Kiln Issues

[Ciel]

When I got my SC2 I set it to the recommended garaging program with a temp of 510C - this was too high and most of my beads had kiss marks on, which was really disheartening at the time.  I gradually adjusted the temp until it was garaging at 480C and annealing at 485C.  I check beads periodically to make sure that they're annealing properly.  Anyhow, this temp has worked reasonably fine for 2.5 years. 

In the last few weeks, the kiln has decided to make all the beads stick together again - looks like the thermocouple might be failing.  Anyhow, at the moment on each morning I'm switching on the kiln, reducing the temp by 5C, and making a couple of clear beads and testing them to make sure they're still annealed. I then garage anneal on an evening using this new setting to see how many beads are successes or failures.

I'm currently garaging at 470C and annealing at 475C.

Has anyone else experienced this problem?

Cheers,
C-L

[Trudi]

no idea, sorry

[Princess Peggy (Priscilla McGirr)]

My one runs a bit hot too, and always has done...at the moment it says the room temp is 25 degrees and i don't think so!  I have trouble with 'kissing' too and now use the metal rod holder thingy that came with it to keep my beads separated.
Maybe I need to adjust the temperatures down a bit.  However it is the same age as yours and so far has not got any hotter as far as I can tell, although once it ran away with itself and shot up something alarming and made a beeping noise until I let a bit of cool air in the  bead door.

[Ciel]

I think it'll have to be trial and error to see if I can get the correct temperature again.  If not, I might have to replace the thermocouple instead (or buy a bigger new kiln!).

[Blue Box Studio]

Have you called Cherry Heaven in Corfe Castle?  They are the Paragon repairers so might have a clue what's happening with your kiln.  So far, mine's been reliable (tempts fate!).

[Pat from Canvey]

Are you perhaps now putting the beads in a bit too soft? I sometimes have a tendency to do this.

[flame n fuse]

I also have an SC2 and find that annealing at what it says is 485 is fine. We have another larger kiln and also find that it runs hot.  I think there was a thread here about checking kiln temps, does anyone know where it is?

[KatheL]

I have the same problem with my SC2 that i bought from Cherry Haven a few months ago. I use it for batch annealing beads, but also need to use it for other jobs where the correct temperature is essential!
My beads have "kiss marks" and a few are slumped together. All the ones resting on the kiln-washed buttom plate, have kiln-wash melted into the surface!
I run the kiln to 520 C, and have sat and watched it closely, it goes to 523 before going down.
Obviously the kiln is too hot, and Rob at Cherry Haven just suggested I experiment till I find a lower temperature. First of all, I dont fancy spending loads of glass an electricity trying to find something that might work, I don't have any means of finding out whether the beads will be properly annealed at the lower temperature, and finally I doubt I will be able to use this temperature info for precision demanding jobs.
I am very frustrated by all this, the purchase of this kiln was a big investment for me, and I did expect a brand new kiln to just - work.......any help is appreciated, please!
Kathe, Denmark

[Margram]

My SC3 has always read room temperature as ten degrees higher than it actually is. So I lowered my top temperature by ten degrees. I check a clear bead periodically to make sure I am still annealing correctly. You can do a search on the forum Kathe to see how to check for annealing using various means - I use a pair of sunglasses and my computer screen! 

[Margram]

I've just had a thought, Ciel - I wonder if your thermocouple has become displaced and is not protruding into the kiln enough?

[MeadMoon]

I've just had a thought, Ciel - I wonder if your thermocouple has become displaced and is not protruding into the kiln enough?

Yes, that's what I would have checked first as well.

[oliver90owner]

Annealing is not so much about the absolute maximum temperature and more about the cooling rate from the high.  If the temperature is too high, then the beads will soften and will eventually melt - if the temperature continues to rise....

Position of the thermocouple is always an issue, as is the postion of the elements (think slumping kilns as opposed to the SC2 per eg.)  As long as the temperature at any point in the kiln is stable, it is just a matter of taking the reading and any known error into account when programming the controller.

[Zeldazog]

First of all, I dont fancy spending loads of glass an electricity trying to find something that might work, I don't have any means of finding out whether the beads will be properly annealed at the lower temperature, and finally I doubt I will be able to use this temperature info for precision demanding jobs.

The SC2 only uses something like 50pence per firing cycle Kathe, so if you only put in a few clear beads on a couple of test cycles you won't be wasting much glass or electricity.

All kilns vary slightly, even the same make from the same manufacturer will show a difference, and they will also alter over time too.

Both the fusing kilns I have had have full fused at a good 10 or 15 degrees below Bullseye recommended temperatures - and were like it from new - I adjust for that.

[♥♥Tan♥♥]

I have found with kilns that it is safer to assume that the programmed temps are just an approximation, all of my kilns both ceramic and glass have fired higher or lower than suggested temps. The best thing to do is sit down and spend some time learning what the kiln does rather than assume it's ready to rock out of the box, no doubt some are but I have never found that.