Okay I went ahead and did something that most would think would be nuts but the hot spotting in the center of the screen was bothering me. Also, there was defiately some color shifting present as well.
For example, I have my Windows XP background color set to grey and you could clearly see in the center of the screen the affect of the hotspotting causing the colors to be an off grey near the center.
I went to HD and purchased a quard of UPW Flat interior. Had the guy shake up the paint really well and then got some very fine foam rollers so that when I applied the paint to the laminate it would be as smooth as possible.
I first cleaned the laminate with 91 percent isoproply alchohol to make sure there were no contamintents on the surface. I then applied 2 coats of UPW to the laminate waiting a few hours in between.
The results: My hot spotting issue is completely gone!! My grey XP background screen is perfectly grey without the other issues I was having before. Color and brightness uniformity appears excellent.
Regarding how the image quality looks, I think that I can say that with the DW laminate, the image perhaps was a bit smoother and more highly resolved. Also, the picture seemed to have more "punch" to it than now.
It seems in the DIY screen world there is no perfect answer. The DW laminate material seems to offer a better quality image/brighter and better resolved but with a slight hotspotting /color uniformity issue in my case. The Behr UPW flat applied to the DW laminate cures the HS/CU issues but doesn't have quite the PC the laminate offers so thats where I am at now!!
The only thing that I can assume is that with the UPW applied I now have basically a matte white unity or slightly under unity gain screen where with the DW material it was closer to a 1.3 gain screen. Also, the application of the UPW is not as smooth as with the laminate so this can be the cause of the image not being has highly resolved looking but this is all mere speculation.
Originally Posted by Clarence
Yes, I can see a slight warmspot in the center on the solid white test pattern, not during normal content.
I'd suspect the effect might be even more noticeable on your screen since your projector is closer (92" on yours vs 115" on mine).
My tubes have about 8500 hours on them now... still running amazingly strong... about 2000 hours of 1080p last year. I've got a spare set of tubes ready and waiting in case these ever get worn.
Ken W did another great calibration on it a couple of weeks ago.