If you want to retain your plant identification, we recommend using our marking products. The Black Marking Pencil  or Mechanical Grease Pencil is best for the zinc nameplates. For best results, write on the nameplate, then set it in the sun for a day. The marking will "bake" onto the nameplate and should last for years.  The DecoColor Marker is the best we've found for our copper nameplates. Markings last 2-3 years before beginning to fade. Once the markings are on the nameplates, they are very difficult to remove. If you know that you want to re-use your nameplates, you can use a Sharpie marker which will fade within a month or two. Don't forget that you can mark the back side of your nameplates as well!