An important aspect of benchmark hunting and recovery is to take a closeup photograph of the disk. Often a disk is buried under leaves, dead plants, and perhaps some dirt. You will want to clean it up a bit for a picture. Bring a rag, or a pack of pre-moistened wiping cloths or a few paper napkins. Those will clean much more efficiently than your fingers. It is not necessary to polish the disk. Just enough cleaning to be able to read all the inscriptions will be sufficient.