7. Use the silicon carbide sandpaper along the outside and inside edges to create a curved, smooth edge. Also, use it to sand any rough spots you find. 8. Wipe the bottle or glass with a wet paper towel along the edge. Run it through the dishwasher.. Use the silicon carbide sandpaper along the outside and inside edges to create a curved, smooth edge. Also, use it to sand any rough spots you find. 8. Wipe the bottle or glass with a wet paper towel along the edge. Run it through the dishwasher.