Can Rotary And Coil Waste Stamps Be Id'd Using A Stereo Microscope?

I have a handy Amscope that I use for finding doubling on Lincoln cents and taking pictures of insects.

Has anyone done a study on what coil waste stamps and rotary press stamps look like under 20x and 40x magnification? Do they look the same as flat press?

I found a bunch of plate variations for the Scott #300 after reading the Johl book. Little dots and lines in weird places show up randomly. How come the #300 doesn't have more variations other than the coil?

U.S. Scott # 300 is a flat plate printed stamp.

A stereo microscope might be able to more easily distinguish offset vs. engraved printings, assuming you can't just tell those by eye.

I just looked at a Scott #405 flat plate vs. a Scott #543 rotary and there are noticeable differences under 20x magnification. For instance, the ink along the outer border on the rotary press tends to leak outside the edge a bit, whereas on the flat plate, it's more flush. Also, the lattice pattern behind Washington's head is much more honeycomb-like on the rotary, but on the flat plate, it's more shaded in and harder to see the little holes.

Yes, but there are also rotary stamps which have too much ink and so you can't see the difference always.

Early rotary press stamps typically have excess ink, usually due to poor plate wiping (almost like a film over the entire stamp). Those sorts of artifacts can be seen without a microscope (or even magnifying glass) though.

The quick answer is that the Rotaries are larger than the Flat Plates.