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josh8140   

Can anyone clarify if there would be any visual advantages/disadvantages to using MDF, melamine or plywood as a screen material.

I will be using a base primer coat and 5 coats of the black widow mix so would there be any noticeable difference depending on which material I use? I would think they would end up looking the same after this many coats of paint but some forums have said melamine can cause hot spots, the plywood texture may show, etc.

I'm not sure if it matters but I will be using a BenQ w1090 at 2.8m so around a 90" screen.

Thank you for any help.

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Quark   

I definitely wouldn't use plywood - the grain is likely to be visible even if you use marine grade (the smoothest). Not sure how you would go getting paint adhesion and a consistent finish on melamine - expect MDF is your best bet.

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Posted (edited)

hmm is there a reason you want a big piece of board? mobility maybe? a wall would be just as good.

the other thing with that pj to consider is the colour of your ceiling, wall behind the screen and other walls.. in that order.

Edited by hopefullguy

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josh8140   
Posted (edited)

Thanks, that's true, i'll go for MDF which also works out the cheapest. Bunnings stocks 3mm to 16mm thickness sheets so I might get the 3mm to keep the weight down. It does bend a fair bit though so would that will affect the paint?

I'm currently renting so I'm looking to build a board and stand I can take from house to house. The back wall is white but sides are grey.

Edited by josh8140

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Quark   

If you use 3mm you'll probably need a decent frame with multiple bracing to reinforce it.

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Posted (edited)

agree.. 3mm is very thin so a frame would be needed. but having made 2 screens my self portability using material is a problem as easily damaged.. a board wont suffer this.

just an idea about the wood. as you are going to paint it anyway when you go to bunnings and look at the mdf area you will see what is called "cover sheets" these are used on the top and bottom stack of sheeting to keep the main pieces undamaged in transit. if you ask they normally sell them for $10.. it is the same as the good mdf sheets just a little dirty. could save some money this way.

i would think 9mm would be ok i dont think 3mm will be worth the trouble

Edited by hopefullguy

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josh8140   

Awesome! Cover sheets sound like a smart idea. I'll go for the 9mm so hopefully it lasts longer. I think I'll prime the edges too in case any liquid ever gets spilt on it.

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CAVX   

If DIYing a screen, try and track down "FOAMEX".  I used this for while unpainted and it generally was pretty good.  

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Owen   

Is there a reason why you want to DIY? Chinese projector screens are really cheap and will almost certainly be better than what you are proposing.

The fixed vinyl screens have a super smooth surface and will be much better and weigh much less that a sheet of board.

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josh8140   

Yeah I have sourced a PVC foam sheet which I'll try painting, it should be super smooth! I haven't been able to find any cheap screens with a grey tint like black widow. I may buy a cheap white one to compare when I'm done though but from what I've read the black widow paint will have much nicer blacks and contrast compared to a white screen.

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Owen   

A grey screen will have a lower gain then white and provide a dimmer picture, but since black and white are dimmed by the same amount contrast is unaffected.

I have never seen PVC foam that I would call smooth, and even it there is you will need to spray the paint on in a dust free environment and be talented with a spray gun  to have any chance of getting a surface any where near as smooth as a vinyl screen material, its REALLY smooth.

The cheap Chinese fixed screens typically have no gain and I have seen grey ones with gains below 1.

There is a link to some grey vinyl material for cheap. Don't know how smooth it is.

http://roundupreviewsau.com/au/gray-projector-screen-material

http://www.ebay.com.au/itm/Carl-s-FlexiGray-16-9-71x126-Projector-Screen-Material-High-Contrast-Gray-/231018415694?hash=item35c9c5464e:g:lcgAAMXQysxR8CxV

 

If you want a screen for a non dark room that actually works you need a high tech ambient light rejecting screen, they are angular reflective, complicated to maufacture and normally VERY expensive, although small sizes have been available for not too much in the past.

Even then you need to understand how they work and manage their limitations. They typically only reject light coming from above or below, not from the sides or from the projector end of the room.

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josh8140   

Cheers for the links Owen, I'm going to pickup some of the material so I can do a comparison to the paint.

I'm aware using a low nap roller is the cheapest way to get an almost smooth paint surface but if it doesn't come out smooth enough I'll be renting a sprayer and painting the other side. The PVC is insanely smooth which is why it's used for sign printing so I don't think that will be an issue.

The black widow mix is a little different to grey as it uses aluminum to tint it which gives it better whites, blacks and dynamic range. There's some good info on it here:

https://en.wikipedia.org/wiki/Black_Widow_(paint_mix)#A_very_brief_history_of_DIY_painted_screens_and_some_of_the_more_popular_methods_and_mindsets

I've got a very dark room for the projector so I'm hoping it looks amazing.

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Owen   

Don't get sucked in mate, no screen can improve contrast in a dark room, its simply not possible. The screen reflects light equally for white and black so the ratio of black to white (contrast ratio) is ALWAYS the same. The amount of light that is reflecting is determined by the screen gain, low (negative) gain gives a dimmer picture for both black and white. Higher (positive) gain screens give a brighter picture for both black and white.

There is no way to reflect low light levels (projected black) and high light levels (projected white) differently.

If you really want to improve ANSI contrast you need to reduce or elimiante light coloured surfaces in the viewing environment that will reflect light back at the screen and degrade contrast in brighter scenes, that means black walls, ceiling, floor and furnishings. This makes a MUCH greater deference than any screen can.

If you have a blacked out and dark room a white screen (gain of 1) is normally the go because it will have the best screen uniformity. Even the very expensive angular reflective screens are pointless in a black out and dark room, and slightly degrade picture quality compared to a white screen.

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josh8140   

Thanks for the explanation, I had the same thoughts but I'm not sure if the aluminum somehow improves whites. Either way it should still be a good mix as it's supposed to do good with ambient light and dark rooms so it sounds like a good all rounder.

https://simplehomecinema.com/2014/10/12/how-to-build-a-300-screen-that-performs-like-a-2000-one/

Wish I could paint my walls darker lol but I'm renting at the moment.

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Owen   

Aluminium typically reflects more light than white, it has a gain of more than one. This will make whites brighter, BUT it will make blacks greyer (brighter) by exactly the same amount. Is that what you want?

For a not dark room extra gain is useful, but for a dark room its counter productive.

 

If you are renting and cant paint the room black, create an alcove out of black velvet stretched over a home made frame that is free standing and doesn't damage the room surfaces in any way. The "tent" is relatively close fitting and extends out about a meter from the screen at top and both sides. This blocks much of the light from the screen from shinning onto the ceiling and walls close to the screen and lighting them up. Its really effective and makes a very notice improvement to contrast in bright scenes, plus it keeps the area in your peripheral vision black or very dark which is very helpful for immersion

If the floor is not a dark colour a dark coloured rug or more black velvet covers that angle. A dark curtain can be used to cover the wall opposite the screen, supported by a floor standing frame if you cant hang it on the wal.l

This approach works better than a multi thousand dollar angular reflective screen and eats a painted screen.

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josh8140   

Interesting I haven't seen that done before, I will look into it if I'm not happy with the contrast. The aluminum has a grey tint too so I'm not sure if it's going to make things brighter or darker. Hopefully it defies the laws of refraction and I get darker blacks and lighter whites lol.

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As long as the plywood is sanded super smooth and primed+smoothed, it'll be as smooth as you make it.

Melamine is glossy/hotspot-y when used unpainted, but coating it with flat/matte paint or primer will make it just as flat/matte/non-hotspotty as any other flat/matte surface.

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josh8140   

True, I ended up buying the PVC foam and painting it with 4 coats of black widow with a low nap roller. Even with a low nap roller there's a texture and I tried sanding the primer but the scratched texture looks even worse. The guy at the paint shop said there's no point sanding primer with higher than 240 grit as rolling the paint will always leave a texture. The black widow paint seems to hotspot with a torch so it will be interesting to see if it does with the projector.

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Hey guys,

 

Since I got fed up with having to explain to people how to mix cinema paint over the years, I am selling pre-mixed versions of N7.5 darkness starting from today if anyone is interested. The first batches are limited to 10litres at this point and there's a lead-time of 1 to 2 weeks dependent on stock but things will speed up considerably over the next month. Direct your friends to it, especially if you are just as tired of explaining as I have become.

 

https://wordpress.com/page/simplehomecinema.com/1187

 

http://www.ebay.com.au/itm/122690754801?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

 

Thanks,

 

Roland

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