Posted By:
Phil MichelIf compelled to erase...I learned this from a paper conservator.
Use a fine grater to make tiny crumbles from your art eraser. Pile the crumbles onto the card and use the flat side of the eraser to roll the crumbles around the surface of the card. Only apply as much pressure as needed. Little by little you'll see the crumbles turning darker as they pick up the pencil and other surface dirt.
The indirect rubbing reduces the chance that you'll abrade the surface of the paper, overheat the surface with friction (causing a sheen), or accidentally catch the edge of the card while rubbing. Use a camel's hair brush or new paintbrush to clean off the crumbles when done.
Make sure to clean your grater when done or your nachos won't taste so good next time.
=Phil