SC2 overfire and burnt inside

[theseahorse]

Following on from the kind help I received on here, I treated myself to an SC2 with a bead door. I've been a bit nervous about firing it up, so I thought I would toast the new year by a 'simple' firing.

I followed all the instructions for a single speed firing. To be safe, I thought I would just dry some kiln wash on a fusing mould at a low temp rather than doing anything with glass at higher temps. I set it to go to 250 degrees C on full power and then hold at that temp for 15mins.

Anyway, the temp rapidly climbed to about 324 degrees C and I could see smoke coming out from the door (which was firmly shut). It then beeped a lot and the display briefly showed "14 mins" (not sure if that was how much time left or how much time it had had?) then switched between "HtdE" (High temperature deviation) and the temp, which gradually dropped down to less than 250.

I wasn't clear when it would have started timing the 15mins as the time didn't show on the display again. The instructions implied that if you press the down arrow, the rate, temp, hold etc will display one after the other, but firing will continue. Out of curiosity I pressed this and the "HtdE" changed to "Idle" and this continued to alternate with the temp, which kept dropping. I didn't get a "CPLt" message, but I knew at least 15mins had passed since it got above 250 degrees C, so I just switched it off and unplugged it.

This morning, this is what the inside of the kiln looked like:


And this is what the bead door looked like. I can't remember whether the inside of the bead door was white beforehand. It looks pretty brown/black now!


I realise having read previous threads that it was probably unwise to select full rate when aiming for such a low hold temp, but is anyone able to help me make sense of what happened please?

1) firstly, why did it burn inside and is this normal? I didn't vacuum the inside of the kiln before using as it was new. The outside of the kiln was covered in a white dust when I got it out of the box though. Have I ruined it?

2) What sort of rate should be selected for a hold temp of around 250 degrees C?

3) Once it had recognised the high temperature deviation, should it still have timed 15 mins for the hold time? I couldn't really work out whether it had just given up on the program completely after that as the temp kept dropping, I didn't see it stay around 250 degrees C for any length of time, and it didn't show that it had completed firing at any point.

4) Am I right in thinking that you can check the progress by pressing the down arrow during firing? When I did this, the display switched between "Idle" and the temp. Does "Idle" mean it has stopped working?

5) Does it matter that I turned it off in the middle of a program? I'm a bit scared of turning it back on again, but I'm desperate to put something glassy in there!

Sorry, about the long post. I probably just need some reassurance.

Thanks

All the best

Sam

[saffie]

Sam i am not an expert and someone else will help out more than me but it does not look major not sure about the technical stuff. The door and inside do get discoloured did you do an empty run before using it for the first time? I am sure Martin, Q or lee will be able to help you soon!
Hope it is ok!
Sam

[theseahorse]

Hi Sam,
Thanks for your reply. No I didn't do an empty run first. Should I have done? I suppose I thought that just putting a kiln shelf in without the glass was a sort of empty first run.

All the best

Sam

[Shirley]

Doesn't it say to do an empty run with the plug out of the top of the kiln the first time? I vaguely remember something.

[saffie]

Ah yes I did not read that bit Doh!!!! Maybe that is the answer just kiln wash! maybe i am no help at all :-\I hope it is ok does not look to bad, my bead door is a brown colour!!!

[beads-on-toast]

yup

mine is brown too - i think it's ok

Mine had a lot of smoke coming out too - i think it's the burning away of the top layer - but alas not an expert

[theseahorse]

Thanks for your reassurance girls. Shirley, I have had another look through the manual, but I can't see anything obvious that says that the first run must be empty. I have to admit, I was a bit confused about the plug and when this should be left in the top and when it shouldn't. The manual gives some instruction about removing the plug for a period during fusing, but I wasn't sure what to do with it when drying kiln wash and I can't see anything about what you're supposed to do with it when annealing beads.

Its a steep learning curve. I'll be glad when I've mastered the basic use of the kiln.

All the best

Sam

[Shirley]

It might have been a recommendation on here somewhere rather than in the manual, but I have definitely read somewhere about the first firing burning off any residue and the plug being out to allow it to escape. If I get a chance tomorrow I'll try to find the info

[theseahorse]

Thanks Shirley,
I appreciate that

Sam

[Lush!]

Yep, I'm thinking the same as the others.  I think the first fire can be a bit smelly and smoky but its not usually anything to worry about, and I think the discolouration is normal too.  As for the Htde error, maybe if you're only going up to 250, you need to go a little slower?

And Idle just means its not running.

[theseahorse]

Thanks Julie, that explains things. Presumably because of the overheating error, it just stopped the program then to cool down, I presume.

All the best

Sam

[Shirley]

And don't panic if you get the overheating error. If I ramp my kiln up on full it always overheats, so I ramp it up more slowly and it's absolutely fine. It's the difference between putting your brakes on when you get to the cliff edge and putting them on early because you've seen the cliff edge coming.

Have a read of this thread. Great information on here

http://www.frit-happens.co.uk/forum/index.php?topic=861.15

[turnedlight]

I actually spoke to a guy from Paragon, and said it would be an idea to change their sample program in the handbook to one which doesn't lead to overshooting errors, but evidently they haven't!

[flowerjasper]

i put off firing my kiln for the first time for ages!
i ran it empty with the bung out as it has to burn off "stuff"  i had a panic and threw out the matt that came with it as it went brown, i have a tile in the bottom now,
i used a batch annealling program from on here and have just put in a bead as you go program, i have never used the preprogrammed ones on the kiln,
good luck,
sandy

[theseahorse]

Thanks Shirley, Kathryn and Sandy,

The other thread is very useful. Do you think it would be wise now to run it empty with the plug out?

All the best

Sam