POLL -- annealing schedule for 104 COE

[dulceisler]

Currently imdoing 968F at 1 hr and then cooling to 850 for another hr and then letting the kiln cool down

[theglasszone]

Hi There!

Just my input - and bear in mind I'm using a kiln intended for PMC...I use the "programable" cycle to batch anneal my 104 stuff. Also, I work itty-bitty, tiny stuff...so I have to be careful with the heat level so as not to "slump" stuff while annnealling:

1 hour ramp up to 895F
1 hour hold at 895F
ramp down to 700F
15 min hold at 700F
Slow (overnight) cool down to room temp (this usually takes at least 3-5 hours)

I know this seems low, but I've had no problems with instability in the beads (use mostly Moretti)...my Big Hole Beads (which I am getting ready to launch on Etsy, my website, and do a distribution of at my local BIG bead store!) have been put through a "test" of sorts...I've been wearing them on a cable necklace, 24/7 for nearly 2 months...in the tub, to bed, etc. just to make sure they are good and solid - so far, no problems! I've even dropped a couple of them on the cement garage floor and they still didn't crack.

An aside note here - I've noticed that even though my program indicates the top temperature to be no more than 895F, I've seen the "thermostat" (digital) indicate fluctuations, even for a few minutes at a time, up to 915F. This contributes to my choice to keep it on the "low" side in the settings - I'm sure from the thermo indications that it's has small "spikes" that go above what I've programmed it for.

Hope this helps.
DeAnne in CA

[Rubiee]

Let's see.... I hold for 30min at 960*.
Then I drop to 400* at 600* an hour (so it takes about an hour) and then the kiln shuts off and cools from there.
I read somewhere that the temp you want to control cooling past is like.... 600 something? I could be wrong though.

[evolvingBeau]

Hold time is proportionate to the thickest part of any given piece. Since overannealing is NOT an issue it's best to err on the side of caution with both the annealing temp and soak time.
968F is the accepted annealing temp for Effetre/Moretti, but again err on the side of caution and go with the highest temp you can without slumping or marring your work. Not all pyrometers/thermocouples are 100% accurate.

I have the formulae but they are extensive and boring so I'll summarize.
An example, A 1" thick piece of Effetre glass requires a calculated soak time of 76.2 minutes. 1/2" requires 38.1 minutes. For a bead you would measure from the hole to the surface eg. the radius of the bead to determine the thickest part.
Besides the soak temp and time the cooling rate from annealing temp to below the strain point which is just above 850F for Effetre/Moretti, is just as important. Again you can err on the side of caution and slow cool to below 600F for assurance.
About 200F degrees per hour is an acceptable cooling rate for a 1" thick effetre piece of effetre from annealing to below strain point.
With a 1/2" inch piece you can go about 800F degrees per hour to below strain point.

[Hayley]

I work with a lot of striking silver glass, thus have to adjust my annealing temp so the glass doesn't strike in the kiln. I anneal at a lower temp for longer and only do this schedule for 104 COE.

Garage at 890F
Anneal at 910F for 1.45 hours
Ramp down to 750F over 2.5 hours
Turn off kiln - it's brick lined and will ramp down slowly

[gubnavnania]

Honestly, I'm using BE annealing schedule for COE104.

Garage at 960
Anneal at 970 for at least 1.5 hours
Ramp down 100 per hour to 700 hold for 30 min
Ramp down 346 per hour to 300
Turn off kiln.

Overkill???

[theglasszone]

Originally Posted by gubnavnania

Honestly, I'm using BE annealing schedule for COE104.

Garage at 960
Anneal at 970 for at least 1.5 hours
Ramp down 100 per hour to 700 hold for 30 min
Ramp down 346 per hour to 300
Turn off kiln.

Overkill???

Overkill? Not considering the beautiful beads you make and the success you have keeping them from cracking and blowing!!!!

DeAnne in CA

[tiggybubba]

I have a different one altogether again.

968 (unless its terra etc then 925) usually for 90 min
ramp down at 120/hr to 830
hold for 1 hr
ramp down 120/hr to 530
hold for 30 min.
Honestly I dont know why I do the second ramp down I just do.
Leslie

[laserglass]

i'm sorry, but your poll does not make any sense. annealing is a procedure, with various ramp rates and temperatures. the length of time you hold the glass (T3) depends upon how thick it is. see chart below.

[ewdb]

Originally Posted by laserglass

i'm sorry, but your poll does not make any sense. annealing is a procedure, with various ramp rates and temperatures. the length of time you hold the glass (T3) depends upon how thick it is. see chart below.

i'm glad this subject came up. i'm using and adapted version of an annealing schedule i found on WC but i have no idea if it's accurate or not based on the size of my beads. My beads are usually at least 1.5" in length/width but generally not very thick...

and Mark, (even tho i wish i could) i have absolutely no idea how to interpret your chart...

[laserglass]

ok an example. lets say that you do not batch anneal, you anneal and go. and lets say you are making focal beads that are 1/2 in diameter and 1.5 inches in length. the important dimension is the smallest dimension ,1/2 inch (line 3 of the chart). lets say you made your focal bead out of moretti glass. the chart says that you need to let the beads soak at 930F for 30 minutes after you put your last bead into the annealer. then you need to ramp down to 850F in 9 minutes or more (there is no maximum, if you want to do it in hours that is ok, but not any faster than 9 minutes). then let it soak for 4 minutes or more, and then ramp down to room temperature. if your are making 1.25 inch thick marbles, use line 6 from the chart. if you are using bullseye or boro, use the temperatures shown at the bottom of the chart. remember, these are minimum times, you can make any step longer.

now if you batch anneal, you need to follow the steps for T1 and T2. if you anneal and go, you start at T3.

[laserglass]

here is a slightly larger version of the chart

[Diane (clarus)]

The poll asks about "hold time." Are you asking about hold time during annealing (T3 Anneal Soak on Mark's chart), or strain point (T5 Strain Soak on Mark's chart)?

I'm still babysitting my kiln while batch annealing, but I follow the procedure in Jim Kervin's "More than you ever wanted to know about glass beadmaking" book; I believe the strain point he specifies is 680°F for 15 minutes; this is after a very slow ramp down from the annealing point.. I've been using an anneal point of 940°F since I use some silver glass, but it varies about 20 degrees during that cycle. Timing depends on my largest bead.

-Diane

[prairieson]

A couple of things I've noticed...

Remember that there's not an "official" annealing point, as such. There's an annealing range, which is anywhere between the strain point and the softening point (850 and 1060 respectively for effetre). Any temperature in that range can be an annealing point. Generally speaking, the lower the annealing point, the longer the T3 soak.

The strain soak (T5 on the chart) is a really important soak. You'll notice that the chart shows the strain soak takes place very slightly above the strain point of the glass, and with good reason. It gives the glass molecules a chance to catch up, temperature-wise, and find that final relaxed state before being "frozen" as the temp drops below the strain point.

If you're doing a strain soak below the strain point, it's not doing what is intended. A strain soak below 850 (for effetre) does nothing for the annealing process, the glass is already frozen by that temp and nothing is accomplished. It's pretty much a waste of time and electricity.

[Diane (clarus)]

Thanks for clarifying that, John. I'd always wondered if there was a specific temp at which glass MUST be annealed, or if there was a range that was appropriate (giving extra time with temps on the lower end, of course.)

-Diane

[Tink]

You really did explain that nicely, John!

[elle]

All this talk about strain point has me curious about something. Here is my schedule:

garage @ 960 then anneal @ 960 for 1.5 hours, sometimes 2 (depending on the size)
ramp down to 750 @ 50 degrees per hour from 960*
ramp down 100 degrees per hour to 500 degrees
shut off

*I always thought that a conservative ramp down through the strain point (mine takes 4.2 hours for the drop from 960 to 750) would be just as effective as the recommended 10 minute soak AT the strain point. I've had a very good track record when it comes to breakage (a few incompatibility crazes and beads that were already doomed going in), but to be extra safe, should I be focusing more on soaking at the exact strain point with my schedule?

Great info, btw!

Sarah

[prairieson]

Given the size of the work we do, I think that a slow drop through the strain point, like yours, is just as effective as a strain soak.

Originally Posted by elle

All this talk about strain point has me curious about something. Here is my schedule:

garage @ 960 then anneal @ 960 for 1.5 hours, sometimes 2 (depending on the size)
ramp down to 750 @ 50 degrees per hour from 960*
ramp down 100 degrees per hour to 500 degrees
shut off

*I always thought that a conservative ramp down through the strain point (mine takes 4.2 hours for the drop from 960 to 750) would be just as effective as the recommended 10 minute soak AT the strain point. I've had a very good track record when it comes to breakage (a few incompatibility crazes and beads that were already doomed going in), but to be extra safe, should I be focusing more on soaking at the exact strain point with my schedule?

Great info, btw!

Sarah

[Islandgirl]

Originally Posted by prairieson

Given the size of the work we do, I think that a slow drop through the strain point, like yours, is just as effective as a strain soak.

One also has to bear in mind that most of our pyrometers are not 100% accurate some may be out by 40 or 50 degrees so slowly cooling through the strain point makes sense.... Also the annealing temp between one colour of Effretti glass and another may be different by the same 40 or 50 degrees.... This means that their strain point is also different .... So unless you know that your pyrometer is accurate and you know the exact strain point of your glass.... SLOWLY COOLING the kiln is a more effective way to make sure your taking the stress out! (The bigger the bead the more slowly the kiln needs to be cooled!)

Lynne

[Hayley]

Originally Posted by prairieson

Remember that there's not an "official" annealing point, as such. There's an annealing range, which is anywhere between the strain point and the softening point (850 and 1060 respectively for effetre). Any temperature in that range can be an annealing point. Generally speaking, the lower the annealing point, the longer the T3 soak.

Thank you, John, for confirming this. . . with striking silver glass, if I anneal higher than 910, some turn brown. . . . thus my longer T3 soak at 910. Since I am making larger (thicker) beads now, I will add the strain soak at 850.

[evolvingBeau]

I also skip the strain soak in lieu of a very slow ramp down. (about 50-60 DPH).
As long as the temp changes are slow enough between annealing and strain point then you won't "un-do" the annealing by setting up new stresses in the glass.
As Lynne, said you can't always trust the pyrometer so nailing the right strain soak temp is harder than proceding through it slowly.

[elle]

Super, I'm glad to know I'm not the only one who skips the 10 minute soak, and that my schedule is just as effective. I got into the habit of doing it this way when batch annealing with an infinite switch - and an analog pyrometer. Of course, this super slow ramp-down isn't as difficult to pull off with a large all firebrick fusing kiln.

And as Lynne mentioned, I picked 750 just in case the pyrometer was a little off. And the higher the temperature, the more inaccurate they can be.

Thanks!

[gubnavnania]

Originally Posted by gubnavnania

Garage at 960
Anneal at 970 for at least 1.5 hours
Ramp down 100 per hour to 700 hold for 30 min
Ramp down 346 per hour to 300
Turn off kiln.

So I can just skip the 30 min soaking at 700? Or do I have to go slower than 100/hour from 970 to 700?

[prairieson]

Originally Posted by gubnavnania

So I can just skip the 30 min soaking at 700? Or do I have to go slower than 100/hour from 970 to 700?

Skipping the 700 soak should have no affect on your annealing, so yeah, I'd skip it. If you're getting good results with 100/hour, I'd stay with that.

[evolvingBeau]

Technically yes.
Provided that my math is correct..For a 1" thick piece of Moretti glass the maximum(fastest) slow cooling rate (annealing through strain) is 3.74 degrees F/min or 224 degreesF/hour.
So 100 DPH is acceptable as long as your largest piece in the kiln doesn't exceed a 1" thickness.

[gubnavnania]

Thank you both for the answer

[evolvingBeau]

If anyone is into the physics and formulae of annealing and want's a full on breakdown.. I recommend Bandhu Scott Dunhams' book, Contemporary Lampworking..One of the best all around lampworking books out there IMO. It has a similar table in the annealing chapter to the one Mark posted but much more detailed.
Complex formulae, but the process itself is very simple and straightforward provided that you know the threshold temps and basic soak times. Colors and striking are where it gets to be more of a tricky thing that each of us needs to experiment with individually due to the many variables such as kilns, glass chemistry, and the way that you actually work the glass prior to putting it into the kiln.

[Retta]

For me it's 15 minute for dinky beads but if they are medium I will bump it up to 30 and if they were large ( rare for me) it would probably be an hour.

[ewdb]

Originally Posted by laserglass

ok an example. lets say that you do not batch anneal, you anneal and go. and lets say you are making focal beads that are 1/2 in diameter and 1.5 inches in length. the important dimension is the smallest dimension ,1/2 inch (line 3 of the chart). lets say you made your focal bead out of moretti glass. the chart says that you need to let the beads soak at 930F for 30 minutes after you put your last bead into the annealer. then you need to ramp down to 850F in 9 minutes or more (there is no maximum, if you want to do it in hours that is ok, but not any faster than 9 minutes). then let it soak for 4 minutes or more, and then ramp down to room temperature. if your are making 1.25 inch thick marbles, use line 6 from the chart. if you are using bullseye or boro, use the temperatures shown at the bottom of the chart. remember, these are minimum times, you can make any step longer.

now if you batch anneal, you need to follow the steps for T1 and T2. if you anneal and go, you start at T3.

Whew, took me forever to find this thread again! Thanks for the explanation, it's all starting to make sense now...

[Holly]

Thanks guys!
I'm bookmarking this page.