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Boro Room -- For Boro-related tips, techniques, and questions. |
2010-07-20, 5:46pm
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Senior Member
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Join Date: Jan 01, 2009
Location: K'zoo, MI (wishing it were St. Thomas-USVI)
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How long to hold batch annealed boro beads?
Hi:
I have a Chili Pepper kiln and up to now I've used it to batch anneal soft glass. I've just started working with boro, making plain round beads (for now) nothing bigger than 15mm. The boro program ramps up quickly to 1050° then holds for 3 hrs. Is it necessary to hold for 3 hrs, or can that part be shortened?
Thanks
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BarbR in Kalamazoo.
Scorpion, bulk propane, 2 5lpm oxycons, tanked O2, a Minor and a HH (just in case)
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2010-07-20, 5:55pm
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Lampworker
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Join Date: Jul 06, 2007
Location: Oregon
Posts: 211
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3 minutes for every millimeter thickness
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2010-07-20, 5:55pm
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Senior Member
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Join Date: May 31, 2009
Posts: 368
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Ive always heard 3min/mm and that works out to 45 min. I would probably go with an hour.
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Melting boro with a National 3A and and two Devilbiss 5lpm 10psi concentrators.
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2010-07-21, 1:38am
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Alaska Boro
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Join Date: Dec 10, 2009
Location: Anchorage, Alaska
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The soak time for items less than one inch thick is 15 minutes. This is long enough to remove the stress.
For items over one inch use a soak time of 15d squared. If the piece is 2 inches thick then (2 x 2) x 15 or 60 minutes.
See page 217 in "Contemporary Lampworking" for additional information.
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2010-07-21, 12:22pm
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Senior Member
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Join Date: Jan 01, 2009
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Thank you all. This is very useful information.
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BarbR in Kalamazoo.
Scorpion, bulk propane, 2 5lpm oxycons, tanked O2, a Minor and a HH (just in case)
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2010-07-21, 12:50pm
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Marbles, dude, Marbles
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Join Date: Jan 06, 2007
Location: Coral Springs, Florida
Posts: 653
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60 minutes to anneal a 2" marble?
Quote:
Originally Posted by Alaska
The soak time for items less than one inch thick is 15 minutes. This is long enough to remove the stress.
For items over one inch use a soak time of 15d squared. If the piece is 2 inches thick then (2 x 2) x 15 or 60 minutes.
See page 217 in "Contemporary Lampworking" for additional information.
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Does this mean that I can safely anneal a 2" boro marble for 1 hour and then turn the kiln off and let it cool? And I shouldn't have to worry about it cracking in a few days or weeks or months? I anneal my 2" marbles for 5 hrs at 1050, drop to 960 at 60 degrees/hour and hold at 960 for 2 hours before turning my kiln off. I put way too much effort into my marbles to trust 1 hr of annealling time. I know this thread is about annealling beads, but a formula is a formula and should apply to everything.
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A marble a day keeps the 'willies' away.
Gerald Kappel
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2010-07-22, 3:29pm
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Senior Member
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Join Date: Jan 07, 2008
Location: Gloucestershire, UK
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Interesting , Im about to batch anneal boro for the first time as well, I usually batch my soft glass,,,,,
So I ramp my kiln up (paragon SC3) hold it for 1 hour (I have nothing bigger or nowhere near 1") and then.... do I ramp it down, or just turn it off?
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Bob Cat and 2 oxycons
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2010-07-26, 4:10am
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Pyromaniac
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Join Date: Aug 12, 2006
Location: Memphis, TN
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Some people just turn it off if they have a brick kiln, but I ramp down to 950 at 60 per hour and then off.
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Lana
Sexy Barracuda and Mirage
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2010-07-26, 6:03am
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Senior Member
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I've yet to run another batch and hold for an hour. I don't make that many boro beads and it's been too darn hot to run the torch full blast. As soon as I get enough done up, I'm going to revise the anneal schedule to hold for an hour and see how that goes. The rest of the schedule I'll leave as is as far as ramping down.
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BarbR in Kalamazoo.
Scorpion, bulk propane, 2 5lpm oxycons, tanked O2, a Minor and a HH (just in case)
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2010-07-26, 12:31pm
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The Venerable Bead
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Join Date: Jul 22, 2005
Location: Rhode Island
Posts: 1,951
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as smiley always says "soak longer than you think and ramp slower than most say to". with that being said I would soak for at least an hour at 1050 or higher (depending on colors) and ramp down to 950 and hold for 30 minutes and then go down 60 degrees an hour until you reach 500 and then off.
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To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Paula AKA The Venerable Bead To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
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2010-07-27, 7:41am
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Pyromaniac
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Join Date: Aug 12, 2006
Location: Memphis, TN
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I always thought it was annealing at 1050 F for an hour per inch of thickness.
The thicker it is, the slower the ramp down to 950.
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Lana
Sexy Barracuda and Mirage
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2010-07-29, 12:22pm
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boro color bender
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Join Date: Jun 06, 2005
Location: The Oregon coast!
Posts: 10,039
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The thicker the glass, the longer it has to soak and the slower it has to ramp down... it's not a straight equation. It is exponential. A two inch piece does not take twice as long as a one inch piece... it takes much much longer.
When you think about annealing, just realize that glass is an EXCELLENT insulator... it holds heat very well... and you have to cool the center of the piece at about the same rate as the outside to keep from introducing stress on the ramp down...
A perfect example is the mega-planet Josh Simpson did for Corning... it was over 100 pounds and the ramp down was ridiculous... he wasn't successful on the first attempt... I'm not sure how many they did before they went slow enough, but memory tells me the one that survived was in the kiln more than 6 months... yep... i said months. He routinely has pieces in the kiln for a month or so and they are not insanely thick... it just takes that long to properly anneal thicker work.
beads are relatively easy... hold for an hour or two at soak temp and then ramp at 60 per hour to strain point... this will work for most of our smaller stuff.
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