[Kiln over-firing due to cold weather?]

@High Bridge Pottery So, bearing in mind that I have no idea what I'm talking about, does that mean that the elements need more power than I can give them from the mains? It's not that they're worn out, it's that they're industrial strength (?) elements? I need to get new ones made up with a lower resistance? I hope I'm understanding at least some of this right...! Thank you SO much for all your help so far. 

[Kiln over-firing due to cold weather?]

@High Bridge Pottery I've measured the resistance and they're all the same (sides and bottom), around the 2/2.5 mark... the number kept fluctuating quite a bit but 2.2 seems to be a thing(!?) 

[Kiln over-firing due to cold weather?]

@High Bridge Pottery

As for the coils and the spaces in between the rotations, they don't seem to be very uniform. I just tried to measure the space between and they were all different and then seem to get more bunched up towards the back  I took some (really poor quality) photos to try and show the side vs. the floor:

 

Floor:       Walls: 

[Kiln over-firing due to cold weather?]

@neilestrick @High Bridge Pottery At the risk of being the cause of a few exasperated sighs and head shakes: most of this is going completely over my head. I am completely out of my depth...but also stubborn and ready to learn.

14 hours ago, High Bridge Pottery said:

Looks like an interesting kiln, is that just bare copper going in between the elements? Not seen anything like that before. What is that black box they are connecting to? 

I was worried you were going to say that. Yes, it is just bare copper (which even I thought was a bit odd) and, once I'd taken the cage off the back and cleaned it all up a bit, everything about it looks pretty old and tatty. 

I've tried to take some photos in sequence so the wiring might make a bit more sense:

        

 

and then some close ups of the two...er...connect-y thingies:

    

[Kiln over-firing due to cold weather?]

10 hours ago, High Bridge Pottery said:

I am surprised pottery crafts said they wouldn't do it, probably just being lazy as they don't have the specification on file.

The few places I know who would probably wind them for you are

https://www.kilncare.co.uk/elements

https://www.kilns.co.uk/kilns/kiln-elements

https://www.cromartiehobbycraft.co.uk/Catalogue/Ceramic-Kilns-Electric-Kilns-Pottery-Kilns/Kiln-Spares-Kiln-Elements/Kiln-Elements-Element-Wire-Connectors

This is brilliant. THANK YOU! 

Could cracks in the fire bricks cause the firing to slow down significantly? They don't seem to be going all the way through but there is a pretty big one running across the top and I've just found one down the back when I took the cover off to take photos 

Photos of the back:        

 

...and cracks:       

 

I have some high temp cement to fix these. Would it be worth trying before getting new elements or will it not make that much difference? 

[Kiln over-firing due to cold weather?]

@High Bridge Pottery Thank you so much for this. So helpful...and makes it all slightly less overwhelming.

My kiln does have four elements up each side and two at the bottom, with the bottom two having a bigger hairpin (...is that right?!) than the side ones. 

I did get in touch with pottery crafts and they told me I would have to find an element winder to make them for me specially. Am I right in thinking I can send the coils to someone for them to make something similar? Would I just need to know the correct voltage, if so? Thanks again!

 

[Kiln over-firing due to cold weather?]

On 12/20/2022 at 11:28 AM, PeterH said:

I suspect that the max temperature of 1300C means that the element life - when firing to your desired temperature -- is likely to be quite short.

This makes a lot of sense. I hadn't heard of this but, judging by the age of my kiln (and it looked pretty well used when I got it), it must have done a fair few firings. 

I knew this day was coming...I was just hoping I'd be able to get christmas out of the way first 

I'm going to give it a go, monitor the temperature and the timings and hopefully end up with something giftable... 

Thanks again for all the help!

[Kiln over-firing due to cold weather?]

On 12/20/2022 at 2:11 PM, Hulk said:

Looks like 1300 °C is well over Cone 10, excepting particularly (very) "fast" heating rates...

Am I missing something? I don't (aim to) fire to cone 10 or 1300C, that's just the top temperature on my kiln. I aim for a cone 6/1240C.

[Kiln over-firing due to cold weather?]

Thank you, @Bill Kielb! I think I actually understand that 

@PeterH My kilns plate: 

 

[Kiln over-firing due to cold weather?]

Thank you all SO much for your responses. All ridiculously helpful!

11 hours ago, Callie Beller Diesel said:

 I don’t start getting much slow down until about -25 or so, and even then, it’s only about a 15 minute difference.

My kiln has been about five hours slower so I think we might have found the issue! (About 16 hours to 21 hours)
I suspect the elements were already very worn when I bought it. I was just thrilled it switched on once I realised just how 'second-hand' it was. 

 

21 hours ago, PeterH said:

Did you previously fire by observing the cone drop or just use it as record of the firing?

 

I normally just use cones as a record of the firing. My kiln has one hole in the door and a bung for said hole which obviously expands and gets stuck once things start to heat up in there. If I leave the bung out to monitor the cones it takes even longer to get to temperature. 
(I posted a while ago about my kiln not reaching temperature and then realised I wasn't putting the bung in the door...oops!)

3 hours ago, PeterH said:

BTW -- assuming you have a controller -- what is the rate of your last ramp?

I normally put my kiln on full-whack for the final ramp. I do 150C up to 600 and then 999C (top temp on the controller) up to 1240. I'm aiming for a cone six but I still find the cone thing a bit confusing.

 

I'm starting to think I maybe better off replacing the elements before I even bother trying to fire again? It sounds like they might be beyond help.

Which leads me to my next issue: I don't think the manufacturers of my kiln exist anymore and no one seems to have heard of them anyway. What would I need to look into to choose replacement elements?

Thanks again! 

[Kiln over-firing due to cold weather?]

 

 

This is only about the sixth firing I've done with my kiln but it is verrrrrry old and a little worn out HOWEVER recently the temperatures where I live have been around -9°C (16°F ish) and my kiln has obviously taken a little longer to reach the desired temperature out in the shed/studio.

I forgot to put a cone pack in this firing but it's obvious from the results that something has gone a bit awry. Glazes that are normally very stable have become a lot more fluid (and ran off), underglazes have completely burnt away etc etc.

I don't really know what I'm talking about but is it possible that because it took so long for the final section of the firing to reach the desired temperature (1240°C/2264°F) that it was too hot for too long? And if so, is there anything I can do to counteract this? I stupidly decided to make all my christmas presents this year and, after the disaster of the last firing, I'm scared to do my final glazing with the crazy winter weather.

Thanks in advance! I hope at least some of this made sense.