Are you sure? The 8.34lb per gallon you originally quoted just happens to be the weight of an imperial gallon of water. I suppose it depends on the solvent used for the paint (not sure what it would be in WW2) and the volume the paint would occupy in the gallon v the solvent. Weight of wet paint per gallon = weight of water per gallon seems a bit too coincidental to simple old me. Just noted Robert W has queried it as well.