Originally Posted by DonRSD
My wall is a light grey color. Doesn't really show good blacks during the day.
I have an Epson 2045 (from Best Buy). We watch 3D & I would like that option for when I need it.
How do I decide what type of black I need or the gain I need?
I will paint a 120" screen on the wall.....but where did the OP buy that $8 panel from? Would rather NOT paint the wall.
Im a total newb with projectors & screens, so Im sorry for the non-expert questions
The gain you'll need is found by knowing your projector and screen-size and then compensating for things like 3D use and the likelihood that you prefer using Eco-lamp with that projector whenever possible since it can be louder than some.
Your projector starts around 1100lm/1600lumens (Eco/Full) in the dimmer more accurate settings and has a great ability for bright 3D.
Dividing that ~1100lumen quieter brightness by a 120" size (almost 43square-feet) gives a still super-bright 25.6ftL on a 1.0gain surface.
For reference, a good commercial theatre runs around 14ftL and your grey wall likely puts you at 15ftL-18ftL right now when you are using Eco-Lamp.
Aiming for the dimmest mode to hit 18-20ftL will keep you about as bright as you are right now and give a good amount of headroom for 3D and lamp-aging.
That'd be a 0.7gain surface at 120" or a lower gain at a smaller size.
With the gain being on the lower side it's easier to use a darker grey and still have the paint turn out smooth and clear when projected on..the bigger you spread the gain (going higher) and the color (going darker) the more likely you are to see problems happen even from tiny little flaws in the surface or paintjob.
Choosing a color that's natural gain is about half that of your screen's peak-gain gives a really clean image that fights light more subtly.
Choosing a darker one around 1/3 of the screen's peak-gain can give a nice balance of light-fighting and still decent odds of it looking clean.
A darker 1/5 or more surface gets really aggressive against light, but drastically increases the odds of showing texture if the paintjob didn't go well and it'll dim more noticeably if you view from the side.
Aiming for a color with a natural gain/reflectivity around 0.25-0.35 should be great for a 0.7gain screen at 120" and the screen will look a decent ways darker-colored than your wall.
I (the OP) bought the panel from HomeDepot, but it's only 4'x8' which limits it to a normal 98"-100" screen OR a 110" screen with the top/bottom 3inches cropped off. Finding a panel for a full 120" can be more difficult and generally pushes the price closer to $80-150....unless you want to build a screen using a 4.5x8 or 5x8 sheetrock panel (which will be cheap but more brittle, obviously).
Do you think you'd prefer the bigger 120" screen at a higher cost or requiring more careful moving or using the wall?
Or would you prefer shrinking down closer to 100" and possibly moving the seats forward a foot or two?
For these different sizes using that 1100+lumen projector I would aim for:
120", 0.7gain-peak and 0.25-0.35gain-color
110", 0.6gain-peak and 0.20-0.30gain-color
98", 0.5gain-peak and 0.16-0.25gain-color
Using the rolling instructions on the very first post in this thread, I would buy a gallon of either Glidden or ColorPlace(walmart brand) flat interior tinted "Seal Grey" and pour about 1quart into a separate container to mix with about 8oz of water and use that for the first coat..let it dry a few hours and then shine a light sideways onto it to check if any areas could use a quick sanding.
Then I would buy a quart can of either RalphLauren metallic silver "untinted" (from HomeDepot) OR a quart can of Disney/Glidden magnificent metallic "untinted" (from Walmart) and have the store shake it up but not add any tint.
Then in a separate container I'd mix the whole can of metallic together with 14oz-15oz of "Seal Grey" from the gallon container (NOT anything that's been thinned with water)..and use the same first-post rolling instructions to roll a coat using this mix.
Watch the video below the instructions too if possible. I like to make sure the roller has a good amount of paint on it for each row because I use practically no pressure while painting even if the surface is up on a wall. Even while loading the roller with paint I never pressure it into the pan..it's all just letting the roller do the work. ..'cause I'm lazy...and it helps avoid roller-marks and texture.
That was a tower of text, feel free to ask questions.