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My Kiln Build

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Jed after you flip your bricks you could consider laying down a heavy piece of expanded metal.

I did this on my salt kiln-it allowed me to have more air space between support bricks. I used the longer bricks turned up (twice as long as yours) so kiln was taller (off foundation) and easier to load on the back.The super heavy expanded metal made a very firm layer for my hard brick layer before the soft brick layer.

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On our rebuild, we had a course of cement block, with another on top, followed by courses of soft brick (3") and hard brick (2 1/2"). Would have done 3" hard brick but we had to match the height of the flue that was left from the previous kiln. As we built, we did trial fits of kiln shelves and burners to keep us on track to the plans.

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Jed --  The pictures are of a salt kiln rebuild . . . the indented area is just behind the bagwall and will be filled in with a layer of castable so it is level with the rest of the floor.  That is the area where the salt falls in front of the burners and is where unvaporized salt pools on the kiln floor.  Basically, it is easier to replace the castable than hard brick.  A regular gas or wood kiln would not have that feature. 

 

The "8" on the bricks denote 80% alumina bricks -- which we used for the burner/salt port area; all other hard brick were 70% alumina.

 

The old kiln had two layers of hard brick for the floor -- 5" and was based on a design for a similar kiln built at Penland.  We went to three layers -- one soft brick and two hard brick -- on the advice of Will Baker, a NC potter and kiln builder/consultant.  I think he recommended 3" but we were dealing with the height of the existing flue and found 2 1/2" worked better. 

 

The rebuild is progressing; we will be putting the arch on next and doing cosmetic clean up, etc.  Cut more hard brick than I care to remember.  Your best friends are a level and carpenter's square.  The rebuild will result in a 2 stack, 14"x24" shelf kiln; the old one was 3 stacks (not by intent, though, but through miscommunication).  It has been a learning experience. 

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I agree with Mark. I used the longer blocks on their side. Also the added height makes it easier on your back.What castle are you using? If making your own beside to add at least 5% alumina for the mix on the outer surface to resist the slag. I like spraying soda ash from an old fire extinguisher or a garden sprayer with metal tip.It slows down the slag in the bottom..And doesn't corrode the burners.

 

Marcia

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Marcia -- we are using a prepared castable mix, not sure the brand but it is high-temperature.  We plan to spray the inside of the kiln with a glaze (not sure what type, maybe a shino or celadon) prior to the first firing to help prolong the life of the bricks exposed to salt vapors.  There has been no corrosion of the burners.

 

If this were my kiln and I was not tied to the pre-existing chimney and flue, I would build the floor higher for all the reasons you and Mark cite. 

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Jed floors get hot at cone 10 so a soft brick layer is what I would do as well. 4 inches is not enough-5 is a bare minimum. my salt kiln has a 3 layer floor .One of the layers is soft brick like the one shown.

I used fiber pads instead of the cartable inside bag walls where salt is added as they can break up and be replaced .

Also I do not use  much salt dumped in I spray it in mixed with hot water in garden sprayers. We do make a few soda tacos and toss them in (they are how water mixed with soda and poured into a paper form and folded up like a twice folded taco-then dried)I think it adds some color to the feet of the salt ware.

Mark

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it seems to clog the spray tips really fast-no clogging with strait salt solution-by the way that is a 100% solution until the salt falls out then add  a tad more water sieve and spray.

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I agree with Mark. I used the longer blocks on their side. Also the added height makes it easier on your back.What castle are you using? If making your own beside to add at least 5% alumina for the mix on the outer surface to resist the slag. I like spraying soda ash from an old fire extinguisher or a garden sprayer with metal tip.It slows down the slag in the bottom..And doesn't corrode the burners.

 

Marcia

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I have an extra supply of the 1/2 length cinder block.  So I took your suggestion and added two rows for extra height. I still need to trim every other end block to give me a smooth edge.  That will come on Tuesday as will the expanded metal.

 

Jed

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How strong is your dilution?meaning how much salt/soda say per gallon of water. I'm using a brass tipped garden spray want which I brazed the end on to take the heat.

I don't know. 

I start by adding salt/soda to tap water, stir and let it settle, add some more, settle, etc. 

When there is still solids after a couple of stir-settle cycles, I stop and filter it through a cloth filter and add some water to the batch to dilute it a bit. I want to avoid a "saturated" solution.  

 

I'm guessing the concentration is about 80-90 % of the chemical handbook solubility entry which I don't remember. 

I spray in short bursts keep the tip out of the flame except when spraying.  

 

LT

 

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Dry stack or mortar?  If I use mortar,  I was going to use fire clay and sodium silicate.  But, I don't know the amount of Sodium silicate, fire clay, and water.

 

Help!

 

 

Jed

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You can see my funky hard bricks..tongue and groove on the outer wall.

 

 

check list:

1.  2 burner ports 4" x 4" -----------outlet flue 4" x 8"........OK?  [ inner chamber 31" x 30" (foot print) x 24" (stem wall) with cast arch of 12" rise.]

 

2.  The floor has 4" hard brick base with 4 1/2" IFB above it.  That gives me an 8 1/2 inch floor.   I want to lay additional hard brick as a floor liner on top of the IFB.  Can I get away using s split brick layer or would 2 1/2" be better?

 

3.  I'm getting ready to make my sprung arch form.

        - how many inches wider than the kiln chamber width should the spring line be?  My kiln chamber is 31" wide.

        - I though about making the rise of the arch equal to the radius of the kiln chamber to decrease the need for a metal frame.  Is this a good idea?

 

 

Jed

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I'm at a out of state at art show  in Wa. with really sketchy internet so I'll comment in a few days when I get down Island to better service.

Mark

Ps your floor is plenty thick so yes on the thin layer of hard bricks-it only really needs hard in fire box and under stlit posts. and in flue area.

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