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Checking kiln temperature????

Posted: Sat Apr 05, 2003 11:00 pm
by Carla
The temperatures we are firing at seem "odd." Plus we have two different kilns and they don't fire the same way at the same temps and schedules.

Is there some clever way to test what the REAL temperature is in the kiln? We do have pyrometer's but I'd like to know what temp I'm really hitting.
Thanks.

Carla :?

Posted: Sat Apr 05, 2003 11:05 pm
by Tony Smith
Carla,

There are a number of factors that go into determining the "real" temperature in a kiln. Location of the pyrometer, distance of the pyrometer from the elements, volume of the kiln, distance of the pyrometer from the glass, etc...

I think the best that you can do is to get a handheld thermocouple meter and use it to read the temperature of both kilns. Then you will have a common temperature reading to adjust and calibrate to.

You can get hand held thermocouple meters from http://www.omega.com. They are relatively inexpensive and work very well. If you are interested, I can provide additional information including model numbers of the meter and the thermocouple itself.

Tony

Posted: Sun Apr 06, 2003 12:26 am
by Brad Walker
Another way to test the temperature in your kiln is with ceramic cones. Each cone is set up for a different temperature, so you can get some idea of how accurate or inaccurate your kiln is.

Also, there's a lot of good information in Bullseye's "Knowing Your Kiln" TechNotes No. 1: http://www.bullseyeconnection.com/pdfs/ ... tes_01.pdf

Posted: Sun Apr 06, 2003 4:22 am
by Colin & Helen
The important factor when using cones Orton or Seger is time taken to reach the cone temperature... Orton cone 015 heated at 60c per hour will bend at 790c.. increase the rate to 150c per hour now the temperature will be 805c..then at 300c per hour you would be looking at 845c .It is also best to use 3 cones when testing for temperature i.e. one each side of the required temp...016 would be flat on the shelf...015 would be just touching the shelf this also is the aim point 014 is only just starting to bend.

Colin

Posted: Sun Apr 06, 2003 6:10 am
by Tony Smith
The cone method, while inexpensive, is a way of measuring heat work, or the combination of time and temperature as Colin so clearly stated. While it will get you in "the ball park" it's not an accurate way of knowing what the "real" temperature is in the kiln.

Tony

Posted: Sun Apr 06, 2003 6:58 am
by rosanna gusler
hi all, i think 'knowing your kiln' and keeping a log for each kiln is much more helpful than worrying about the different numbers. heat work performed is really what matters. i have 3 kilns and they all do the same heat work at different numbers. full fuse (float) varies from around 1500 to 1750f. i thought at first it was a reflection of different thermocouples . but i moved one thermocouple around and yep those temps were those temps. i just have seperate notebooks for each kiln. rosanna

Posted: Sun Apr 06, 2003 11:59 am
by Carla
:|

Hummmmmmm. I have a friend who would set me up with cones, but I agree that is not the straight forward answer. So the question is to thermocouple or not.

While ya'll slept I did a test on both kilns giving them the same glass, frit, stringer, confetti to fuse at 1350, 8 min hold. The BEEG glass kiln (top elements) mushed things way down, full fuse and then some. The little clay kiln with no top elements tack fused them.

I think you are all right. I do have kiln logs....but the quasi scientist in me wants to know the "real" truth.

Thanks. This is very helpful.

Carla

Posted: Sun Apr 06, 2003 1:16 pm
by PaulS
Even if you do the cone thing you will end up with two sets of results; one set for each kiln, right?

So if you set your temperature controlling device (I'm not familiar with how a pyrometer works) until you acheive the required result for each kiln, just use those values every time for each kiln.

It's definately worth reviewing the "Knowing Your Kiln" TechNotes Brad mentioned.

From the test results you described, there could be 200degF between each firing.

Short answer Carla; you need a controller and thermocouple to save you time and glass in experiments :wink:

HTH,

Paul

Posted: Sun Apr 06, 2003 1:26 pm
by Carla
Still pondering.

The tech notes from BE seem to be more about uneven temps throughout your kiln. I'm more interested what 1350° means in my kiln. I look at Brad's book and he says BE tacks at (1300-1400). (He also sez "know your kiln.") But it appears in my big evenheat coffin kiln w/ top elements 1350° is way beyond a tack fuse.

I'm thinking Rosanna has the right idea....to know what your kiln does at which number and if the numbers don't line up with numbers in various books or guides look for the results you want and adjust accordingly.

Inotherwords, should I really be messing with my pyrometer & all it's electronics or just know that at 1350° I get a really full fuse in my big kiln?

Carla, thanking you all for pondering with me.

Posted: Sun Apr 06, 2003 4:02 pm
by Brad Walker
Carla wrote:Inotherwords, should I really be messing with my pyrometer & all it's electronics or just know that at 1350° I get a really full fuse in my big kiln?


I think this is on the right track. So long as you know how your kiln behaves at whatever temperature it says on your pyrometer, then it doesn't really matter what the temperature REALLY is. If 1350F is a full fuse, then just go from there.

One other comment -- if you do want to know the REAL temperature inside of your kiln, then a handheld probe like the one Tony mentions in his post would probably be the way to do.

Posted: Sun Apr 06, 2003 5:44 pm
by wingoda
I have been working on trying to understand the temperature inside my large paragon ceramic kiln for some time. I have kept some records on firing and have stopped overfiring. I have a digital controller that indicates temperatures that are off from the way the BE glass appears. I have adjusted some for the variance in fusing temperature but how does one go about determining annealing temperatures with a controller that doesn't match the internal temperature? I looked on the site for the hand held temp probes but didn't see a model that would be right? Any suggestions on a model number?

Thanks...

Posted: Sun Apr 06, 2003 7:16 pm
by Bert Weiss
Brad Walker wrote:
Carla wrote:Inotherwords, should I really be messing with my pyrometer & all it's electronics or just know that at 1350° I get a really full fuse in my big kiln?


I think this is on the right track. So long as you know how your kiln behaves at whatever temperature it says on your pyrometer, then it doesn't really matter what the temperature REALLY is. If 1350F is a full fuse, then just go from there.

One other comment -- if you do want to know the REAL temperature inside of your kiln, then a handheld probe like the one Tony mentions in his post would probably be the way to do.


I came to this thread late. Brad has the right answer here. The only thing that matters is your results and your annealing. The high temp results are a factor of time/temp. The same work can get done at a lower or higher temp depending on the quality of heat" and the amount of time it takes to get there.

Observe your results, and keep good notes. You should be able to get repeatable results.

For annealing at the right temp, do a slump test ala Lundstrom "fusing book one" also check the archives. This test will locate the annealing temp for a particular glass in your kiln with your thermocouple and control system.

There is nothing like doing the work to figure out your kiln and controller.

Posted: Mon Apr 07, 2003 12:50 am
by Lynne Chappell
Carla: It seems to me that the small kiln is the one reading the correct temperature. The biggest problem is determining the annealing temperature if the pyrometer isn't reading correctly. I think a cone test would confirm that the big kiln is significantly off.

I dealt with a kiln reading an incorrect temp for quite a while, and trying to guess where the correct annealing point is was a pain. The pyrometer may not be off the same ratio at 950 as it is at 1350.

Posted: Mon Apr 07, 2003 4:33 am
by PaulS
Carla wrote:Still pondering.
snip>>>>>
The tech notes from BE seem to be more about uneven temps throughout your kiln. <<<<<snap


Yes you are right Carla. Sorry, I should have explained better to say that the critical thing is, to record the temperature the glass starts to move.

Start with one kiln and record your figures when you are getting the glass to do what you want it to. These would be your reference points when write your firing schedules.

Then, adjust your firing schedules for that kiln.

Don't worry that it takes a while -some civilisations took generations to get it right! :lol:

Paul

Posted: Fri Apr 11, 2003 3:49 pm
by Carla
A follow up on what I discovered with all my experimenting.

Shortly before I posted the first time reagrding kiln temps, we had added a fiber board to our kiln and had placed it directly on our ceramic shelves, thus raising the shelf 1/2".

What I didn't notice is that this little change put the shelf in conflict with my pyrometer. Oops. So it was no longer reading the temperature right.....

I freaked out with my odd/overfused pieces....posted, worried, fretted, read what you all said. Then I stopped & took a deep breath and started thinking. Once I realized when the problem started I relooked at the shelf, dropped it down, pushed it further from the pyrometer and started test fusing again.

Now I am getting results that seem more in line with what "should" be happening at certain temps, plus I feel certain my annealing is happening at the correct temperature.

The moral for me....is know your kiln, and consider when the problem started and what preceeded that.

Thanks for all your input. I am much smarter as a result.

Carla

Posted: Fri Apr 11, 2003 3:56 pm
by charlie
Carla wrote:The moral for me....is know your kiln, and consider when the problem started and what preceeded that.

Thanks for all your input. I am much smarter as a result.

Carla


working at a computer manufacturer doing customer service, the first question i ALWAYS ask is: if it used to work, what did you change?