engineering brick for dome

[Miker]

Can I say first, what a fabulous forum this is, great questions and patient,knowledgable and understanding answers.My question is: could I use engineering brick for the dome? I live in London UK, I have been quoted ?3.20 for fire brick, happy to use that on the hearth but engineering brick is about ?0.70. I am looking to build a 36" to be used for bread and Pizza, probably fired twice a week, if anyone knows of cheaper firebrick supplier in the UK would be gratefull for info.

Miker

[james]

Miker,

Welcome aboard. Your plans sound good to me. My wife (London as a child, Cambridge for work) has alway said that she thinks brick ovens are the perfect way to extend the English seasons. I am guessing that Alf will have an opinion on this. He's in the lake district and knows as much about brick ovens as anyone.

Over ?3 for a firebrick seems pretty steep -- perhaps they are high duty bricks for industrial applications. Low-mid duty firebricks are a little over $1 in the states.

How would you describe an engineering brick? How much is a basic fired clay brick?

James

[Miker]

James. Thanks for your reply, your wife is right about extending the season here in the uk, I love the idea of a chilly day with good friends,wine and sharing good honest simple food from the oven I fell in love with brick ovens while on some occasional trips to Nice, France 25 years ago, and frequent biz trips to Italy. It was very visual there, with the oven at the the front of the restaurants. It is sensual, magical and has something of the alchemist about it.Here I am married with two teenage children and the dream wont go away.Sorry I digress.
Engineering bricks here are a very dense water and frost resistent brick used for Victorian railway arches and below water line and damp proof course use. density is about 3.3kg for a standard brick 215 ? 102.5 ? 65mm. Tom Jayne uses them in his oven for the dome, I have not been able to find any thermal transfer details for them yet, perhaps they may not hold the heat as much as fire brick. I would be interested as to whether Alf will have any views

Miker

[james]

Miker,

While there are definitely wood-fired ovens in France, the Italian ovens are much nicer. We ate in a small Pizza and Moule Fritte restaurant a couple of times in Provence last summer -- the mussels were great, but the french pizza chef had a few things to learn. The oven was wood-fired, but they had a way to go.

If Tom Jayne used the engineered bricks, I would guess that they would work. The Pompeii oven design is much more efficient than the oven described in those plans, and will work well. My only idea is that there might be something a little better for not much more cost. A low-mid duty firebrick is +/- 30% alumina and 50% silica in the states. A basic red fired clay brick, of unknown makeup, costs about $.45 at Home Depot. Can you find a basic clay brick at B&Q?

One way or the other, you are off on the right foot.

Let us know where it goes.
James

[Miker]

Thanks James. Through your wonderful forum you guys had convinced me to make a round oven. I have had Tom Jaynes and Alan Scotts book for 5 or so years as well as an early book by Poilane which showed a round oven. but the forum has demystified about 95% of it. On the issue of bricks, are you saying that a common, quality, high fired red house brick will do? or am I mistaking the terms used in the US, I will check on the make up of what we call red brick. listened to your podcast last night really good, heard you lived in San Gimignano for while, My wife took me there for my birthday a couple of years ago in late May, it poured with rain every day except the day we left, but the stunning medieval architecture made it an amazing place.
Regarding French food,there is a sort of myth that it is always good, the truth is you can generally eat much better in France than a lot of European countries I have had bad food in France and bad pizza in Italy, but rarely.
Regards all
Miker

[james]

Miker,
I'm still getting over having to leave San Gimignano. We had a house inside the walls with a nice garden, a garage (!) and pizza oven. I guess all good things must come to end.

Back to the bricks. You can get by with a clay brick in the dome, but my experience is that the firebricks perform better. I'm still trying to understand where the engineered bricks fits in.
James

[Miker]

James. I am probably confusing a few things in my own mind. when I am thinking about the bricks for the oven, in my mind I have a vision of this brick having to take thermal shock,resist frost and capable of acting as a thermal sink.An engineering brick(probably a misleading term dating from the victorian era)is usually a blue/black, smooth surfaced, incredibly hard dense brick. It retails here for about ?0.70,clay brick is about ?0.35 I have just located firebrick at about ?1.25. I dont want to get too pedantic,after all I am sure the Romans did not have perfect bricks, but they all had a lot of slaves to rebuild if things didnt work out. my thinking is that this hard brick is probably going to be good for the dome, but I will use fire brick for the hearth. but I will try and persue cheaper prices for the firebrick first.
Regards

Miker

[Alf]

Hi,
Sorry of the delay in this reply Miker. Engineering bricks were certainly used in oven construction throughout the UK during the late 19th and early 20th century. As we see throughout our landscape engineering bricks do hold up railway arches so there strength isn?t a question. As for withstanding heat that?s not a problem they are fired way beyond the temperature that an oven will get to. The problem with them as against firebricks is their ability to store heat, they just aren?t as good.

So go with firebricks if your still looking for firebricks try these folks:

http://www.purimachos.demon.co.uk/index.htm

http://www.handsworth-refractories.co.uk/new+stock.html

http://www.yorkshirerefractoryproducts.com/contact.htm

Let me know how you get on

Alf

[garyni]

Re Fire Bricks in the UK

Re Fire Bricks in the UK.

John Hall Refractories Ltd http://www.livingnet.co.uk/JHR/location.htm quoted ?0.91 ex VAT per brick with delivery @ ?30.

Handsworth Refractories http://www.handsworth-refractories.c...ire_brick.html quoted ?0.85 ex but a higher delivery charge @ ?60.00

The bricks from both companies were 38-42% Alumina.

Cheers
Gary

[jengineer]

Wow

talk about a great first post!

Welcome aboard Gary

[dmun]

it is pricey in the UK

I just got the same quote in US pennys as you got in UK pence.

[peterbennett]

Re: engineering bricks vs Fire Bricks

Hi all,

I am just sizing up the pompei oven as my next project and noted the discussion in a number of threads of ~40% Alumino-silicate fire bricks vs Engineering and other bricks.

Some people in various threads have cited fire bricks having a lower thermal conductivity@ 40% alumina their thermal conductivity is ~1.13 W/mK
The modern version of the blue engineering brick has a thermal conductivty of about 1.95 W/mK
However a fairly standard red 'engineering' (actually multi-purpose) perforated brick has a thermal conductivity of 0.97 W/mK available widely @0.25p ea.
London Brick Company common brick has a thermal conductivity of 0.76 W/mK @0.37p ea
So the conductivity argument is dubious. However in the metallurgical industry we use such bricks because of other factors, e.g. resistance to attack by hot corrodents, are these a serious factor here ? Your temperatures are far lower, and we tend to use very high alumina variants
(95%) for liquid steel etc.

Thermal spalling is more or less directly related to how dense the brick is, but I guess we do not want porous surfaces in the hearth.

Any way if you insulate the hearth and the dome the thermal conductivity is not a big factor anyway, as the insulation will raise the rear temperature of any brick used here. Yes heat will pass more rapidly through the higher conductivity bricks, but in a simple sense the heat gets trapped at the back face, so the temp. difference between inside and outside these bricks is reduced. The advantage of low thermal conductivities is that back face of these bricks can potentially be at lower temperatures.

A word of caution most members of the alumino silicate class of refractory insulation materials when in blanket and board form are classed as carcinogens, check out the MSDS sheets for such materials or the HSE website. I am not qualified to rate the danger, but the risk is increased by cutting etc. and releasing fibres into the air. NB This is not due to any asbestos content, these fibres also irritate the lungs and get stuck in them.

I know that the UK vermiculite sources are checked to be asbestos free, in the US I think this was problem when in a particular mine (now closed) the mica seam ran into an asbestos contaminant load. Adverse health effects were seen in some commercial gardeners.

Again I would caution against breathing in the dust from vermiculite, so use a good quality mask if there is dust about, although the MSDS sheets I have seen for 2 major suppliers have their product rated as innocous.

But heck life is full of dangers, so don't let me put you off using such materials as a one off, the exposure limits are for people working with such materials day in day out (UK limit is about 4 x higher than that of Germany, why?).

Sorry for the length of this post, but hopefully some of the information is helpful.

[Alomran]

Re: engineering bricks vs Fire Bricks

Hi all,

I am just sizing up the pompei oven as my next project and noted the discussion in a number of threads of ~40% Alumino-silicate fire bricks vs Engineering and other bricks.

Some people in various threads have cited fire bricks having a lower thermal conductivity@ 40% alumina their thermal conductivity is ~1.13 W/mK
The modern version of the blue engineering brick has a thermal conductivty of about 1.95 W/mK
However a fairly standard red 'engineering' (actually multi-purpose) perforated brick has a thermal conductivity of 0.97 W/mK available widely @0.25p ea.
London Brick Company common brick has a thermal conductivity of 0.76 W/mK @0.37p ea
So the conductivity argument is dubious. However in the metallurgical industry we use such bricks because of other factors, e.g. resistance to attack by hot corrodents, are these a serious factor here ? Your temperatures are far lower, and we tend to use very high alumina variants
(95%) for liquid steel etc.

Thermal spalling is more or less directly related to how dense the brick is, but I guess we do not want porous surfaces in the hearth.

Any way if you insulate the hearth and the dome the thermal conductivity is not a big factor anyway, as the insulation will raise the rear temperature of any brick used here. Yes heat will pass more rapidly through the higher conductivity bricks, but in a simple sense the heat gets trapped at the back face, so the temp. difference between inside and outside these bricks is reduced. The advantage of low thermal conductivities is that back face of these bricks can potentially be at lower temperatures.

A word of caution most members of the alumino silicate class of refractory insulation materials when in blanket and board form are classed as carcinogens, check out the MSDS sheets for such materials or the HSE website. I am not qualified to rate the danger, but the risk is increased by cutting etc. and releasing fibres into the air. NB This is not due to any asbestos content, these fibres also irritate the lungs and get stuck in them.

I know that the UK vermiculite sources are checked to be asbestos free, in the US I think this was problem when in a particular mine (now closed) the mica seam ran into an asbestos contaminant load. Adverse health effects were seen in some commercial gardeners.

Again I would caution against breathing in the dust from vermiculite, so use a good quality mask if there is dust about, although the MSDS sheets I have seen for 2 major suppliers have their product rated as innocous.

But heck life is full of dangers, so don't let me put you off using such materials as a one off, the exposure limits are for people working with such materials day in day out (UK limit is about 4 x higher than that of Germany, why?).

Sorry for the length of this post, but hopefully some of the information is helpful.

Thank you for your informative opinion...this is a great forum as it has people like you.

[david s]

That's a pretty old post, over seven years ago. The new generation of CFB is now classified as exonerated as a carcinogen. It was available back then, but way too expensive. Just check the MSDS on the product as there may still be some of the older stuff around.