The volunteer at the Mesa dig who showed me why you never scrub pottery
Two summers ago I was at a site outside Mesa and kept scrubbing a piece of plain brown pottery with a toothbrush because I thought it looked better clean. A volunteer named Ruth, who had been digging for over 20 years, put her hand on my wrist and said "stop, you're washing off the soot." She showed me how the black marks on the sherd were actually residue from cooking fires, and those marks are what let researchers figure out what the pot was used for. Since then I only dry brush with a soft one and leave anything dark alone until someone who knows more takes a look. I had no idea a clean artifact could actually be a ruined one. Has anyone else had a volunteer or crew lead correct something you were sure you were doing the right way?