I just ordered a couple of new screens with 230 count white mesh. I have been using 180 count white mesh. I'm using Ulano TZ with a homemade exposure box. Using vellum, with the 180 count screens, it takes around 5 1/2 minutes (yeah, yeah, I know it could be a lot quicker with other bulbs, but that's beside the point).
Now here's the question:
How much longer or shorter (thereabouts) will the exposure time be with the new mesh?
Mind you, the 230 count screens left Los Angeles travelling at 55 mph, and the 180 count screens left Reykjavik travelling at 25 k/s.