Slumping schedule for 9 mm thick piece

For discussion of processes related to using Bullseye glass, including kilnforming and kilncasting, torchwork, blowing and stained glass.

Slumping schedule for 9 mm thick piece

Postby Dales Funky Glass » Thu Jul 29, 2010 10:34 am

Hello everybody,
I am new to the forum, looks like there is a lot of great information & people here.
I am slumping a piece that is 9 mm thick, size is about 7x11 inches, the middle contains a pot melt (6mm thick) that I cut up. There is a border 1.5" wide around the melt with a 3 mm layer of opague red on top of Bullseye tetka clear, and then there is a layer of Tetka clear over the whole thing.
My original schedule in a Paragon 24 was:
275 to 1225, 40 min
500 to 1440, 10
Full to 900, 60
100 to 700, 0
full to 85, off
I found this schedule for a 12mm piece:
150 to 1150, 5min
600 to 1250 10 min
full to 900 3 1/2 hrs
40 to 800,0
80 to 700, 0
full to 85, off

Any recomendations on this schedule/different one & where I could speed up the process? How much could I cut back the annealing at 900 degrees and speed up the fall between 900 to 700?
Thanks,
Dale
Dales Funky Glass
 
Posts: 3
Joined: Thu Jul 29, 2010 9:34 am

Re: Slumping schedule for 9 mm thick piece

Postby Stephen Richard » Thu Jul 29, 2010 11:02 am

Dales Funky Glass wrote:Hello everybody,
I am new to the forum, looks like there is a lot of great information & people here.
I am slumping a piece that is 9 mm thick, size is about 7x11 inches, the middle contains a pot melt (6mm thick) that I cut up. There is a border 1.5" wide around the melt with a 3 mm layer of opague red on top of Bullseye tetka clear, and then there is a layer of Tetka clear over the whole thing.
My original schedule in a Paragon 24 was:
275 to 1225, 40 min
500 to 1440, 10
Full to 900, 60
100 to 700, 0
full to 85, off
You certainly had me confused for a bit - combining metric and Fahrenheit!
I found this schedule for a 12mm piece:
150 to 1150, 5min
600 to 1250 10 min
full to 900 3 1/2 hrs
40 to 800,0
80 to 700, 0
full to 85, off


Overly long soak at annealing point (in my oppinion).
My suggestion would be to treat this piece as at least 12mm, possibly 15mm.
At 12mm - initial heat at 140C to slump temperature, no intermideiate soaks, no fast rises. Afap to annealing temp - for Bullseye I would use 482C and then use the Bullseye soak for thick pieces which is 2hrs then 55/hr to 427 and 99 to 370C , finally 330/hr to 21C
At 15mm - initial heat at 90C/hr to slumping temp. Bullseye schedule suggests 3hr soak, 25 to 427, 45 to 270, 150 to 21C.
Bullseye recommendations on annealing here: http://www.bullseyeglass.com/pdf/other_ ... _slabs.pdf


Any recomendations on this schedule/different one & where I could speed up the process? How much could I cut back the annealing at 900 degrees and speed up the fall between 900 to 700?
Thanks,
Dale
Stephen Richard
 
Posts: 198
Joined: Mon Jan 25, 2010 9:02 am

Re: Slumping schedule for 9 mm thick piece

Postby Dales Funky Glass » Thu Jul 29, 2010 12:08 pm

Stephen,
Thanks for the link and info. The numbers were if degrees F.
I'll anneal it between the rates for 12 and 19 mm per the chart, and speed up the initial rate.
Dale
Dales Funky Glass
 
Posts: 3
Joined: Thu Jul 29, 2010 9:34 am

Re: Slumping schedule for 9 mm thick piece

Postby Lynn g » Thu Jul 29, 2010 12:31 pm

Two of the most important things to remember in working with glass:

1. Speed kills.
2. Patience is a virtue (and its own reward).
Lynn g
Central Calif.
Lynn g
 
Posts: 41
Joined: Thu Jan 21, 2010 2:00 pm

Re: Slumping schedule for 9 mm thick piece

Postby Dales Funky Glass » Fri Jul 30, 2010 6:00 am

Lynn,
I should have read you words of wisdom before slumping, :cry: it cracked.
I will upload some photos. From what I have read here, it may have cracked during slumping on the way up to 1250? My schedule was:
200 to 1150, 5 min
600 to 1250, 10 min
full to 900, 2 1/2 hours
45 to 800, 0
80 to 700, 0
500 fro 700 to 70, off

Should I eliminate the 600 rate from 1150 to 1250 (I didn't want it to get devitrified & overdid it), I'll probably also cut the rate on the final step in half.

Any comments on my first melt that I cut up and made into another piece?

Thanks,
Dale
Melt-Platter-web.jpg
Crack from the top
Melt-Platter-web.jpg (78.76 KiB) Viewed 1613 times
Melt-Platter2-web.jpg
crack from the bottom
Melt-Platter2-web.jpg (59.95 KiB) Viewed 1613 times
Dales Funky Glass
 
Posts: 3
Joined: Thu Jul 29, 2010 9:34 am

Re: Slumping schedule for 9 mm thick piece

Postby charlie » Fri Jul 30, 2010 8:10 am

once you're above ~1000f, it can't really crack, although there's no guarantee that the glass was at 1150 when the air temp (as measured by the thermocouple) was at 1150, so . this was probably caused by the ramp from cold-1150 being too fast.
charlie
 
Posts: 282
Joined: Wed Jan 20, 2010 9:52 am

Re: Slumping schedule for 9 mm thick piece

Postby Lynn g » Fri Jul 30, 2010 9:11 pm

What a shame...such a lovely piece.

9mm is pretty thick for 200 dph. I like to ramp up at a consistent speed all the way to my top temp (say 200dph to 1250), rather than try to rush it above 1000. I think of it as letting the glass relax into the mold, instead of forcing it to take the shape.
Lynn g
Central Calif.
Lynn g
 
Posts: 41
Joined: Thu Jan 21, 2010 2:00 pm


Return to Technique

Who is online

Users browsing this forum: Yahoo [Bot] and 1 guest