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Crack In Floor Of New Kiln


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#1 Isculpt

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Posted 29 October 2013 - 11:40 AM

After the first bisque firing to 06, I discovered these cracks in the floor of my brand new kiln. Is this normal??

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#2 perkolator

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Posted 29 October 2013 - 11:46 AM

some cracking is normal.  since your two cracks look parallel, i would question the type of support system under your kiln and would look to see if those cracks line up with the support stand underneath or not.  also, how was your stack setup inside?  lots of heavy work?  shelf directly on the soft-brick or with a spacer underneath?

 

i wouldn't really worry about it though since they look so minor and i doubt you can even see them on the other side of the brick.  personally, i just keep the floors of my kilns washed and don't really see any cracks :)



#3 Marcia Selsor

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Posted 29 October 2013 - 12:20 PM

Yes, I think so. It is settling. Possibly the floor wasn't perfectly flat for the kiln.
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#4 neilestrick

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Posted 29 October 2013 - 01:14 PM

Mostly normal, but slightly worse than I would expect from a first bisque firing. But it is a large slab, so it will crack more than a small kiln. Make sure the floor is sitting flat on the stand all the way around. No rocking or unsupported areas. Place sheet metal shims under the legs of the stand if needed. If the floor is not well supported then it will crack when the weight of the pots and shelves is applied.


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#5 Isculpt

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Posted 29 October 2013 - 01:18 PM

No heavy work was in the kiln, just a single layer of sculptures.  I used the shelf supports turned on their sides to support the shelves.  The one deeper crack in the first photo is directly over the support stand's legs, but the other is in the middle of the kiln, front to back.  I paid the kiln retailer to have the kiln delivered and set-up.  Should it have been leveled?  Would that have avoided this? And should I expect that the cracks won't get worse, since this is apparently "settling"? This is the kiln that was delivered to the retailer by Olympic with a big crack in the lid where the handle was screwed on.  (I  needed the kiln before Olympic could get another one to me, so it was delivered with the cracked lid and a promise from Olympic to send someone to my studio to replace the lid...eventually.)  I'm just wrecked by the cracks in my hard-earned first kiln, but apparently it isn't unusual or an indication that it's gonna fall apart??

 

So....here is where I mention that I also inadvertently left a plastic dish drainer leaning against the beautiful, shiny kiln.  It melted and left plastic and discolored metal on the kiln.  I've googled to see how to remove plastic from the metal, and the best suggestion I found was to heat it back up and use a plastic scraper to get the plastic off, then to scrub with nail polish remover after it has cooled down. Anybody else dumb enough to have done this?



#6 Isculpt

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Posted 29 October 2013 - 01:37 PM

And Neil,  There doesn't seem to be any rocking in the kiln.  (Of course, now that it has settled and cracked, maybe there wouldn't be any rocking? The floor is ceramic tile on cement, so that shouldn't be the problem....



#7 Mark C.

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Posted 29 October 2013 - 01:59 PM

What does the stand under it like like? is it fully supported?

As far as the plastic yes heat and scrape is best

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#8 Isculpt

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Posted 29 October 2013 - 02:56 PM

This is a picture of the stand under the 35"x25"x29" high kiln. The other image is of the damage I did to the outside.

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#9 neilestrick

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Posted 29 October 2013 - 03:04 PM

Just because the kiln is on tile or cement doesn't mean it will sit correctly. Cement floors are often out of whack, and tile even more so. I would check all the way around the stand and make sure the floor slab is contacting the stand everywhere it should be. If not, start shimming. The floor does not have to be level, it just needs to be well supported so that it can't flex, and therefore crack.

 

What hinge system is on that kiln? Does it extend below the top ring of the kiln?


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#10 Isculpt

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Posted 29 October 2013 - 05:05 PM

Neil, thanks for your time. I misunderstood your earlier statement "if the floor is not well supported" to mean the floor of the studio, as in a wood floor on inadequate framing. Sorry, I get it now. I've gone all the way around the kiln and the feet seem to be seated firmly on the floor. I then checked where the kiln meets the stand underneath and I can't slip a piece of paper between those points. If the problem isn't that the kiln is poorly supported, does that indicate a more serious problem?

The hinge is the kind that goes all the way down to the bottom ring, which is why Olympic will send someone to replace the lid. Apparently Skutt's hinge is much easier to take off.

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#11 neilestrick

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Posted 29 October 2013 - 05:13 PM

Actually, you were right both ways. If the floor of the studio is not perfectly even, the kiln stand will not sit evenly, and the floor of the kiln will not be supported evenly, resulting in the kiln floor flexing and cracking. But don't worry- hairline cracks are normal. That one near the end of the kiln is a bit more sever than I would expect to see in a first bisque, but that doesn't mean it will get any worse. As long as it doesn't crack all the way through and become loose, it's not a problem. Keep an eye on it over the next few months. But if the kiln is sitting evenly on the stand as you say, I don't expect it will get any worse.

 

That's a good hinge. I recently worked on an Olympic oval where the hinge was only mounted to the top ring, which could not bear that much weight and quickly crumbled. I was going to suggest some reinforcing if that was the case with yours.


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#12 Isculpt

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Posted 29 October 2013 - 06:47 PM

Thanks for the reassurance and advice to keep an eye on the crack. And that's good to know about the hinge since I'm kinda hoping this kiln will last me for a good long while!

#13 MikeFaul

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Posted 29 October 2013 - 07:01 PM

Good thread, I have the same issue with my kilns, but the cracks are not parallel. The floor is level and true, no separation or loosening of the bricks. We did fire a handful of large forms. The cracks were noticed after approximately 12 firings at cone 6.

#14 Mark C.

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Posted 29 October 2013 - 08:25 PM

It looks like the crack is on both ends where it leaves the stand support under it? Is this the case?

 

I like to support my whole bottom with a thick piece of sheet metal on top of stand under floor when setting up. I have always thought that most kilns are not supported well with undersized stands-That takes the wall stress off the floors.There has been a few threads on this issue

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#15 neilestrick

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Posted 29 October 2013 - 08:59 PM

It looks like the crack is on both ends where it leaves the stand support under it? Is this the case?

 

I like to support my whole bottom with a thick piece of sheet metal on top of stand under floor when setting up. I have always thought that most kilns are not supported well with undersized stands-That takes the wall stress off the floors.There has been a few threads on this issue

Mark

 

I think that's a great idea for larger kilns like ovals that only have a frame for a stand.


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#16 Mart

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Posted 30 October 2013 - 03:25 AM

You wrote "brand new kiln". What happened to the side of your kiln? (that huge stain of something corrosive)

#17 Stephen

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Posted 30 October 2013 - 10:33 AM

(whispering) she left a small plastic dish drainer leaning against the new kiln and it melted, she is trying not to think about it.

#18 Isculpt

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Posted 01 December 2013 - 10:27 PM

You wrote "brand new kiln". What happened to the side of your kiln? (that huge stain of something corrosive)

 

 

(whispering) she left a small plastic dish drainer leaning against the new kiln and it melted, she is trying not to think about it.

 


Hilarious!  I got overwhelmed by preparations for an impending show and didn't see these two posts until a month after they were posted!  I love the whispered reply....gave me a huge laugh!  By the way (whispering) you're right, Stephen, I am definitely trying not to think about it!!!!!  But really, it's funny how a tragic discoloration of a shiny new kiln seems inconsequential after a month of USING the kiln instead of standing there and admiring it!



#19 Stephen

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Posted 02 December 2013 - 02:52 PM

Glad I could provide a chuckle :)

I remember the first dent and crack. After shelling out 3 grand for the kiln, a few hundred to deliver and setup and a few hundred more for the electrician it started out as a shiny piece of equipment in our studio that I was sworn to protect.

My wife kept telling me it was 'just' a kiln, sigh.

Hey, how did the show go?

#20 Isculpt

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Posted 03 December 2013 - 11:46 AM

Boy, I get that whole "sworn to protect" thing.  I can't believe that a month after delivery, I have a couple of big ol' cracks in the floor and a huge discolored area on the exterior.  When I used the top of the kiln to dry some work while other work was firing, I got big dark splotches on the top and said "ok, that's it -- I'm through worrying about aesthetics!!"  Thanks for asking about my show, Stephen.  I've only been working in clay for 4 years, and this was my first show in 3 years. I sell my work through 2 galleries, but I supported myself doing shows for 20 years as a woodcarver until a fall wrecked my hand.  When I started tackling the issue of displaying ceramic pieces that are heavier and more breakable than wood, I got lots of help on the business forum regarding my booth display and lighting.  As you can see by the attached image, I haven't got the lighting down yet, although things looked much better when all the convention center lights were turned on. And the short answer (too late for short answers??) is that I sold 30 of the 40 pieces that I took -- which, for me, was a great show.  The work priced in the $150-$300 range sold better than the higher priced work, which is something to keep in mind for future fall shows, although maybe the bigger pieces were useful for attention-grabbing.

 

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