Rockland County, NY 36" build with pictures.

[stonecutter]

Re: Rockland County, NY 36" build with pictures.

Can you give your opinion which material is most suitable for an oven, castable or firebrick?

Firebrick has all the mystery and artistry of the craftsman to showcase, but is it just an "old material" waiting for a slow death? In the case of ovens only?

My opinion on most suitable for an oven? I would say whatever is available or affordable. There are pros and cons to every type of material, subject to limitations in use and design.

I lean towards firebrick or SS (dome only), mainly because unit masonry pre-engineers the cracking in the structure...and as mentioned, gravity and load force will hold it together in spite of it. The common weakness I see in cast or formed ovens (cob & adobe) is that the cracking can be controlled to a point with 2,3 or 4 piece domes, and reinforcement, but once it starts within those segments, the service life of the oven gets shorter every heat cycle.

I also do not consider firebrick to be antiquated at all. If anything, it will get better and better as time goes on.

I think it is the craft of Masonry that is dieing a slow death...for various reasons. That topic will derail the thread further so I'll leave it at that.

[stonecutter]

Re: Rockland County, NY 36" build with pictures.

At the temperatures we fire to the castable does not get sintered ie quartz conversion to make the clay content permanent. That change takes place at 573 C and its strength then increases as the temp rises further and vitrification begins.. Castable that has been fired to a high temp say over 1000 C is sintered and is much stronger rather than relying on the chemical bonding of the calcium aluminate cement alone. Do not fire your oven as high as you can go in an effort to try and sinter the castable because with wood firing the temp is too hard to control and the critical temp of 500- 650 C ,where sudden thermal expansion and chemical changes occur, must be taken really slowly. Over firing will just damage your castable or mortar with a WFO.My mobile oven is a case in point. When I hire it out I can tell if a customer has tried to see how hot they can make the thermometer go, just like a car rental over speed bumps, "Let's give this thing a thrashing"

Fascinating David...I wondered about any physical change at high heat, but I never heard or read anything regarding physical changes in refractory material. If you have any specific papers or articles you would like to share, would you PM me?

I would consider that the change in refractory composition after high heat (vitrification) to be a metamorphic one. And, the temperatures needed to bring about those changes do not create the bonding properties (like actual chemical curing ) but instead, greatly strengthen the ones that exist within the cured material.

I like the rental car illustration too!

[david s]

Re: Rockland County, NY 36" build with pictures.

At the temperatures we fire to the castable does not get sintered ie quartz conversion to make the clay content permanent. That change takes place at 573 C and its strength then increases as the temp rises further and vitrification begins.. Castable that has been fired to a high temp say over 1000 C is sintered and is much stronger rather than relying on the chemical bonding of the calcium aluminate cement alone. Do not fire your oven as high as you can go in an effort to try and sinter the castable because with wood firing the temp is too hard to control and the critical temp of 500- 650 C ,where sudden thermal expansion and chemical changes occur, must be taken really slowly. Over firing will just damage your castable or mortar with a WFO.My mobile oven is a case in point. When I hire it out I can tell if a customer has tried to see how hot they can make the thermometer go, just like a car rental over speed bumps, "Let's give this thing a thrashing"

[mikku]

Re: Rockland County, NY 36" build with pictures.

Stonecutter,
I guess we are both typing and responding at the same time!
Cheers, I think you answered the question.
Mikku

[oasiscdm]

Re: Rockland County, NY 36" build with pictures.

5thnaks guys found that discussion very interesting.

[mikku]

Re: Rockland County, NY 36" build with pictures.

Hello Stonecutter!

I am glad to hear you contributing on a topic that is important and you have a deep interest in!

Can you give your opinion which material is most suitable for an oven, castable or firebrick?

Firebrick has all the mystery and artistry of the craftsman to showcase, but is it just an "old material" waiting for a slow death? In the case of ovens only?

I know that your arsenal of materials include everything-stone, brick, block, old and new, handmade and mass produced products but I am sure you can give an unbiased opinion on the two!

Thanks for your always--on point observations and advice!

[stonecutter]

Re: Rockland County, NY 36" build with pictures.

Is that the difference between refractory and brick ovens? Refractory needs the curing fires to bring it to strength but the brick ones--the firebrick are already to strength and all you are doing is getting rid of the excess water?

Then why are all those brick ovens creating cracks during their de-watering process and mine is crack free during my curing fire?

Firebrick does not need fire to give it strength, neither does refractory material. A lot of variables and I have no time now, but it all has to do with moisture and the time it takes for the material to chemically harden.


The cracking of a brick oven usually has nothing to do with the material itself, but is the result of dynamic forces transferred into and through the masonry. These same forces are applied to castable, but the network of interwoven particles are on a much smaller scale than the brick. If there is a weakness in this microscopic network, you will see cracking. Eventually, ALL castable will crack, the questions are where and when.
Cracks (expansion) in a dome are not always an indicator of a failed structure either. The advantage brick has over castable is this unit arrangement. The mortar isn't really there to hold the structure all together, gravity and load forces can do that even with no mortar.

That said, to each his own.

[mikku]

Re: Rockland County, NY 36" build with pictures.

Ronwass you asked a question that is off thread, but I am glad to answer it--as long as someone doesn't jump into my crap.

Here goes:
In Japan, there are a whole lot of different method to build housing. The Japanese traditional was is called "zairai"- translated to English it means "post and beam construction". It is based on an old method of measurement using "shaku" as the base. 1-shaku is almost 1 foot. Really very close at 300 millemeters. Modern "shaku" is 303mm. Also "shaku" is divided into 10ths and each 10th is called a "sun" (soon pronunciation), and each "sun" is again divided into 10ths and called "bun". Most pieces in the structure are built with a multiple of shaku--floor joist sometimes 1-shaku spacing, Or 1.5 spacing (shaku-go-sun)---the method and measurements are confusing but only to westerners. Also sizes can be given in "ken" which is "6 shaku"- Which is also about the height of a person. But these dimensions have evolved over time and gotten bigger as the size of a Japanese person has increased.

Anyway, zairai is one form of building and is most used throughout Japan.
Usually zairai has posts placed on a 6 foot module (6-shaku) and on top of the posts are beams that can carry the weight of the structure above-either a roof or a second or 3rd floor. All the infill wooded members are much smaller- like 27 mm x the wall thickness- The wall thickness varies from 90mm up to 150 to 180mm depending on the structure. And sometimes, the framing members are actually round logs! Really a lot of variables!

Other building types are:
Prefab- or modular housing using wooden components
Prefab- or modular housing using steel components
Precast concrete
Steel buildings not prefab
North American 2x4 (but adjusted to Japan Standards)
North American 2x4 (same as framed structures in USA and Canada)

The final two are considered "import housing" and that is what I have been working with for the last 18 years. Prior to that I built housing in the USA for over 20 years.

Some of the young Japanese customers have a fantacy about USA housing, they believe that living in an import house is like living the American Dream. I do everything that I can to make that true. I build houses that make you feel at home in--comfortable, safe, and warm...in a structure that can take a lot more seismic forces than the traditional zairai house and is much warmer and comfortable to live in.

So, yes---in one way people are buying based on framing member sizes, but 2x4 is really a building style that utilizes north American sized building components. I help the customers get USA products to make their house American--like doors and windows, flooring, carpeting, linoleum, cabinets, siding, roofing, furniture, lighting, plumbing fixtures---you name it...I can source it from people that I have worked with for the last 18 years located in Portland Oregon and Seattle, Washington... they consolidate supplies from all over the United States and ship to Japan!

I have been working with Japanese tradesman and contractors showing them how to properly install and maintain the products that we import into Japan.

I'm just a piss-ant by comparison to the large importers and builders. But there are a lot of homes and happy customers that I have worked with over the years. I'm working here because I like working with my hands and this is an interesting place to live!

So, end of commercial--I didn't give any names and won't, didn't promote anything accept an American lifestyle--based upon a building technique called "North American 2x4 Platform Framing".

Don't limit products to be only from USA, we have imported container loads of "sheeps wool" insulation from New Zealand and that is a great "natural fiber" building product that has exceptional insulation qualities!

[stonecutter]

Re: Rockland County, NY 36" build with pictures.

Hey! Now both Stonecutter and Davids got me all cornfused. So when I was doing the progressively hotter and hotter fires what was I doing with my refractory mortar but curing it with fire?

Material like mortar, castable refractory, concrete, etc,etc, cures through chemical reaction, absorbing carbon dioxide and moisture evaporation. Some material, depending on it's contents, cure faster than others. Faster setting material creates it's own heat. Even using warm water in a mortar mix will speed cure time ( not a good thing )

Firing uncured masonry obviously creates more heat than the naturally occurring chemical reaction. Driving out moisture is good for firing during use, as we all know, steam can be damaging through pressure.

Firing the masonry before it is cured weakens the material, because it needs to be completely hydrated in order to achieve maximum strength.


Time puts practice to the test...a few months of use does not. And, understand I am not saying anyone did anything 'wrong'...you may not see any cracking for a long time. But the margin for error goes up drastically if you do not fully cure material containing portland cement.

[mikku]

Re: Rockland County, NY 36" build with pictures.

Hey! Now both Stonecutter and Davids got me all cornfused. So when I was doing the progressively hotter and hotter fires what was I doing with my refractory mortar but curing it with fire?

Is that the difference between refractory and brick ovens? Refractory needs the curing fires to bring it to strength but the brick ones--the firebrick are already to strength and all you are doing is getting rid of the excess water?

Then why are all those brick ovens creating cracks during their de-watering process and mine is crack free during my curing fire?

Yep! still a newbie--please make the point clear!

[david s]

Re: Rockland County, NY 36" build with pictures.

It is not contrary to anything, it is advice. My reply was to something in post 149 about fire curing mortar. Mortar should be cured before firing the oven, so that it can reach maximum strength. Firing an oven after that isn't really 'curing' in the true sense of the word,...you are ridding the masonry of moisture.
Sorry for the confusion.

I totally agree. The term curing fires is misleading. I prefer to refer to it as "driving off the moisture". I've suggested this change in "recommended changes" but maybe the term is so ingrained that they don't want to change it.
To cure cement products you hold the moisture in (hydration process), but then to cure the oven you drive the water out, most confusing.

[stonecutter]

Re: Rockland County, NY 36" build with pictures.

I'm curing the oven, I'm curing the oven. That's the exact word in the book. Mortar has been curing for many many days now without heat. Kept it moist, etc, etc, etc. etc

The book is a very good oven guide, but many masonry terms and techniques can be and are confused. I addressed a specific term...I didn't say you did anything wrong.

[ronwass]

Re: Rockland County, NY 36" build with pictures.

I'm curing the oven, I'm curing the oven. That's the exact word in the book. Mortar has been curing for many many days now without heat. Kept it moist, etc, etc, etc. etc.

Also, Mikku, people in Japan actually ask for a specific size of stud in the construction of their houses?

[stonecutter]

Re: Rockland County, NY 36" build with pictures.

Now, what does that mean? I'm just following the book about the curing fires. Chapter 17, page 65. Everybody does it around here. What are you saying?

What is this contrarian talk?

It is not contrary to anything, it is advice. My reply was to something in post 149 about fire curing mortar. Mortar should be cured before firing the oven, so that it can reach maximum strength. Firing an oven after that isn't really 'curing' in the true sense of the word,...you are ridding the masonry of moisture.

Sorry for the confusion.

[ronwass]

Re: Rockland County, NY 36" build with pictures.

Mortar should not be cured by fire.

Now, what does that mean? I'm just following the book about the curing fires. Chapter 17, page 65. Everybody does it around here. What are you saying?

What is this contrarian talk?