The Geological Survey of Alabama has several fossil shells that were probably coated with shellac in the 1930's or 1940's. By 1990, the shellac had yellowed, darkened, cracked, and peeled, ruining most of the fragile specimens. Because some of the fossils were collected at sites that are now permanently underwater, the loss cannot be repaired by collecting additional specimens. I do not recommend the use of shellac for preserving shells. Andrew K. Rindsberg Geological Survey of Alabama Tuscaloosa, Alabama, USA