firebrick v cermaic fibre?

[mindy23]

Hey there,

Me again.  Wondered if anyone had an opinion on firebrick rather than ceramic fibre.  From what I can gather, firebrick kilns can have elements replaced relatively easily whereas its much more complex with ceramic fibre.  I have always used ceramic fibre but I wondered how firebrick ones are to run.  Are they more expensive and does it take longer for the beads to cool down in them?  I've heard that people with firebrick kilns can just shut them off an hour after a session and leave them to cool naturally as opposed to having a pre programmed ramp down.  Is that right or am I confused?  I was on paragons website looking at the Express series  and one of them isnt too much more expensive than the sc2, if it was an eaiser kiln to fix in the event of a problem I am tempted to go down that road....

My dog has started eating now on the brighter side, we will be sleeping on the livingroom floor with her tonight just in case she feels poorly through the night.  What a day!!!

Cheers all

Mindyxx

[Redhotsal]

Hi Mindy,
The general concensus is that firebrick is "better" overall in comparison to fibre. A firebrick kiln tends to be more rugged in construction (has to be to keep the bricks in place), whereas a fibre insulation is basically stuffed into a thin metal box. From this the firebricks are much better insulated and yes, you can turn off a firebrick kiln and the temperature will go down very slowly. A fibre insulated kiln will plummet like a stone. I know 'cos I have both types - and when the Paragon is accidentally turned off ('cos the controller is not very user friendly) I'm running around like a headless chicken trying to reset the programmer.
Looking at my Paragon Bluebird it would seem straightforward to change the elements as they are in the top of the kiln in a more solid part. The firebrick construction is very easy too - it looks as if you simply "unhook" the old element and insert a new one - this is a Potterycraft Aurora kiln.
One thing about elements is this:
On the Paragon Bluebird the maximum temperature is around 600 degs so the kiln is running very near its capacity everytime I anneal. The firebrick kiln - being a pottery kiln is designed to run at 1300 degrees. It's a bit like having a small car with a small engine and comparing it to a 2 litre Volvo. The Bluebird is going to pop an element so much sooner than the Aurora. It just is.
Secondly - never get batt wash or bead release on the elements of your kiln. It will kill them.
Thirdly - if you are a bit slapdash give the position of your elements serious consideration. If you poke a live element with a steel mandrel it is game over for the kiln and quite possibly yourself.
Hate to tempt fate but I've had the potterycraft kiln now for eight years and it looks like new, which is more than I can say for the Bluebird. The Aurora wasn't cheap - near the fat end of £700, but neither was the Bluebird cheap - £550. It's probably worth paying the extra in hindsight.
Glad your doggy is on the mend........

[mindy23]

Hi Sal,

Thank you so much for that.  I have been reading all I can find on the website but it is invaluable to get peoples real experiences, thank you for taking the time.  I feel that I am more drawn towards the firebrick as the price difference isnt too enormous.  When you make beads, how long does it take till they can come out?  Its the only thing I'm not sure of, is overnight long enough.  I normally work from 9-4 and then let the beads soak an hour and then start mt ramp down.  I collect them the next mornign and wondered if that would work with the firebrick.  I like to work each day if possible.

Thanks again, my dog is recovering from a hyseterectomy after a really bad womb infection.  I feel really bad for her as she has a giant wound and is feeling all wobbly after the anaesthetic and morphine.  I'm just so glad that she is at home to recover as its horrible to be seperated from them when their ill.

Thanks again

Mindy

[Zeldazog]

Hi Mindy

Not a lot to add to what Sal has said, I looked at both too - was looking at the Express range as an option (but as a fuser was concerned about uneven firing at the door)

One comment Sal makes about the Bluebird running at capacity - this isn't necessarily true of all CF kilns, SC2 goes up to 1000 degs, so that's not an issue.

CF heats up quicker, but does cool down quicker - more suitable for enamelling, silver clay, etc - but that's not to say you cant use a firebrick kiln for these.

I could be wrong, but Firebrick maybe cheaper to run than a CF - as firebrick is a better insulator.

CF kilns are a LOT lighter though - so if you're thinking of moving it around, it might be something to consider

As for time to cool down, I wouldn't say it "takes" longer - assuming the same rules apply for beads as for fused glass, then you don't want to go too fast anyway.  Thermal shock and all that.

Happy kiln shopping!

[Zeldazog]

Sorry cross posted there!

Mindy, in terms of my kiln, the full (fusing) programme takes about 11 hours - but that's from cold, a slow ramp up (which takes 3 hours for the first section) - a long bubble soak, then the process temperature and soak adds another hour at least - so the cool down section is probably only a five or six hours - and that includes the anneal as well.

My programme is very conservative (still new and getting used to it) - would rather go slow and be safe, as the heat up section in fusing is as important as the annealing - if you are only going up to anneal temp in the first place, you can get there much faster (it won't take four hours!) - certainly, your kiln would be plenty cool enough over night.

Incidentally, I use a Skutt Hot Start Pro, so a much bigger kiln - so, I am not speaking with direct knowlege of the smaller kilns - but I did lots of research before I took the plunge.

[Dennis Brady]

Ceramic fibre costs less and weighs less.
Brick works better and lasts longer.

[glassworks]

since we started stocking the firebrick bluebird it outsells the ordinary bluebird by 3 to 1.... it uses less energy per cycle, far less when actually at tempreture and takes all night to cool down when the power is off - it IS much heavier to ship, but it also has a bigger door and is taller inside...

if you are looking at firebrick versus fibre i have to recommend firebrick, we are changing both our older ordinary bluebirds in our own studio for the firebrick ones...

and, as a final bonus, the firebrick kilns have a far higher final temp - VERY useful for slumping, fusing or occassional pmc work...

[Lee - Kilncare]

Wow this one is going to bring out many differing opinions

The basic facts are as some of the posters her have pointed out.

Fibre weighs less, heats and cools quicker and obviously is less resilient to knocks. Fibre takes less electricity to heat up but more to anneal if the brick and fibre linings are comparable thickness of course as 6" of fibre will well be better than 2.5" of brick if you see what I mean,

Bricks are the opposite which would make the brick kiln the obvious choice.....

well not quite so simple....

bricks can have a nasty habit of occasionally dropping little crumbs even if they are coated, admittedly though it takes longer to happen when they are coated. If you don't believe me search the warm glass site in the states and there are a few threads where glass users are having crumbs of brick drop from various makes of kiln. I am bound to have replies from users saying theirs don't and I;m sure they don't, but at some point, most will. It is basic physics.
Fibre, if fitted correctly does not drop particles on the glass.

A poster mentions the Aurora, a kiln I know to the nut and pin! It is a ceramics kiln and so 600c is a canter to it as all of its parts will be close to 1300c rated. In my opinion it is correct that a kiln running at 50% capacity will last much longer than one running at, or near to full capacity. There is a mention that the SC2 is rated for a 1000c, well that is true, but the element is embedded in the insulation that is designed to not let heat through, so as you can imagine, the element does run hot as with any kiln of this type.
When the Aurora is 700c the element temperature may be around 770ish, on an SC2 the same temperature would see an element temperature of 900c +.

We rate our hobbyfuser at 960c but that is purely to protect the quartz heating tube, as the rest of the kiln, as with the Aurora, is made with close to 1300c materials, in fact, most are the identical materials.

Price is also mentioned but as is very often the case, you get what you pay for. 

As for changing elements. Not all fibre kilns are difficult to change the elements in. If the element is in a tube then it can be quite simple. If the element is set into the chamber or "muffle" as it is known, then you HAVE to replace the entire muffle.
We occasionally work on brick kilns where the elements are a complete nightmare to change, so, as you see, it is very much a case of if the kiln manufacture has built servicing into their design parameters or not. Whether it is a brick kiln or a fibre one, a lot of kiln makers seem not to consider later repairs.

As for sticking mandrels into elements.....don't get me started on this one again.  >:(Needless to say, as the Aurora is a compliant British kiln it is all but impossible to get electrocuted in this fashion when using the lid. We don't make the Aurora by the way.

[Dennis Brady]

Concerns about contacting mandrels to elements is why the new generation of bead annealing kilns have built in mandrel racks and the elements enclosed in quartz tubes.
http://www.vicartglass.com/products/products%20Kiln%20FLBK.html