1. Remove all labels and collars. Anything that is not painted on needs to be removed from the bottles. Anything plastic, will melt or burn out in the heat of the kiln
2. Cover the bottle with your favorite Devitrification solution. This will keep the bottle shiny instead of matte or mottled. We use Spray A, its lead free and food safe, but it stinks like bad minty mouthwash. I suggest painting it outside.
3. Cut out a length of Kiln Paper that is twice as wide as the bottle to accommodate for it shifting when being fused and flattened by the heat of the kiln.
4. Load your kiln and fire the bottle.
Choosing Full Fuse or tack Fuse for your bottle.
Full Fusing the bottle will make it really flat. The high temperature is around 1450 F. Each kiln will need its own special firing schedule. Firing Schedules for bottles will vary from one kiln to the other. Factors affecting firing schedule for slumping bottles are:
The size of the kiln, Location of the kiln elements, thickness of the glass, your specific pyrometer aka thermocoupler r for measuring temperature.
Tack Fusing Bottles. A tack fuse is done at around 1350F. The bottle becomes flat but it is not fully fused. There is still textured and lifted areas especially around the neck of the bottle and the bottom of the bottle.