Fireclay in Japan

[khpizzaovenguy]

Re: Fireclay in Japan

Hello again,

We'll the party was successful, three turkey's, several loaves of bread and quite a few pizzas.

The sandbag experiment was almost a complete flop. We failed to calculate dynamically for the efficiency of the vermiculite as insulation. After the mass so the bricks and fire clay heated up, the bags started melting. The vermiculite poured out onto the ground. Quite a bit stayed on the dome, though. For the turkeys, we built a fire on one side of the dome and placed half a dozen firebricks through the center of the dome and slid the turkeys in on the other side. In about two hours, we had three nicely done turkeys. After letting them settle for about a half an hour, my son carved them. Suberb!
Dann

[Toomulla]

Re: Fireclay in Japan

Should have read the reply from Mikku

[mikku]

Re: Fireclay in Japan

Hello again,

We'll the party was successful, three turkey's, several loaves of bread and quite a few pizzas.

The sandbag experiment was almost a complete flop. We failed to calculate dynamically for the efficiency of the vermiculite as insulation. After the mass so the bricks and fire clay heated up, the bags started melting. The vermiculite poured out onto the ground. Quite a bit stayed on the dome, though. For the turkeys, we built a fire on one side of the dome and placed half a dozen firebricks through the center of the dome and slid the turkeys in on the other side. In about two hours, we had three nicely done turkeys. After letting them settle for about a half an hour, my son carved them. Suberb!
Dann

Glad to hear the party turned out well. You never said how you were going to do the bread...

Since you had some problem with the plastic sand bags, there is something else that I have experienced with other hot objects..

A few years ago, I was operating a compactor with a gasoline engine on it. It began to rain and I quickly threw one of those "blue tarps" that you can buy anywhere for very cheap. The muffler was still very hot and the tarp melted onto the muffler. Now even two years later, when I use the compactor there is always a residual odor of burning plastic. I have to look around to see if something is on fire, but then I realize it is the residual plastic on the muffler.

So.... you should be very careful to remove as much plastic (if melted onto your dome)--even if it requires using a wire wheel on an angle grinder to get it off... OR I think that you will have the smell of melting plastic linger for a very long time!

I would have been much better off letting the compactor get a little wet! The engine was still very warm, other objects hot... what little rain that hit it would have quickly evaporated and I would not have this sweet stink every time I start the engine.

So now that the Christmas party is behind you, what is the big plan for the "New Years" baking, roasting, activities for the WFO?

[khpizzaovenguy]

Re: Fireclay in Japan

At this time, no plans for the oven during the NY holidays. We had over 40 people here and are still recovering. also, we have to spend some time in Tokyo with family and friends.

After returning we will begin cleaning the outside of the dome and putting on the vermiculite. We are also planning to add a BBQ grill to one side of the oven.

Also, I am working on my workshop so I can open my DIY classes in April.

Dann

[mikku]

Re: Fireclay in Japan

I know absolutely nothing about fireclay and sand but can you explain something?

When you mix fireclay and sand, it is only a kind of silt and sand ... (and river sand is has rounded edges rather than angular) right?

Does the heating of your WFO get hot enough to turn that mixture into something like pottery? Or is the temperature too low so that it is only clay and sand ...thus making it susceptible to damage from normal rainfall and water intrusion?

And, if it turns into a type of pottery, then why use firebrick at all in the construction of a WFO---instead only use the sand and fireclay?

Maybe a dumb question, but other builders use some kind of a homebrew with fireclay, lime, Portland cement, sand and whatever.... I don't know!

How about enlightening me?

I chose to use a castable product manufactured by Asahi that had special characteristics that withstood high temperatures and set up quickly. When I calculated the volume cost of the castable vs firebrick, the cost was virtually the same--so I cast everything.

Item #2: What kind of DIY classes will you be teaching?

[khpizzaovenguy]

Re: Fireclay in Japan

I'm not completely sure of the fireclay composition, but in the oven when the temp reaches about 600 C, the fireclay begins to fuse. The fire brick also do the same, but only for a couple of mm into the body. At long exposures to very heat, say 1200+ C, the entire mass will turn ceramic. It is hard to get that kind of heat in the oven. My pottery friend uses firebrick and fireclay in his kiln. He raises the temp to over 1350 C for several days to make pottery. The interior of the kiln looks like greenish glass, but it's only a few mm thick.

My DIY classes will focus on helping people learn basic tool usage, common safety practices and creating (relatively) simple projects of their own design for their own needs. I will be showing the students some of my own work in progress as examples. I plan to conduct classes in a mix of Japaneae and English for those who wish to expand their language abilities.

Dann

P.S. I am working on getting photos ready to post here. dg

[mikku]

Re: Fireclay in Japan

I'm not completely sure of the fireclay composition, but in the oven when the temp reaches about 600 C, the fireclay begins to fuse. The fire brick also do the same, but only for a couple of mm into the body. At long exposures to very heat, say 1200+ C, the entire mass will turn ceramic. It is hard to get that kind of heat in the oven. My pottery friend uses firebrick and fireclay in his kiln. He raises the temp to over 1350 C for several days to make pottery. The interior of the kiln looks like greenish glass, but it's only a few mm thick.

My DIY classes will focus on helping people learn basic tool usage, common safety practices and creating (relatively) simple projects of their own design for their own needs. I will be showing the students some of my own work in progress as examples. I plan to conduct classes in a mix of Japaneae and English for those who wish to expand their language abilities.

Dann

P.S. I am working on getting photos ready to post here. dg

I am surprised that more people have not checked in on your build. A big part of it is "photos" --seeing something helps with the understanding part.

Davids is an educator with a whole lot of side activities, Brickie is a lifelong mason, oven builder, author, and one time furniture maker. There are a lot of other talented people who enjoy preparing almost anything in their ovens...some specializing in bread making only.

It sounds like you will be able to blend your hobbies and teaching background into something profitable and enjoyable.

Most Japanese that I encounter have a very good background in English grammar and composition but lack the confidence to converse --maybe the casual atmosphere of DIY projects will allow them to learn easily. The acceptable system of teaching English in public schools seems to be a failure.

Only thing I remember of ceramics is from high school art class--made an ashtray... With today's non smoking policies, that work of art would have warranted an "F".

[khpizzaovenguy]

Re: Fireclay in Japan

Hello,

As mentioned above, I am attaching a photo giving a rear view of the oven after the chimney was completely installed. No insulation on it at the time. Eventually therehwill be partial walls on three sides.

Dann

[khpizzaovenguy]

Re: Fireclay in Japan

Well, it looks like I still have some fiddling to do. The photo in the previous post so upside down!?

Dann

[david s]

Re: Fireclay in Japan

I know absolutely nothing about fireclay and sand but can you explain something?

When you mix fireclay and sand, it is only a kind of silt and sand ... (and river sand is has rounded edges rather than angular) right?

Does the heating of your WFO get hot enough to turn that mixture into something like pottery? Or is the temperature too low so that it is only clay and sand ...thus making it susceptible to damage from normal rainfall and water intrusion?

And, if it turns into a type of pottery, then why use firebrick at all in the construction of a WFO---instead only use the sand and fireclay?

Maybe a dumb question, but other builders use some kind of a homebrew with fireclay, lime, Portland cement, sand and whatever.... I don't know!

How about enlightening me?

I chose to use a castable product manufactured by Asahi that had special characteristics that withstood high temperatures and set up quickly. When I calculated the volume cost of the castable vs firebrick, the cost was virtually the same--so I cast everything.

Item #2: What kind of DIY classes will you be teaching?

Clay turns permanent at 573 C and anything north of that will make it harder. This process is called the alpha change or sintering. This sudden change needs to be done very slowly as rapid expansion takes place at around these temps. The firing schedule of your castable provided by the manufacturer should confirm this. Unfortunately it is not possible to do this with wood. The danger zone is actually 500 -650 C and the crown of the dome and other parts of the oven at the surface is likely to go in and out of this temp range quite quickly, probably every time the oven is fired. Fire bricks are fired slowly through this range and well beyond, up to much higher temperatures making them stronger and more stable.

[mikku]

Re: Fireclay in Japan

Well, it looks like I still have some fiddling to do. The photo in the previous post so upside down!?

Dann

With all the year end activities, parties, consuming alcohol more excessively, your picture looks just fine! Do you have any views of the other sides?

I finally got my oven outdoors again and elevated into its' final resting place. Had a lot of trouble with borrowed equipment; actually ended up borrowing two forklifts and a UNIC boom truck. Borrowing is great to get the job done but payback is a bitch. Two large -- fully loaded pizza's for one forklift and boom truck; overhaul a chainsaw for the other forklift! Wonder why nothing gets done at my house?

Really thought I'd get more done over the New Years' break, but this time of year is full of interruptions!

Last two days, bread baked twice, one baked hot dish, BBQ baby pork ribs--once all the extra insulation is in place, oven should really hold the heat.

Started a fire with twigs from a downed pine tree; added a few chunks of oak, added another chunk of oak at 11:30AM... Cleaned the oven at 2PM, at 4 was still too hot 300C, took the door off for an hour ...after closing again read 230C---put rye bread in --added steam...after 15 minutes the top of the bread was burnt slightly and the oven read 280C!

Bread was done inside and tasted great! Way--Way too hot...need to get used to times and temperatures again!

Just checked a few minutes ago---still 250 and its been 7 hours since I took the ashes out of the oven!

[khpizzaovenguy]

Re: Fireclay in Japan

I am going to try to post another pic. This one shows the front of the oven.

[mikku]

Re: Fireclay in Japan

From what I can see, it looks like you have your chimney starting inside the dome and use a damper to close off when you need to bake. Is that a correct assumption?

What is the next step you are planning for the oven? Installation of the pericrete insulation layer? / ceramic fiber chicken mesh and pericrete? Then you mentioned something about three partial walls...

Is the colder weather delaying any of your oven completing plans?

[khpizzaovenguy]

Re: Fireclay in Japan

Hello,

Yes, the chimney begins just inside the panel that defines the top of the door. The chimney is simply a 150mm stovepipe that continues out through the roof. I'm attaching a picture of the flame pattern in one of the curing firings. When the fire and oven are quite hot, the flames reach nearly to the floor on the opposite side of the dome.

We get plenty of draft, probably a function of the length of the chimney.

We hope that we can get started later this month putting up more of the clay (about 5 cm.), followed by the vermiculite concrete (about 20-25 cm.with a chicken wire armature to help support it as it dries. The final coat will be white mortar as a cosmetic finish.

Hope the weather won't impact us too unfavorably. We will wrap everything in blankets and blue sheet to keep frost out each night.

Walls: On three sides of the roof structure, there will be walls running from about 40 cm above the ground up to about 2 meters. I already put in one of them on the side away from the oven, but will need to re-design as it interferes with using the peel when loading and unloading the oven.

[mikku]

Re: Fireclay in Japan

Looks like the fire is roaring and putting out the BTU's, also the interior brickwork looks great.

I've been building an outside structure for my oven and decided against a masonry base entirely. The enclosure is 2275mm, wall center to center for width and 2730mm depth from front to rear (the space for the oven). The oven weighs about 1.25T in materials and is supported by 3- douglas fir beams 180mmx105mm beneath the oven. six places for support so each leg supports only 460 pounds. Should not have any problem with these beams and the entire space under my oven is open --for whatever use!

This space is part of a larger structure that will hold my supply of firewood for our woodstove in the house and the WFO.

My current plan is to apply one more render coat with a vent at the top of the dome, then build some walls on each side of the slab extending maybe 8" above the highest point of the dome and place loose fill vermiculite into the void. The thickness will vary from 6 to 15" thickness. The oven already has 100-150mm thickness of pericrete as insulation already.

When the entire assembly is complete, I only need to do a nice job on finishing the face of the oven--all other surfaces are of no importance. This should really hold the heat in!

The next issue to tackle is my chimney height. The rule of thumb for chimneys is to be 600mm above the nearest roof that is within 3 meters- measured horizontally. I might end up having a pretty tall chimney because my house is very close and the roof slope is severe 8/10 pitch. or slope whichever term you want to use.

Every day--fun and games!