Hi,

For years now I have drilled 2 small (1/8^th inch or so) holes in the bottom of any boxcar, reefer or tank car to let anything vent out.

From my British modelling days 30 years ago I have a bogie open wagon (aka a gondola) plastic kit that had its lead weights glued on the bottom with contact adhesive (Evo-Stick) which now has a banana shaped floor, even though it was completely in the open and not sealed shut.

These days I’m a fan of using canopy glue to hold weights in place, it’s just slow to set.

Stan Agar in NZ