I never thought of using these like halftone patterns! What a great idea! Rather than lightfastness, I'd worry that the adhesive would eventually dry up, and the tape would fall off. I use Tombow Mono adhesive, a similar glue tape, and I've encountered a number of types of paper that it will not adhere to. I use it for attaching mementos to my journal, but I wonder if everything will fall off in a few years.