How many square inches would be covered by a pound of hot-melt adhesive?
The adhesive bead thickness varies. For a bead of adhesive for components (zippers), it might be 1 mm in diameter or more, but for a wide coverage it would be smaller–maybe 250 microns in diameter, and it would be put on in swirls or zig-zags instead of straight lines. Density is near enough to water that I would use that, since the main assumption is the thickness of the bead. 1 lb of 500 micron bead would go about 2.3 km according to my calculations (which should be verified by the students). Converting that to area depends on how they apply it.
