Posted By:
Kevin SaucierA finger rub and/or dirt will usually look much different than a natural tone. Give it a try on beater. Cut one side and try to finger tone it to match the other sides. Not as easy as it sounds but educational and interesting to attempt.
Sure there are exceptions to every rule but the results are not always as obvious as the exaggerated picture above. Many times the toning even on a very clean vintage card can be very subtle...but usually there.
The example I gave is a basic trimming 101 lesson for graders.
Just trying to help!
Kevin