Light impressions, University Supplies, and Hollinger sell archival photo pens that I use when writing on typically non-porus surfaces that need a thick line (mylar, poly, etc). I don't know how they'll hold up to the water test, but it may be worth a try. For really fine stuff, I had used Micron pens, but my new favorite is the Millennium Pen. It's a felt-tip, acid free, waterproof, light fast, fade proof, non-bleeding made by Kuretake Co. Ltd (I have it sitting in front of me). It comes in lots of widths, but I really like the 005 (I think that's .5 mm). Typically though, all of our lables have no risk of contact with other artifacts because of bags, label covers, or other buffers. Also, the Museum Tech before me used primarily Sharpie or Micron pens. -Elizabeth Cahill Elizabeth Cahill Museum Technician, Cultural Resources Great Smoky Mountains National Park 107 Park Headquarters Road, Gatlinburg TN 37738 ph: 865.430.0340 fx: 865.436.1220 ========================================================= Important Subscriber Information: The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes). If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).