finish.   I gotta say, gluing is far better than stapling for this.

Now I laid out the parts for assembly.   All there is to this frame is the top 1×4″ which suspends the linoleum, and the velvet baseboard for four sides, with four diagonal 1×4″ braces to hold it together.   It’s as light as is possible.   I cut a 45° miter in each end of the braces, and the long side was 36″.   The two braces at the top fasten to the edge of the hanger board with a screw, for strength.   You MUST predrill this, or the diagonal, ehm, ‘gusset’, will crack.   So with the screen still laid out I put in place all four braces under the linoleum, with the edges lined up with the edge of the screen, slightly recessed.   Then on the screen I laid all four baseboards comprising the frame.   I adjusted these, checking all sides several times until the whole was squared and centered, and then I stapled each corner together on the front (temporarily) with 3-4 heavy staples each to hold it all in place.   Next would be fastening these to the braces.

I’d bought a small container of black sheetrock screws, 1″ long, from Lowes.   For the top baseboard I put in a screw about every three feet, to hold it to the hanger board.   The screw heads became almost invisible against the velvet.   And I put two screws through the baseboard, into each end of each brace.   Everything was fastened together now, and I could stand the screen up!

I now put in the two screws fastening the top braces to the hanger board.

There was some bowing of the linoleum now, as the braces are not letting it hang like it should.   However the braces are necessary to hold the assembly together while it’s being maneuvered and hung.

The only way one man can move around a screen this size is from the back, lifting on the hanger board.   I am 5’10” and am barely tall enough.   So I lifted it and turned it around, ready to be hung.   I got four 3″ drywall screws and started them in certain locations in the top baseboard.   I measured the width of my room, and marked the center close to the ceiling.   I measured the screen and marked its center with a small pencil mark, and then shifted the two marks into alignment.   Then I got on a chair and lifted the screen up on the wall, about 2″ from the ceiling (I could barely lift it), held it and grabbed the screw-drill and managed to get the first screw in close to the center.   From there it was easy.   I was able to take my time and get the screen level.

Given that the linoleum is hanging, it will stretch for a while, and it was already bowing being held by the braces.   So I removed all the screws from the lower braces and the bottom screws from the upper braces, to let the linoleum hang freely in the breeze.   I left these off for at least two weeks, with the frame only being held together by my corner staples.

There was some concern that the BW coats would not bond well to the semigloss, and that it may scratch off with a fingernail, but I can tell you that’s no problem here.   I put down the BW within 4 hours of the primer, so volatiles hadn’t evaporated and they apparently bonded well.   Also, the texture I’d pressed into the second primer coat was all but ameliorated by the BW coats.

One important consideration I had was that I need to be able to disassemble the screen, as I am renting and will move.   It turned out to be a simple thing to remove the brace screws and just roll up the screen, and I didn’t even need a protective tissue layer.

So I auditioned my new screen, and it is wonderful!   Glorious huge size, and pretty good 3D picture.   Beats all Hell out of paying $6,000 for a commercial one this size, which they cost in 2009.

(click to enlarge)
pinnoch

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