Certainly looks like it could have been grease or oil that stuck to the blank before getting plated.
I can't imagine copper would bond very well to oil or grease.
Here is a link to a thread about the plating process and showing the tumblers (45 RPM) and terms that are used by the producer of the Lincoln planchets. The video is pretty neat to watch if you've never seen it before. It's mesmerizing.
Be sure to scroll down to the third post to get to the real the video.
http://goccf.com/t/350002
I can't imagine copper would bond very well to oil or grease.
Here is a link to a thread about the plating process and showing the tumblers (45 RPM) and terms that are used by the producer of the Lincoln planchets. The video is pretty neat to watch if you've never seen it before. It's mesmerizing.
Be sure to scroll down to the third post to get to the real the video.
http://goccf.com/t/350002
Words of encouragement are one of the major food groups.
We need to consume them regularly to thrive and grow.
We need to consume them regularly to thrive and grow.
























