I have thought in the past about whether the fabric "Gortex", which has perforations large enough
to allow water vapor to escape, but too small for liquid water to enter, would be a good winter
venting material for hives, as it would also assist the bees in maintaining cluster temperature by
reducing overall airflow, but might alleviate the condensation problem.
I was given to understand that Gortex is not sold directly to the public, but only to manufacturers
of finished goods.