This is the part I would spend more time on if I had it to do again... and indeed, I'm less than satisfied with the results, so I probably *will*
do it again!
My fist instinct was to use the wall behind the frame as a projection surface, but I was unhappy with both the color (really made the whites looks dingy) and texture (it's a typical orange-peel drywall paint job, but anytime there was a solid color it would really stand out). I didn't want to deal with smoothing the wall, so I opted to go with either a fabric or a painted/mounted substrate.
For starters, I got some test swatches from both Carl's and Elite. I really had high hopes for the Carl's ARL, due to some of the positive reviews I'd read. When I tried it out though, it was evident even from the 8x11 sample that it wasn't going to work for my room. On the plus side, when viewed on axis it was great... blacks were deeper, the image "popped", very impressive. However, the viewing cone was just too narrow... if you look at the sketch of my room layout in the first post, you'll see there's quite a bit of off-axis viewing from the counter/bar area, and the drop-off from this angle was just too severe to be watchable. Also, I could tell just from moving the small sample around the screen that there would be hot-spotting.
After evaluating all the samples, my top choices as far as fabric were the CineGray (which had nice, deep blacks but seemed to push the whites a bit blue) and the FlexiGray (which was very neutral, but didn't reinforce the blacks quite as much). However, since I would be mounting to a thin frame or substrate anyway, and since I have quite a bit of latex paint around the house, I decided to experiment.
For a painting surface, I decided to go with the Parkland Plastics Plas-Tex.
I know that this material is pretty much deprecated as a ready-made projection surface since they changed the texture, but after evaluating it firsthand at Lowe's I decided it met my needs, since 1) I would be painting over it anyway, 2) the smooth side was *much* more low-profile than my existing wall surface, 3) the 4x8 sheet would more than accommodate my screen size, 5) it could be rolled & transported easily in my car, 6) it was thin enough to mount easily behind my frame, and 7) it was cheap.
For the painting (again, starting with what I had around the house), I first combined Dunn-Edwards Evershield semi-gloss deep base with some Dunn-Edwards Suprema semi-gloss white, and blended to a shade that approximated the FlexiGray. Those are the results you see here, compared to my wall: did wonders for the blacks, and the image looked great from head-on, but off axis there was an unacceptable sheen.
Then I tried some really low-grade off-brand flat white instead of the semi-gloss; this fixed the reflectivity, but it really made the whites look dirty. The stuff was really thick, so I can imagine there was quite a bit of clay content. Lastly, & what I finally settled on, was the Dunn-Edwards ultra deep gray mixed with Killz 2 Latex flat white primer, roughly matching the FelxiGray in shade. Put on top of a primer coat, this really seemed to do the trick, and honestly I very satisfied with the color for now, it's mostly my paint job that I'm unhappy with. I don't really have a good place for spraying where I am, so I was stuck with rolling, so I do notice some roller-marks when viewing off-axis, particularly on the window side of the screen.
In the future, I think I would go with a single-can solution medium gray, as I think I would have gotten similar results with a lot less work.
Next, since the projection area would be slightly inset in the frame, I applied a 2-inch strip of Carl's black felt tape around the perimeter (less than an inch of this would be visible once the frame was in place, but hopefully it would give a nice sharp border). I left the adhesive backing on at the corners, and then by slipping a sheet of cardboard behind the overlap and cutting corner-to-corner I was able to get a nice clean 45-degree cut that disappeared when applied:
Lastly, I mounted just the screen portion of the project for testing:
Next: Finishing & Final Mounting