[Clayart] Kiln with soft floor?

David Woof woofpots at hotmail.com
Fri Aug 30 21:44:20 EDT 2019

HI Snail, your always thoughtful responses......., backed by experienced knowledge.. you Snailed it...
I tend to think of a "breathing kiln" as over interpreted, editorialized nonsense of what the original "authority" had in mind when first published.   Heat always finds it's own outlet and if something goes out something else must come in to fill the void and I don't wish for chilly breezes, (spinning the electric meter,) during my firings.

So I get rid of the usually flimsy stands, Level the concrete pad or floor with dry from the bag fire clay and stack up concrete blocks on their sides for ventilation, Then lay a discarded steel Highway Stop Sign on the level block base and set kiln in place.

Steel Warpage is not a concern because Next I cut out a pad of refractory blanket for the inside floor.. followed by 3"X 3"  pieces of kiln shelf for foot pads to support each 1 1/2 " kiln furniture posts on which the first ware stacking shelves are set. This raises the first setting shelf slightly above the bottom element so that the first setting shelf is heated Top&Bot.  Thus and so, the pots don't have cold feet and subsequently immature glazes crusted in their well turned bottoms.

Of course the person who had the kiln floor sagging in areas most likely had the entire ware setting weight distributed on few posts with a narrow foot print and no post supporting pads.

***And setting a shelf directly on the kiln floor as the first ware setting surface is just creating a "heat sink" and is only "probably OK" for sculptural work where body and surface treatment maturation is not a critical issue, but where glazed ware for domestic utility may bring out crying but no cheese with the whine!

David................lost count of the kilns I've built, owned and fired,.... and the used, donated or purchased kilns, I've fired, wired and tested, refurbished, advised students and community members, and sold at cost to students who evidenced potential.

Shut it up now David before you start bragging about the thousands of pots, mouth watering glazes scintillating in summer sea sun, and the beautiful women and men who drink from my mugs and bowls, turned with well turned lips that bring hoarse exclamations of ecstasy and moans of delight!!!!
From: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of Snail Scott <claywork at flying-snail.com>
Sent: Friday, August 30, 2019 11:56 AM
To: Clayart international pottery discussion forum <clayart at lists.clayartworld.com>
Subject: Re: [Clayart] Kiln with soft floor?

> On Aug 28, 2019, at 10:55 AM, wschran at twc.com wrote:
> One clayarter responded adding a sheet metal bottom underneath the
> floor.Wonder if using a piece of expanded sheet metal might be
> better…

I know that some people have done this, and some manufacturers as well. However, it seems to me that the minimal rigidity of sheet metal, or expanded metal, is insufficient to give much support if the floor of the kiln is actually deflecting under load. Also, metal will warp when heated unevenly (as would occur under a kiln floor: cooler at the edges than the middle) and offer less support than when it was cold!

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