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Mark C.

Salt Kiln Conversion

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Making due with what you have on small island  is what this is all about.

I say this because there are zero ceramic supplies here.

I'm converting this large oval to a salt kiln with what I sent over and what they have here already.

I did not cut the burners into this-it was done before I arrived. I would cut them about 3 inch up off floor so the floor could be full  hard bricks for salt corrosion . This meant a few piping changes but would add life to kiln.The kiln was stripped of all elements and electrics. It was donated from Maui and shipped over for 80$. It now propane powered.

I shipped over 12x12 old 5/8 thorly shelves via the large flat rate usps boxes

I first sprayed kiln  and lid with my own special salt coating-witch is high in alumina and contains kyanite and zircon as well as a binder (Let call this coating A) then coated with 2/3 alumina and 1/3 epk by weight(lets call this coating B)

I cut with a dry diamond skillsaw blade the shelves to fit floor and coated both sides of them-laid a 1 inch layer of fiber on floor to soak up salt lava and laid floor on top.

I cut two salt ports in front of kiln (with brand new 4 and 1/4 inch hole saw)and coated with my already posted zircon colloidal silica sauce with makes a very hard surface than coated this with the B coating

I cut the salt ring  port (with my Makita Oscillating saw) and added a split brick port in upper ring and coated that all with A&B coatings

I moved the lid handles and reattaches them with stainless screws so two people can lift it opposing sides.

Yesterday I cut the fiber piece that I will line whole kiln with.

Do do list still

-line kiln with fiber and attach with buttons

Line lid and attach fiber with buttons

Since this is an oval and the shelves we have do not fit that end shape well and I only have enough to use at one end I'm building the chimney inside the end of kiln with hard brick. This will come thru a hole cut in lid near edge. On top of lid after we load it we will have a stack of soft bricks and a damper. I'm choosing this design over a updraft for better salt distribution .Also we have a pile of old soft brick.Hard brick are in short supply here-I sent some stilts over and cut hard bricks for posts.I will cut the lid hole with my Makita Oscillating saw -its great in soft brick cutting as its so precise.

I shipped over a few large flat rate boxes of tools via USPS.

Cutting the stainless bands is brutal on blades so use at least bi-metal ones-I killed my 4 1/4 inch one on the two holes.

There still is a small hood and metal stack to suspend in metal shed to install.I had some pipe sections dropped off via an art center person who flew from another island with a Home Depot since there is none of that her and it takes a month to oder it.

I'm still waiting on a box of hard brick splits and a tub of kiln mortar to do the internal chimney 

Still need to add the ceramic protection tube for  digital pyrometer

We still need to have some wielding done on the angle iron to make Them longer with some rebar to introduce salt.

I'm going to add some fiber pads to floor area where salt is dumped in like diapers that need change between fires to add some life to this kiln.

The trick is keep the salt lava from eating thru the floor and you must keep coating and adding new fiber diapers each fire.

The fire is next weekend.







Edited by Mark C.

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Today my wife and I fibered the interior

I like to make button gaskets out of delaminated  fiber about 1/2 thick

You need to add loft to the job as the fiber will shrink at cone 10 no matter what its says on box-I tend to add this loft in two directions .

I made these buttons and shipped them over.

I use these pliar's to make the pig tails which keep tension on the button.The gaskets keep heat off the wires and add life to job.







Marcia Selsor, terrim8, Min and 3 others like this

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Waiting on a tub of mortar and some split bricks to lock up internal chimney bricks-then cut hole (flue in lid then fiber lid and spray all fiber with salt resist.

Add some makeshift bag walls -cut a few shelves to fit front-add damper load kiln -add lid build stack and add metal chimney on top.-still a lot to do.

We need to add in some vacation  down time. Its been 10 days now and only 3 swims in ocean.We have 20 days left here.

terrim8 and Marcia Selsor like this

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I got a swim in today .

A friends brand new front loader electric got dropped while installing here and I worked on that some today as well. New brick pieces cemented in place and will face some areas after sanding smooth.This should go smooth as its not damaged much.

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Good pictures! Now I know to make the gaskets bigger than the buttons. (for my raku kiln) If I could figure out how to make an inexpensive door for my caternary arch kiln I would turn it into a salt kiln too- right now I brick it up with two rows of bricks. The sliding doors at the pottery in Med Hat are HEAVY so I don't want to do that.  You aren't giving out the secret sauce recipe are you?


Edited by terrim8

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Finished the kiln yesterday .I put in a 8 hr day but got it done for Saturday . Glazing and Sunday fire. Th plan is this weekend and if we have enough  pots next weekend same schedule.

I'm making do here with what I have. The stack is about 20 inch of piled soft brick with a damper on lid-this gets installed after loading pots in kiln and on top of lid. Then its 10 feet of sheet metal the top ,5 feet is aluminum 8 inch diameter metal pipe to bottom 6 feet is single wall 7 inch galvanized stove pipe jammed inside old rusted 8 inch single wall pipe .A  art center member had to fly this new pipe over from Oahu with her .(nothing like this on this Island) This will get eaten up fast-maybe two fires ?-I coated the inside with the usual 50% alumina Hydrate and EPK which is the standard wash on shelves and most kiln parts -except fiber. The brick pile is the damper -not much but it works.

The stack counting the inside and loose bricks and metal is about 13-14 feet tall.

I'll take some shots on load in day. The space is only 15x20 shelves-about 30 inch tall..

I gave a salt  lecture to small class along with my friend who runs the center yesterday about salt (12 adult students)

I have spent much of  the past two weeks making this and now ready for other things-We are taking a few days off.

The unusual part for me is I will be gone when this kiln gets unloaded as Sunday is the  fire and We fly down to the Leper colony (Kalaupapa) for 4 days volunteering with the National Park service Early Monday morn. We come back topside Thursday afternoon and it will be unloaded.Never in my ceramic life have I missed a kiln I fired to unload-its an unwritten code for potters but I'm ok with it as its the schedule I was dealt.It will make the next fire a bit harder as that knowledge will be lost for me.I asked for some photos.






Edited by Mark C.

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Today we glazed about two loads ,dried the kiln at 800 degrees for awhile(candled) then loaded the kiln got the lid on it. I still need to add the damper and marry the stack of bricks (chimney ) to metal  stack in am. Tomorrow we fire this design. to cone 10 .The shelves are 20x15 and 20x 16 and I used  4 shelves . The pots in photo that are glazed and waded  are on the lower two shelves and floor to be loaded.I got more than 1/2 of them in this first load . I will be away during g unload mid week so I will not have photos of kiln unload-sorry. I will have photos next week of land two if it goes as planned. I have never done this design and am working with what I have.I am hoping for a miracle on MOLOKAI







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Unloaded the 1st salt fire yesterday -fiber was damaged as expected in firebox areas-it may last 1-3  ore fires before that layer gets taken off.

Top shelve was cold-we put 40#s of salt in via rebar method .The fire was mixed bag-some great some not so great some blaaa.

Today I load another load and will stack it so flow is better to the top. Will fire with less gas as well.








terrim8 likes this

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Really HOT Mark, strange, this weeks quiz comes from Colson's Kiln Building with Space-Age Materials. Yeah I know probably out of date to some degree, but the basic principles are there.




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Fired my second fire today in  salt kiln-10am to 8:15 Pm.. Just like last Sunday except the land was only 2 shelves of pots -bigger pots. The kiln took a beating the 1st fire especially the fiver in the firebox areas . I added more fiber -replaced the firebox floor diaper fiber that salt gets dumped on. There are some serious holes in wall fiber now. we will see come Tuesday how the second salt does to interior .Today we fired much slower and did it with less than 10 gallons of propane . It was early sipping gas as it was turned so low.

I think the bag walls need to be taller. for better upper flow.I will suggest this this to next crew to fire it.

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Ok todays fire was spectacular -top got hot and salty. All where very happy.

The downside is my fiber liner got toasted and was ripped out after unloading. Now the next fire will be just the 3 inchs of coated soft brick.Fiber really even coated does not want to be dumped with salt.

I'll post some photos when I have time.


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