Re: Photo: UP Boxcar 74227
While we're on the subject of sealing, someone asked about the taping of doors last week. I didn't immediately think of duct tape (duck tape), which was actually a WWII invention, but it turns out similar tapes had been available for many years ("by the 1910s").
For modeling purposes, I suppose the only reason we'd care is for the typical color(s) of the tape. I've thought of white Prismacolor pencil, which performs ok on models to simulate graffiti, the fifties kind made with chalk.
In wheat country, that tape and its residue used to be very common on boxcar doors during and after harvest season.