I had to replace the fabric strips that made the light seal for my Graphic 23 roll back on my 4x5 Pacemaker. I used some 1mm thick felt material camera light trap strips I had on hand. With film back on and dark slide pulled, I set the camera in the sun for a while. Then I advanced frame and shot a few test frames. The first frame after sitting in the sun is fogged badly. The test frames seem ok. I think the recommended light trap material is black velvet. Maybe I should use the velvet because it is fuzzier and may crush for a better seal? Anyone had good experience with replacing the material for this light trap? I am kind of desperate because I am heading to Tucson next week. Thanks!