A word on the "gain" of the Parkland material. I may have posted similar information many months ago, but do have a bit more to say now.
I've seen multiple posts in this thread and others that have stated that the gain off of the Parkland material is >1.0, with claims going as high as 1.3-1.4 for the shiny side.
I have used this material for about 18 months now. I have compared some leftover pieces to other screens, and I have carried my portable screens to other houses and propped up them up right across other screens in a sort of split-screen arrangement.
My findings have been quite consistent from test to test. In what I consider to be the most significant comparisons, split screens against Draper and Da-Lite standard 1.0 matte screens, both the shiny and matte sides of the Parkland were ever so slightly dimmer, so close that it took a little time to be sure of ourselves. Vs 1.3 gain screens, it was easy to see that it was less bright, but it was still good.
My estimate of the screen gain of the Parkland material is 0.95 .
Used with 1000 to 1400 lumen projectors, neither the matte or shiny side showed any hotspots.
As with other 1.0-type screens, the viewing angle is very wide, with no noticable dropoff in brightness at even very sharp angles.
Colors were quite good. This is very close to a pure white.
The material is quite solid & opaque. There is no noticable loss of brightness or image sharpness due to light bleeding through the material. I can see no reason to be concerned about the color or reflectivity of the surface behind the Parkland.