Round mineral & sapphire glasses are fixed onto the watch by either friction or glue.
Friction fixed glasses have a nylon ring holding it in place. Using an eyeglass look at the side of the glass and look for a white ring (occasionally green of black) between glass and case.
Glued glasses are glued using epoxy resin or UV glue. These are getting rarer as the manufacturers find it cheaper to use the nylon rings
Both methods follow the same steps
- Clean back of watch and open it as you would while changing the battery
- Check battery and change it if needed
- Remove stem and movement
- Place movement in clean airtight box
- Remove old glass trying to keep it as intact as possible.
Nylon rings: using a case back press push the glass from the inside of the watch.
Glued Glasses: Heat the watchcase and glass with a heat gun or boiling water to soften the glue and push it out (if case has stones revert to a case back press as the heat softens the glue of the stones). Using a graver, knife or screwdriver remove any old glue.
- Check old nylon ring is in good condition (if not either replace it or use glue to glue in a bigger glass)
- Measure old glass and find an identical size (0.1mm too big or small will not work)
Now you are ready to fit the glass.
Friction fitted glass with nylon ring: place glass in place and press against wooden post or using a case back press to squeeze glass into watch case.
Glued Glass: I use epoxy resin. Place a small amount of mixed glue into the seat for the glass as evenly as possible. Wipe the excess glue away with your finger (I have never found a tool as good as a finger for smoothing and evening the glue, but you do need to wash your hands). Place the glass into its seat and and glue. the glue should be almost unnoticeable. Allow to dry and remove any excess glue before reassemble paying particular attention to the dial seat.
clean finger prints and marks from glass
Pressure Test the watch if the customer desires.