Few household items are as treasured as heirloom glassware that has been passed down from generation to generation. Newer pieces can also be beautiful and expensive. However, delicate glass items can develop hairline cracks over time. When this happens, address it quickly; the longer you wait, the deeper and longer the crack will become, and the more difficult the repair job will be.
Apply non-toxic, clear epoxy to the crack. Use a cotton swab to work the material into the crack. Keep the epoxy in the crack, not off the sides of the crack, as this will just require more sanding in the next step. Wait overnight for the epoxy to dry.
Dip the 800-grit wet/dry sandpaper in water and sand the crack with quick, short strokes. You only need to sand for a handful of strokes before moving on to the 900- and 1000-grit paper. The goal is to buff the crack quickly with a higher and higher grit. If the piece is older, you may want to sand the entire piece with the 1000-grit sandpaper after you have repaired the crack for a uniform appearance.
Apply a coat of silver polish to the entire glass with a clean cotton cloth. Let the polish sit for a couple of minutes before buffing with a clean cloth.