Before engraving has started, the edges have been smoothed off so they
won't catch the ink or tear the paper.
No marks have been made yet. The plates come polished, but I smooth the surface out even more before I start engraving.
The edges are worked with a file to round them, then smoothed out with fine sandpaper (called emory) so it won't cut the paper when run through the press.
This plate is made of 16 gauge (.064 inches) copper, my preferred metal to work on, called "Engravers copper." If the plate is too thick it might cut the paper like a die would.The copper has a lustrous surface that is easy on the eyes and cuts cleanly.
If your burin or graver tool is properly sharpened, a spiral of copper peels off as you are engraving, like an apple peel. Your tool can leave a line of varying depths and widths.
There are also other tools that produce different effects.