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Brick type decission to be made
Hi all,
I have been researching the building of a wood fired oven and when I came across this exceptional site, I have become confused with what one can only decribe as "information overload" as to which direction to go.
As it has been suggested by other members within this forums, (I have read and printed out hundreds of pages) fire bricks are the preferred matyerial from which to construct your oven but they are relatively difficult to acquire and quite expensive here in Australia. The going price is between A$4 and $5.50 each.
I have bought Russell Jeavons? book (from the UK through Amazon) only to find that his restaurant and ovens are only 25km away from me, where he uses old ?pressed reds? bricks for all of his ovens. He has built 4 in total which are used commercially, two in his restaurant. The picture of the bricks in his book show bricks that were typically made here some 50 to 100 years ago in Adelaide. To satisfy my curiosity, I am going to his restaurant in 2 weeks for a meal to check out personally his build materials and technique. I am also enrolling in 2 of his many courses that he is offering with regards to wood fired ovens and using/cooking in them.
I have also been doing some experimentation with a 1200?C fired solid clay paver 230 x 115 x 70mm @ .85c each and a fire brick 230 x115 x75mm (which is 6 times as expensive) @ $5 each.
I aquired the two sample bricks from a ?local? brick kiln that supplies many oven builders with both types of bricks. They maintain that they supply more builders of ovens with clay pavers than their firebricks.
I drilled a 55mm deep x 5mm hole into the 'mathematical centre' of the brick, put in the thermocouple probe and siliconed it in so that it was sealed from the surrounding heat and only gave the temperature increase that permiated the brick through to the centre. I then put the bricks into our new kitchen fan forced electric oven set to 180?C and read the temperature increase as the brick heated from all 6 sides. I used a Digitech QM1600 digital thermometer with 2 thermocouples. The results are as follows:
Brick #1:Red clay paver and brick #2: Cream Fire brick
Time elapsed
Brick #1 #2
5min 17?C 17?C
10 min 27? 21
15 min 40? 28?
20 min 56? 41?
25min 71? 54?
30min 86? 67?
35min 97? 79?
40min 103? 89?
45min 104? 97?
50min 104? 108?
55min 104? 114?
60min 104? 121?
I then removed the bricks from the oven, sat them on newspaper on the kitchen bench and recorded the following figures whilst they cooled.
10min 81?C 106?C
20min 75? 97?
30min 66? 85?
40min 59? 76?
50min 51? 65?
60min 49? 61?
70min 45? 56?
80min 42? 53?
90min 40? 48?
100min 37? 45?
110min 35? 41?
120min 32? 38?
These results seem contrary to what is generally believed. The red clay paver absorbed the heat quicker and gave up the heat quicker than the fire brick but ceased to heat up more than 104?C whilst the fire brick continued to increase in temperature. (This may be due to the thermocouple measuring the air in the hole rather than the internal brick surface. I should try the test again and switch the thermocouples). I am not surprised by the findings as darker objects absorb energy more readily than lighter objects, as with the paler cream fire brick.
The brick manufacturer maintains that the pavers will be quite stable and not deteriorate until the bricks reach their firing temperature of 1200? C which is highly unlikely.
With this information, which brick would be preferred for both the hearth and the dome of my oven?
Has anyone got any ideas or more importantly any similar experiences using such materials?
Neill
I have been researching the building of a wood fired oven and when I came across this exceptional site, I have become confused with what one can only decribe as "information overload" as to which direction to go.
As it has been suggested by other members within this forums, (I have read and printed out hundreds of pages) fire bricks are the preferred matyerial from which to construct your oven but they are relatively difficult to acquire and quite expensive here in Australia. The going price is between A$4 and $5.50 each.
I have bought Russell Jeavons? book (from the UK through Amazon) only to find that his restaurant and ovens are only 25km away from me, where he uses old ?pressed reds? bricks for all of his ovens. He has built 4 in total which are used commercially, two in his restaurant. The picture of the bricks in his book show bricks that were typically made here some 50 to 100 years ago in Adelaide. To satisfy my curiosity, I am going to his restaurant in 2 weeks for a meal to check out personally his build materials and technique. I am also enrolling in 2 of his many courses that he is offering with regards to wood fired ovens and using/cooking in them.
I have also been doing some experimentation with a 1200?C fired solid clay paver 230 x 115 x 70mm @ .85c each and a fire brick 230 x115 x75mm (which is 6 times as expensive) @ $5 each.
I aquired the two sample bricks from a ?local? brick kiln that supplies many oven builders with both types of bricks. They maintain that they supply more builders of ovens with clay pavers than their firebricks.
I drilled a 55mm deep x 5mm hole into the 'mathematical centre' of the brick, put in the thermocouple probe and siliconed it in so that it was sealed from the surrounding heat and only gave the temperature increase that permiated the brick through to the centre. I then put the bricks into our new kitchen fan forced electric oven set to 180?C and read the temperature increase as the brick heated from all 6 sides. I used a Digitech QM1600 digital thermometer with 2 thermocouples. The results are as follows:
Brick #1:Red clay paver and brick #2: Cream Fire brick
Time elapsed
Brick #1 #2
5min 17?C 17?C
10 min 27? 21
15 min 40? 28?
20 min 56? 41?
25min 71? 54?
30min 86? 67?
35min 97? 79?
40min 103? 89?
45min 104? 97?
50min 104? 108?
55min 104? 114?
60min 104? 121?
I then removed the bricks from the oven, sat them on newspaper on the kitchen bench and recorded the following figures whilst they cooled.
10min 81?C 106?C
20min 75? 97?
30min 66? 85?
40min 59? 76?
50min 51? 65?
60min 49? 61?
70min 45? 56?
80min 42? 53?
90min 40? 48?
100min 37? 45?
110min 35? 41?
120min 32? 38?
These results seem contrary to what is generally believed. The red clay paver absorbed the heat quicker and gave up the heat quicker than the fire brick but ceased to heat up more than 104?C whilst the fire brick continued to increase in temperature. (This may be due to the thermocouple measuring the air in the hole rather than the internal brick surface. I should try the test again and switch the thermocouples). I am not surprised by the findings as darker objects absorb energy more readily than lighter objects, as with the paler cream fire brick.
The brick manufacturer maintains that the pavers will be quite stable and not deteriorate until the bricks reach their firing temperature of 1200? C which is highly unlikely.
With this information, which brick would be preferred for both the hearth and the dome of my oven?
Has anyone got any ideas or more importantly any similar experiences using such materials?
Neill
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