Rigid Torus Paint Options

You have to go with a paint that has a gain to it. The paints you mention are probably unity gain. Since the veiwing cone for these paints is 180 degress, the image will be washed out due to the screen reflecting on itself.

Aluminum paint such as that made by Tremclad is very high gain. It does sparkle a bit though. That paint plus something to get rid of the sparkles would be great for that purpose.

Any chance for some pictures or plans of your rigid design?

Josh

Tryg has reviewed paints as well as various materials and retail products and the most promising paint in his tests was simple rattle can Rust-Oleum Alumininum (Not silver, not metallic silver, just aluminum) Part number is in his thread.
Find his threads with screenshots and all in the DIY screens forum.

I'm about to try it myself as soon as I make it to a store that has it and figure out how to recreate proper application temperatures since it's too cold and wet right now here.

Application should be sprayed from a distance much greater than normal preferrably in hot or at least warm conditions where the paint is half dry before it hits the surface so you don't get uneven coverage or streaks or runs. You want several light coats and no cheating. Triple or more the distance it says to spray from on the can.

Gain will be that of the silverstar or better and if properly applied in a dusting fashion there should be no visible imperfections and it should look flat not glossy with a lightly dusted micro fine texture.

As was said previously white paint is wrong for a torus, makes the whole exercise pointless. Your end result will be a high gain screen with no hotspotting and a slightly extended viewing cone due to the dusting texture. Your tubes will thank you.

Troy

btw 8" is pretty extreme, you could do fine with half that but what's done is done I guess. You may have focus problems with that much curve depending on which lenses you have.

Gloss and semi gloss are wrong too, only flat will do.

Troy

Steve,

Sounds awesome Post those pics. Good to see you are still getting enjoyment out of your gear.

Ken./

Since VDC has white Torus screens, I am not entirely sure about washout. Having said that, the whole point of a Torus is to get higher gain. You might want to get some aluminized mylar and coat it with a clear low gloss paint.

Steve,

You won't find Rust-Oleum in Canada. The Tremlad Aluminum I mentioned is the exact same stuff. It's not a grey - it actually has aluminum in it. It's not a colour you have to have mixed. They will haved cnas of it at HD or Rona...

Troy,

Great advice on the application technique. If that does cut out the sparklies, it would really make a great high gain surface. I did some tests with it quite a while ago. Other than the narrow veiwing cone and the sparklies it was very promising.


James

"the beauty of a rigid screen is that i can always just paint over it if i don t like it"

Imperfections will show through as waves or bumps or uneven gain. Grey is wrong for crt you're right, but this isn't grey flat paint that is less than 1 gain this is like using a silverstar ~ 6 gain but with the benefit of ambient light rejection and increased contrast .

Try painting scrap stuff if you aren't sure you have a suitable paint. Then when you find the right paint and application method go to your final project. The gain will make it show imperfections more than flat white would and it would be a shame to ruin a smooth surface.

I'd still stick with aluminum even if you have to try another brand, not silver.

Troy

At some point I'm going to repaint my screen, it's real close to invisable, but I want it better, most of the problem I have had with it was the seam (2-4X12 pieces of drywall), it has to be perfect. I also have a idea for a better brush. The brush I used before was as tall as the screen was, had a foam edge to it, worked real good. The new brush should have a better edge. I may even have a professional spray it to see how good they can do.

That Rustoleum paint shows any tiny imperfection.

Deron.

Just a few tips from a professional finisher....
then a question or two.

First, I wouldn't suggest using a brush of any kind as you are not going to achieve an invisible screen "guarranteed". You will always have compromises. I am going to experiment with the aluminium paint to see how it works for me. I will also talk to my supplier to see what may be available in commercial lines that may not be readily available on the retail shelf. If I come up with something superior I will share it with you.

Second, I notice that you are tryng to create a full torus screen, in other words bending it both horizontally and vertically. Without being able to stretch the material there is no way to create a screen that will not show warpage. In one of the puctures you can see the shadow created by the uneven shape. This will show up in the picture.

I am interested in building a torus screen for myself and my daughter but I will not attempt to bend the screen in two directions. You would need either a giant vacuam former or shape one out of a mouldable material, very dificult indeed. I would take the verticle pipes off and replace them with straight ones.
Third, the material you use can help to make the finishing much easier. If you intend to make a flat screen you can either make a screen from ridgid material or even make one from fabric and then paint it. Yes you can paint fabric and make it look very good. Start with the best quality blackout material as you can find. Build your screen and then spray it just as you would a ridgid material. I have even sprayed interior padded vynil in a show car. I added a flex agent to the paint and you would never even know it had been painted. It looked and felt like factory. It is flexible and soft but very durable. I would also suggest to purchase an inexpensive HVLP gun to do the spraying, that way you can set the gun to create a nice wide spray pattern and regulate the fluid fow and success will be much easier to attain.
For both torus and flat rigid screen, I would highly recommend using MDF. This is a rigid board that is very flat and can be painted to look like glass. For a torus, I would build a basic frame then screw the MDF into it from the front along the edges starting in the middle. I would use 3/8 or 1/4 for a torus but if it is flat you can use 3/4 inch and you don't even have to build a frame. Just remember to paint the back side too or it will warp. For those of you who have larger screens you can buy MDF in over size sheets. For about 60.00 canadian you can buy a 5 by 9 foot sheet. In some areas you can even buy 10 foot long sheets. These will have to be ordered though. I suggest that you prime the MDF with something like Kilz, then sand it to a silky smooth finish with 320 grit paper. Now you are ready for your white base coat. With the right material and practise you can spray a screen that will look very nice and be almost invisible. remember to thin your paint to the point that when you raise the stir stick out of the paint, you see the liquid dropping off the stick nearly in rapid drops and not running like honey. This will ensure that the finish will not have orange peel and will settle nice and flat.
I hope some of this info. will help
I will keep you all posted as I begin to build my screens with pics and proceedure.

Looking forward to your results.

Is there an ideal curvature for a torus screeen at any given screen width and throw distance? I have an XG with a 96 inch wide screen. I will be creating a torus curved in only one plane.

Larry the reason I went with the brush as big as the screen is tall is, because it got me the closest I could get to a invisible screen. There are a few flaws because the seam is not perfect, that's what happens when you can not come up with a complete sheet of material that is 7'X12". I'm the only one that can see the flaws and that is only when there is a uniform image of the same color. This screen looks better then some of the manufacturer's screens. I came about the brush idea because I could not get a more uniform finish trying everything else. Now if I had someone that sparyed show cars for a living, then I probably get a super finish. I may try hiring a professional, but for us DIY'ers spraying a suface as big as our screens with a 4+ gain paint that shows off any (and I mean any) variation, a perfect screen is just not going to happen.

Deron.

I would love to see that huge image on your wall. I know what you mean by no one notices but you, I have to deal with my own sensitivities to my work in progress and remind myself to just enjoy the movie. A commercial screen that size would cost a fortune I imagine.

Thanks for the advice. I know nothing about torus screens at this time. I viewed a very expensive one at premier audio video last week and it apeared to be a cylinder style curve. I am going back there and will take a closer look. It also had fully motorized blanking and looked about 10 to 11 feet wide. They were showing it with a 45,000.00 Runco DLP. Aside from the screen size, I still think my XG throws a better picture. You couldn't watch this picture any closer than 12 feet without seeing pixels. It was quite soft as well. This would definatly be a waste of 45000.00 for anyone imo. I will be doing some experimenting in the near future and share my results.

A cylinder style is not a torus and will give bad results with focus at the edges no mattter what and the middle and edges will have odd hotspotting compared to the flat top and bottom if you use gain. Plus either you'll get the flat part to focus or the curved edges but not both. Imagine a windows taskbar 6" or whatever out of focus at the ends or in the middle. Yuk!

The torus curve gives no gain by itself btw. In other words white torus is pointless unless you just want to create a flight simulator cockpit window effect. The purpose of the curves is to remedy falloff of gain on the edges of high gain materials and focus the gain to you so that the whole screen becomes one big even hotspot.

To calculate the optimum curve take a piece of string and fix it where your head would be when sitting in your premium centered seating area. Estimate where you want the center of the screen to be depth wise and move the string to where the edges would be and measure the difference of depth all around. (This is very simplified and just gets you a rough idea.) Pj mount position determines the angle the screen would reflect back to the seat (like a mirror) so you would want to figure that angle the screen would be tilted too, if any, somehow. Plus it's likely you'll want the focus two or three seats wide rather than just for one seat so then give it a wider curve. If you aren't using a set of lenses specified to handle a full torus then a torus lite with less curve is better than the full curve so you can still maintain decent focus around the edges. Half the curve or so for lite, which also gives a wider optimum seating area before falloff.

You get the basic idea right?

Play away, I know nobody is listening and we all tend to do what we want to do no matter if someone warns us it's wrong or wont work well anyway. I'm just telling you what to expect.

Troy

Troy, Thanks for the info. I agree with you about the cylindrical "torus" configuration and the string idea, although I was considering a more complicated proceedure to calculate the curvature.
I was considering measuring distance to screen from the back center of the projector, then creating an arc about 12 inches long in that plane to follow with the string while creating the screen arch at the other end of the string. This would probably produce a similar "lite torus" as you described and have at least some relevence to the focal length of the lenses but doing this now may not be relevant based on your assertions.

Larry

Troy I going to disagree with you, my screen has real good focus, it's has a 18' radius, which is a real good curve, text from a desktop looks good anywhere on the screen. As for hotspotting with my 4+ gain screen it's just not there, sure you can put up a all white window and see it, but during a movie you can not see it.

Let me add that a low gain curved screen will tend to wash itself out.

Yeah I did pretty much what you said, take a string from where my seating position would be and draw a arc.

I tilted the screen after setting it up, just tilt away till it's brightest towards the center.

With the radical gain and curve I have, seating is good for about three wide, it falls off very quickly after that.

Deron.

One thing I wanted to add is, as you move away from the highest gain seating area, screen defects go away. Low gain screens are very easy to make, you can put the paint on anywhich way and it will look good, the more gain you try to get the more problems you have as the screen has to be closer to perfect.

Deron.

A couple of things that need to be addressed. First Larry, you have or want a horizontal curved screen not a Torus or Torus lite. A Torus has two curvatures. A horizontal curve screen will not give you perfect uniformity, but can be an easier solution as Deron can attest. Second, the string method will produce to deep of a radius for most people and for getting good focus. I started a thread in the archives that has a bunch of members screen curves. Third, the washout effect with a low gain Torus is an old wives tale until I see some actual data. VDC has multiple white Torus screens. If washout was a problem, then they probably wouldn't use them.

Allright I'm going to have to try a curved (non torus) now too I guess, just to see for myself.
But no way will I make it low gain or white. Once you've gone UHG silver (aluminum or whatever) and seen a beautiful projected image in the daylight with the windows open and standard overhead lights on, and things like running contrast in the teens with full light control, and better beam spot size and therefore sharper higher res performance because you're driving the tubes so low, and no burn in worries anymore, anything else sounds (and looks) much less attractive.

All screens have their place, just not in my home.

Troy

Ericglo

Washout with a low gain Torus just seems obvious to me, if you get pretty much a full brightness image at almost a 90 degree viewing angle, that same light you see is going effect the image on the screen.

Then of course I try to sell everyone on a "Full On Black Velvet Theater"

Deron.