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Tips, Techniques, and Questions -- Technical questions or tips

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  #1  
Old 2015-12-14, 6:32am
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Khaleesi Dane Khaleesi Dane is offline
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Default Annealing info and frustration!!

First, let me just say thatI am having no problems with my beads. They come out bright and shiny, and the one that I dropped on the concrete floor this morning bounced and was fine. That said.....

I wish I could find some consensus on an annealing schedule. I mean really!!

The schedule that came with my kiln says start at over 1000. Degrees Fahrenheit! Um, no, I work with silver glass, so I have my top temp set at 960. ( which seems at least to have agreement from many ) I soak 2 hours from last bead put in, that's pretty consistentantly agreed on.

BUT, where is this magical stress point temp? Most people/websites say 700. Corning glasses website says 450! That's a big difference. I make big and small beads in the same day. I make spacers to match my focals. I have been using a slow 100 degrees an hour ramp thru 650, then just letting it cool....

Am I am supposed to go slow all the way to 450?

I have searched here and read soooo many threads on this, and on Facebook, and on my kiln site, the lauscha ( flame dame site ) and Cornell, and too many others to count. I am beginning to think nobody really knows, that we are all just winging it! And that frustrates me, cause here in NH we have a wicked situation with extremely high electric rates. Some of the highest in the whole country.

So, what's a girl to do? Without embellishment, could people tell me what their annealing schedule is? Just list it out. Example;

Start at 960
Soak 2 hours
Ramp down 100 degrees per hour to 700
Shut down to cool to room temp, untouched.

I wanna see if we all have our ducks in at least the same pond, if not in a row...
Thanks!

Last edited by Khaleesi Dane; 2015-12-14 at 6:35am.
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  #2  
Old 2015-12-14, 10:03am
kansassky kansassky is offline
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I have found this schedule works for everything I do, including the most sensitive reactive glass. My beads are never more than 1" in diameter. If you make big ol' beads, others may have better advice.

Start at 920. Soak 15 minutes at 920.
Ramp down @ 200 degrees per hour to 850. Hold 15 minutes at 850.
Ramp down @ 200 degrees per hour to 700. Hold 15 minutes at 700.
Ramp down @ 200 degrees per hour to 400. Hold 10 minutes at 400.
Kiln cycle complete.

Wait to open kiln until 100 degrees or less.
(If kiln is still above room temp, I open doors and let beads cool to room temp.)

Side note: I had a very frustrating experience with reactive glass (over-striking) until I compared the kiln temps to an oven thermometer. I discovered my kiln is actually 40 degrees hotter inside than it shows on the controller. So, I adjusted all of my scheduled temps (reduced them 40 degrees) and ran a test cycle to be sure the targets were correct. Voila! Perfect. Right on the money.

This is the kind of oven thermometer I used for comparison. Set kiln for 450. The oven thermometer read almost 500!
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  #3  
Old 2015-12-14, 10:24am
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OK First off that 450 from Bulseye is gong to mean centigrade not fahrenheit.

Google says it equals 842 fahrenheit.

Next Boro needs 1000 f I think and 104 coe wants 920 f garaging temperature.

Everything I have seen says figure plus or minus 50 f due to different glass constituents and different kilns and different thermometers.

There is this temp called the "strain point" where what ever stress still in the glass is going to stay in the glass at any temp below that.

For coe 104 I think it is around 820 or some such.

I cool mine at 100 f per hour from garage temp to 800 f.

Under the strain point the internal stress doesn't change but the glass is still susceptible to breaking due to thermal shock so it still needs to cool slowly.

My memory gets sketchy about how slowly to cool from there to room temp but I cool my beads at 200 f degrees per hour down to 400 f then I turn off the kiln heat and just let the kiln cool to 100 f.

Usually this is an over night thing so it is room temp by the time I get up.
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Old 2015-12-14, 10:52am
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Contemporary Lampworking books by Bandhu provide an excellent technical explanation of stress and annealing, formulas to calculate annealing cycles as well as some example cycles. These books are widely considered the "Bible" of Lampworking and well worth the investment to purchase.
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  #5  
Old 2015-12-14, 11:13am
glass butterfly glass butterfly is offline
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Question

Is the annealing temperature and the cool down schedule affected by whether the kiln is a fire brick lined one such as the Paragon kilns or a kiln that has fiber blanket lining such as a Chili Pepper?

I had read somewhere that for a Paragon kiln, one could just shut the kiln off after annealing the beads and that the kiln cools down slowly enough that it is safe for the beads. I've been bringing up the kiln to 960 and using that as a garaging and annealing temperature and shutting it off about 1 hour to 15 minutes after I make the last bead and then not opening the kiln until the next day. My kiln is set to stay at 960 for 4 hours since I can only make beads for about 2-3 hours at a time. My beads have been fine except for the ones with silver glass, so I need to lower my garaging temperature.

If I lower the garaging temperature to 920( is that a good temperature) what does the annealing temperature need to be and the schedule for cool down?

I recently bought a larger Paragon kiln so that I could use center dipped mandrels but have been unsure how to program it and would very much appreciate help from the more experienced folks here on LE. Thank you. Lydia
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Old 2015-12-14, 2:35pm
kansassky kansassky is offline
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I don't ever anneal 104COE glass beads starting higher than 920F.
While working, I keep my kiln at 900F.

Schedule for ramp down is listed in post #2 above.
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Old 2015-12-14, 3:35pm
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If you decide to lower your annealing temp (annealing for me meaning the time from last bead into the kiln until the temp gets down to the strain point { 830 for me} ) then you can trade time for temperature somewhat.

If I am working silver glass that does not like higher temps because I don't want the glass to strike any more than when I put it in the kiln I will set my garaging temp to 900 f and change the cooling rate from 2 hours to 3 or 4 hours to get down to 830 f.


As to whether a kiln will hold temp long enough to allow proper annealing time and a slow enough cool down to room temp I would only trust shutting the kiln heater control off if I had tested that kiln and tracked the cool down rate myself without regard to what it is made of, fiber or brick.
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Last edited by Speedslug; 2015-12-14 at 3:40pm.
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  #8  
Old 2015-12-14, 5:21pm
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Quote:
Originally Posted by glass butterfly View Post
Is the annealing temperature and the cool down schedule affected by whether the kiln is a fire brick lined one such as the Paragon kilns or a kiln that has fiber blanket lining such as a Chili Pepper?

I had read somewhere that for a Paragon kiln, one could just shut the kiln off after annealing the beads and that the kiln cools down slowly enough that it is safe for the beads. I've been bringing up the kiln to 960 and using that as a garaging and annealing temperature and shutting it off about 1 hour to 15 minutes after I make the last bead and then not opening the kiln until the next day. My kiln is set to stay at 960 for 4 hours since I can only make beads for about 2-3 hours at a time. My beads have been fine except for the ones with silver glass, so I need to lower my garaging temperature.

If I lower the garaging temperature to 920( is that a good temperature) what does the annealing temperature need to be and the schedule for cool down?

I recently bought a larger Paragon kiln so that I could use center dipped mandrels but have been unsure how to program it and would very much appreciate help from the more experienced folks here on LE. Thank you. Lydia
Shutting the kiln off because it's brick does not necessarily anneal the beads. For instance, I have a Bluebird XL. It's brick with a fiber door. One day I lost power in the middle of torching and the kiln went down over 300 degrees in one hour. To me that's way too fast through the strain point and the glass, IMO, didn't anneal properly.

My kiln runs a bit hot. I garage at 900F and anneal 75F to 750F. (that covers the strain point of all the soft glass I have, and then some) Then from 750F I'll go 100F down to 500F and off. That works for me. Every single kiln I've had is different though and some are calibrated more precisely than others.
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Old 2015-12-14, 6:35pm
glass butterfly glass butterfly is offline
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Thank you for your advice. Looks like I'm going to first buy an oven thermometer and check to see how precisely my kilns are calibrated and then reprogram my small kiln and program my larger kiln to reflect the working and annealing temperatures suggested. My beads are mainly one inch and smaller, so won't worry about annealing large beads. Lydia
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Old 2015-12-14, 7:22pm
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I would suggest getting one of those infra red temperature guns.

They have them with a range up to 1200 f and the accuracy is going to be alot better.

Mine is plus or minus something like 15 degrees f.

They are also better for getting an idea of how the heat is distributed as well as finding cold spots in the house without a ladder.
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Old 2015-12-14, 8:55pm
glass butterfly glass butterfly is offline
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What is an infra red temperature gun and where would I get one? Are they expensive?
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  #12  
Old 2015-12-14, 11:46pm
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I got mine on Amazon.

I think it was $19 and I shipped it with some stuff so I think it was no cost but my memory is not functing well these days.

This is the one I got;

http://www.amazon.com/gp/product/B00...ilpage_o07_s00
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Last edited by Speedslug; 2015-12-14 at 11:48pm.
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  #13  
Old 2015-12-15, 6:03am
glass butterfly glass butterfly is offline
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Thanks. Just ordered one. 😊 Lydia
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  #14  
Old 2015-12-26, 9:26am
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FosterFire FosterFire is offline
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Just a quick FYI: the most detailed info on annealing in print is in Bandhu Scott Dunham's books.
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