heart that is made up of many small pieces of glass
Tracy, did you make it yourself ? If so you could use a good-quality
two pack epoxy clear casting resin to encapsulate it with.
If it’s an old piece however it will already have been "glued"
together with something and if that’s breaking down you’ll need to
remove all the loose stuff before you encapsulate it. If you need to
remove the epoxy later, whatever agent you use will probably also
destroy the “old” matrix, and hence the mosaic.