Collectors often don’t understand the difference between the hard and soft paper varieties of the large Banknote issues from the 1870s and 1880s. The National and Continental Banknote companies printed stamps on hard paper. The American Banknote company printed stamps on soft paper. Here is an easy way to tell the difference in the papers. And it’s cheap too!
Using your stamp tongs, hold the stamp firmly in the middle. Take your thumb and slide it gently down the edge of the stamp. You want to bend the stamp slightly, but not enough that you’re going to crease it. Allow the edge of the stamp to glide off your thumb. As it does, the stamp will return to its flat state.
Stamps with hard paper exhibit a clear snapping sound. It’s a strong snap, or cracking sound. You can’t mistake it. Also, as your thumb is bending the stamp slightly, you’ll feel some resistance from the stamp paper. The closest thing I can think of to this sound is to take a sheet of notebook paper. Hold an end in each hand. Bring your hands together so that there is a hump in the middle of the paper. Jerk your hands apart quickly and pull the paper tight. That’s the same kind of snap or cracking sound you’ll hear with the hard paper Banknote issues.
Stamps with soft paper exhibit more of a thumping sound. It’s not as strong or as clear. As your thumb is bending the stamp slightly, the stamp feels softer. If you took a piece of paper towel in your hands and jerked your hands apart as you did with the notebook paper, you’ll notice that the paper towel is a dull, thumping sound.
There are more sophisticated techniques that measure exact paper thickness. The average collector can’t afford these measuring devices. Using your thumb to gently bend the edge of the stamp is effective most of the time. Try it on a couple of examples. The difference is unmistakable once you hear it.