Mary K, I have a bit of wood-plug experience in my woody. I have counted 600 so far, but got tired of counting. I make all of my plugs out of birch or maple 1/2 inch dowel pins. I cut them about an 1/8th of an inch longer than the depth of the hole, and glue them in with titebond II.
The mistake I made when I started on my plugs, was to sand them down flush while the glue was still wet. This smears the glue into the grain of the adjoining wood, changing it's color or preventing stain from entering the glue area, resulting in a lighter situation.
If you want to eliminate the dark ring around your pre-made plugs, you might want to cut the plugs out of black walnut, since you are using a plug cutter. Increase the speed of the drill press, drill the plugs more slowly, snap them out of the waste piece with a screwdriver and have at it again.
Roly.......not the words of an expert, just from a trial and error kind of guy
