Hi all,

Yesterday I purchased several yards of a thin black-out cloth. At $6 a yard, it wasn't the cheapest bolt on the block but the weave was tight and it had a very smooth side, rubberized maybe... it was hard to tell. Light could pass through it somewhat when held up to the light and that was just what I was looking for.

Blackout cloth of the thicker variety that blocks all light seems to be the material of choice for most projection screens. Since no light gets through it you could say no light is really lost (sortof). Some people have tried putting mirrors behind different materials but that seems a little drastic to me. They call it light fusion. I've been thinking about something inbetween.

I thought maybe using a good white tightly woven cloth and applying a shiny layer of aluminum foil to it's back might serve to make a fairly bright screen without hot spots. Any light going through the material would bounce back into the material, hopefully making the material glow a bit brighter. Everyone has aluminum foil and it's easy to apply to cloth that has been stretched tight on a frame and sprayed with a light adhesive.

So... I done did it!

I started with a frame...

I used 1 x 3" pine, 45'd the corners and glued, stapled and screwed on some thin plywood gussets to the corners. I believe in lots of drippy glue folks... that's where the strength comes from. The staples and screws are only there to hold it while the glue dries.

I cross braced the frame before stretching the fabric on it. This cross brace will be removed later and cut to fit INSIDE the frame so it doesn't stick out later. That way it will sit flat on the wall. For now, it is up in the air because I need room to work under the brace. You'll see why in a minute.

Close up of the cross brace...

After stretching the fabric good and tight, using staples AND GLUE around it's edges, I sprayed a light coat of adhesive in a "foil - wide" swath down the fabric. Then I started unrolling aluminum foil (shiny side down) onto the sticky adhesive.

Now you see why I put the brace the way I did. I needed access to run the foil under the brace.

Yes... it's a bit wrinkled, but I got a lot better at it as I went along. I got my son to help me. The second set of hands really helped. The process took maybe thirty minutes to foil the whole back of the screen.

I'm sorry I didn't take more pictures but you get the idea.

Screen cost: $16 for fabric. $2.50 for adhesive, $2.00 for aluminum foil, $12 for wood and glue. Under $35 for all.

No pictures yet from my PJ, though I watched a Star Wars on it last night. I'm rather tickled with how it came out. Very light weight. Note it hanging from the wall on fishing line.

I recommend the process. All done in an afternoon, start to finish. No hot spots. I'm still working on my PJ. I have some brightness and noise issues. Will get them squared away soon I hope.

I have some black felt to put on... today maybe.

Regards!

Ross

Great idea rossrfree. It might be helpful to take some screenies with no foil behind one section for comparison. You might also want to try a test patch with mylar behind it. Mylar usually has significantly higher reflectivity than aluminum foil.

Ok, you've got my attention. Where do I find mylar in the quantity we need for a nice reasonable price? I actually messed up on the size of my screen. The cloth is 54" wide so I made the frame 50-1/2" tall. So how wide should I have made it? I was thinking six by nine but that obviously was wrong.

Anyway, I'll probably be building another one just so I can get those dimensions right. If mylar works better, I'll be looking into it.

Thanks for the compliments,

Ross

Has anyone tried a test of just a plain white bedsheet with mirror mylar behind it?, I would not use the spray adhesive between the front surface and the reflective surface you will be defeating the purpose of reflecting back the light with the mirror, maybe use still cloth as a base layer, then spray adhesive to then then aplly the mylar you should have a smooth surface then just overlay the bed sheet ontop. (maybe doing this all vertical will help once the bace cloth is framed).

In the camping section of many stores they sell emergency blankets guess what they are made of, yes Mylar.
Its quite thin and it is folded but it may be worth looking at I use it in my grow room for the walls
.

Brian kc0kfg

ebay has some 1 mil and 2 mil mylar in 50-55in widths for a reasonable price.
rearden

ebay has some 1 mil and 2 mil mylar in 50-55in widths for a reasonable price.
rearden

I remember the "space blankets" made of mylar. They're folded into the size of a rubitz cube (sp?). I also remember being able to see light through them... like a pair of really dark sunglasses. Still... light passed through.

So... why would this be better than aluminum foil again? The foil lets no light through. It comes in inexpensive rolls. It's size is definitely easy to handle. And if I botch it I can run to walmart and pick up another roll.

I'm sorry I don't have any good pictures yet to show off. But alas, I am afraid they do not truly compair to those others have taken. I still have issues with my ballast and lamp.

Here's a couple on the new screen...

The rings you see are from the digital camera. I do have some fresnel rings on the right side but they are hardly noticable. Will tweak them out later.

These pictures are a bit dark... I am trying to improve them. I still do not have a reflector on this projector yet. The movies are definitely watchable! Cudos to LUMENLAB!

You can see the picture overlaps the screen. It falls off onto the painted wall behind (pinkish mauveish... whatever that color is ). If you look closely near the boarders of the screen you will see where the wood frame is slightly darker (very slight) than the foiled area of the screen. The foil only goes up to the edge of the wood.

Again... the rings you see in the digital pictures are not there on the screen. The picture is about as dark as is represented in these digital pictures. Yep... a bit dark. Still... no reflector and I think some ballast issues that may affect brightness quality. I keep the room dark and it makes the projection look just fine.

I really like the screen. It's very light weight and only 1" thick. I'll probably build another the same way but to the correct size for a wide screen projection (2.45 : 1) (?). Something like that. Got to see ALL of StarWars!

Again I would say... go with the foil for simplicity and availability. The screen is watchable from darn near any angle. No... I repeat... no hot spots at all. Thinner material would likely allow foil to show and start creating hot spots. I am using a 250 : 1 contrast LCD. The pits! And still I'm getting one heck of a picture! I can't wait to scale up using a nicer monitor. "Ummm... no dear, that wasn't me talking. It was the TV!"

Whew! That was close!

I made yet another screen over the weekend. It's 113.25" x 50.5" including a 2" black felt border around it's perimeter. I used the same materials and technique except for the foil. I went (as suggested) with the aluminized polyethylene (didn't have mylar). It was more reflective than the aluminum foil and came in a sheet roughly 60" by 80" or thereabouts. I used the same adhesive to put it on and a hand from my daughter. The material came from our favorite store... Walmart... out of the camping department. Ye ole safety blanket (ie "space blanket"). It was easy enough to use and with the extra hands went on with a minimum of wrinkles.

Pictures to come soon!

Ross

you should do test samples to get the comparison shots, otherwise you go off of memory and the mind can trick you in thinking yea this is brighter than before. Also I do not think BO cloth is the best candidate for the mylar backing, Remember the material will need to pass light twice, the bo cloth will block most of what you are trying to accomplish.

Joe

Hi Joe,

Yes, I'm aware of that. This is totally unscientific. No before and after. Nuttin. This is completely seat-of-tha-pants action at work.

The BO cloth I am using is thinner than most but has a very tight weave with a very smooth side. I don't know what's on it but you can scratch it off with a fingernail. It'll likely get trashed by kids in time but I don't care. You've got to know what to worry about in life.

Anyway the BO cloth allows some light through. Not a lot but any through is lost light... so the aluminized poly will play a part. How much is anybodies guess. If you read from the beginning you'll realize I'm not trying to make the perfect glowing screen... rather something between hot and cold.

I've ordered the brighter LL pulse-strike lamp and reflector. That should make a big difference in illumination. Then I'll get some pictures posted. But I'm liking the new screen anyway.

Still... I sorta wish I'd just order the wider BO cloth. I'm limiting myself to the 54". After stretching and border, that's 46-1/2" high. But it's freakin wide! Ha! I can watch Star Wars at 2.35 :1. That's the largest wide screen format I know about.

I'll get some pictures of the screen shortly... tonight maybe.

Ross

I sandwiched the space blanket with a piece of white bedsheet muslin purchased from Hancock Fabric. Then just the bedsheet over a piece of blackout cloth. The mylar sheet combination was a little brighter, but there were parts where a true mirror reflection came through and was distracting. IMO, the mylar doesn't add much. In fact, the white muslin bedsheet didn't add much from just using the lighter side of the blackout cloth.

Insofar as a homemade "roll up" screen, the single piece LL BO cloth is the most convenient, especially given the 110" width. Any substantial improvement would come from more specialized materials (e.g. Dazian, etc.)

For a stationary screen, I've seen the Goo Systems product which looks like a reasonable investment. But has anyone tried the Pearlescent finish at HD applied over a white painted wall? One qt. is $20.

My new screen with aluminized polyethylene

It's 2.35 : 1 or about 109" x 46.5" viewable. Star Wars Rocks! This is the foil going on...

One more from the back...

Is that 16:9? It looks way too wide....

michaels sells silver sheets in their posterboard section that are about 20"x24".
they have 95% of the reflectiveness of a mirror. actually they are so shiny you
could use them as a cheap mirror.

they run at about $3 a piece. 10-12 pieces would take care of most peoples needs.

Yeah, it looks like 2.35:1 for me. That's what they use in the theaters.

If you're gonna size a screen... go for the 2.35:1. Many of the great movies out there are in this format. I've only seen one wider (2.40:1).

Ross

I would recommend to go for 1:85, some movies are in that format. If you go with a 2:35, the image would not fit vertically.

have you tried to look through aluminium foil? if you hold it up to a light I'm quite sure you'll be able to see through it, you can also see through CDs as long as they don't have a label on them.

that said I think aluminium foil is probably the best bet for the reasons you said, I've worked with mylar quite a bit and it isn't easy to stick down flat and it tears very easily.

this is a good idea and I'll probably give it a go when I get roung to making a screen.

Transparrent aluminum? I think you may have watched Star Trek 4 too many times...

I'll ask again, have you tried? go on try it, hold it up to a bright light and put your eye real close.
why would you assume light can't pass through a very thin sheet of metal? there just aren't enough electrons there to stop it.

also, again, you can look through CDs (which are made of aluminium) try it!

Star Trek tech has a funny way of becoming reality....

You can check out transparent aluminum here:
http://www.livescience.com/technology/051018_new_glass.html

thttht!

Heh. No light gets through the aluminum foil on my bedroom window.

I think it was Joe asked this earlier...

In my old projector's new home, they were using a bedsheet for a screen. The sheet was simply tacked up onto open studs (They were forced to remove the material over the studs due to a flood. )

I suggested that they put a backing behind the sheet (The picture was actually nicer from the backside of the sheet. RPTV anyone?) and they used emergency blankets. Result? Excellent.