Bottle Slumping

While I was on vacation over the holidays, my family supplied me with many beer and coke bottles. I'm starting to experiment with slumping them. Beer bottles first just to get the hang of it. I've actually not found too many sources on slumping bottles. I am starting to think people may be keeping there own firing schedules to themselves, trade secret. In any case I've started my first slump today using a schedule I found here http://www.bigceramicstore.com/information/Tip92.htm. I'll update this post once I have some results.

Segment	Rate	degrees F	Hold
1	500	500	12 min
2	500	750	12 min
3	600	1100	10 min
4	200	1300	20 min
5	250	1475	10 min	takes roughly 4.5 hrs to this point
6	9999	1100	1 hr
7	500	970	30 min	annealing occurs between 800-1000 deg.
8	120	750	20
Let kiln cool naturally.

I've now tried this process with 2 bottles. A beer bottle and a Mexican Coke bottle. Neither of them ended up with any vitrification, which is good. The Coke bottle did burn off the red in the label. I'm searching for a process to enable this to stay in tact. Perhaps a different firing schedule or spraying the bottle with the de-vitrification spray. I think people who have successfully done this are not advertising how they accomplished it. I'll report back once I try a couple more things.