Tiddler, man what a thread you have as well! I have questions regarding substrate, paint and topcoat that you might help me out on as you're well aware I've done tons of reading and research before asking/posting my question.
Here's my story, and I am sticking to it...
The projector will be driven solely by a home built high-end HTPC (Asus P5B Deluxe motherboard, Intel e4300 Core2Duo overclocked to 3.4ghz, Zalman cooler, 2gb of OCZ DDR2 Ram, 74gb WD Raptor 10,000rpm main drive, 1000gb Maxtor 7200rpm storage, Asus 16x DVD, Diamond ATI X1950Pro 512mb dual DVI output PCI express video card, SoundBlaster Audigy2 ZS Platinum PCI sound card, TwinHam HD Satellite Tuner Receiver PCI card coupled to an 80cm motorized dish with the extremely low noise Invacom Circular+Linear LNB on the roof)
Screen Size = 16:9 92" Diagonal (45"x80") viewable area with a 3 3/4" Triple Black Velvet wrapped boarder from Denver Fabrics (they're local unlike Sy Fabrics).
Projector Model = Brand new (clearence priced at Projector People for $625 delivered) Hitachi PJTX100 (1200 Lumens). FYI: I will upgrade to a brighter 1080p model when they dip into the $1500 to $2000 range (hopefully within two years).
Lighting Condition = Off white eggshell finish painted living room with 9' ceilings and four 3'x6' windows that have white cellular shades then dark red velvet curtains that close over the entire window, dramatic light reduction.
Projector Mount = Most likely sitting on one of the roomy shelves of a room divider/shelf system behind the sofa and can be placed anywhere between 4' to 7' feet from the floor as per your guys recommendations. I could ceiling mount the PJ (projector for us newbies) if an absolute must, but I own a two story condo and running the wires would be difficult and costly since I don't have an attic above me.
Any suggestion or other considerations on any part of my setup is greatly appreciated, but I would love to knock out and begin searching for these items ASAP:
1. What rigid and relatively light substrate should I use in a framed setup that will be attached to the front of my fireplace mantel about the midway point then at the top with brackets coming out from my wall to compensate for the 4" mantel protrusion (not above my mantel as the screen would be to high).
2. What is the best brand, base, color and finish paint I should use to coat the recommended substrate in order to achieve the most neutral gray with this setup.
3. What is the best topcoat I should use for recommended substrate and paint?
I will then post all my results and photos comparing a projected HD image on the uncoated (hopefully pure white) substrate to an image of the two most recommended neutral grays in a quadrant format with two of the quadrants with the grays with a matte finish polyurethane topcoat as well. Photos will be taking with a 6 mega pixel camera on manual settings atop a tripod from various angles in several lighting conditions. See, I read the entirety of several threads before making my post... hours and hours I tell you, hours!
I want to help out as much as possible, because you all have helped me tremendously, plus I am the youngest of eleven and sure enough, they're all going to want an HTPC Home Theater after I am done! I've only saved them about 3 months of work and research, believe me when I say research...