Hi all Recent posts in this thread have missed one point... The smoothness of a follower board (dummy frame) allows air to be moved by convection where a much lower temperature difference occurs. I have built experimental hives with walls that are a sandwich consisting of 6 mm ply open single bee space 6 mm ply remarkable air convection currents are set up by very small amounts of insolation because the outermost wall is so thin. Best Regards & 73s, Dave Cushman... G8MZY Beekeeping & Bee Breeding Website Email: [log in to unmask] or [log in to unmask] http://website.lineone.net/~dave.cushman & http://www.dave-cushman.net :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::