US 'Gum blankets' were last used in Vietnam. The things are considerably heavier and so yes, condensation is a concern. They also stay draped and don't flap around like the modern coated nylon affairs.
WARNING & DISCLAIMER:
SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted
on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please
review the full WARNING & DISCLAIMER about information on this
site.