Hello Quin, There has been much discussion on Conch-L over the past months on many different methods for cleaning shells, and you can find a wealth of information by going through the Conch-L archives. However, just to give you a brief direct answer to the points you mentioned: Chlorox bleach - there are some mixed feelings on this, particularly regarding certain groups of shells, like abalones (Haliotis), cowries (Cypraea) and shells with mother of pearl interiors. Nevertheless, chlorine bleach remains the single most widely used substance for cleaning shells. It does a good job of removing any kind of organic matter, which includes algae, periostracum, and bits of tissue left inside the shell. It does not do a good job on inorganic encrustations like barnacles, coral, worm tubes, etc. Still, even these may have some organic component, and the bleach may therefore soften or loosen them somewhat, so they can be picked off more easily. I have cleaned many thousands of shells in Chlorox, and have not noticed any deterioration of color, even on long exposure. During the discussions though, a couple of people did mention specific instances where they believe some color loss did occur. Varnish - please, no! A varnished shell is a ruined shell. You mention preserving the "hardness" of the shells. That is not necessary. The hardness will endure, unless the shells are stored in very damp or humid conditions. In that case, molds, acids, and other problems also come into play. The greatest threat to shell color is sunlight. If shells are stored in a cool (or at least not excessively hot), dry place, away from direct sunlight, they can remain fresh-looking for many years. Toothpaste - this is a new one on me. You specifically mentioned fluoride toothpaste. If you are talking about improving the hardness of the shell, the same way fluoride improves the hardness of tooth enamel, I seriously doubt that this would happen, and as I said, it is not necessary anyway. Hope this helps a bit. Paul Monfils