"The first stage [for Mark Dymiotis] was to build a traditional oven [in his back yard]. The local council were unsure whether to classify it as a barbecue or an incinerator!"
("Mark's Bread" in "Stephanie's Australia", by Stephanie Alexander")
Materials:
25 standard house bricks (nix)
trailerful of clayey dirt (free)
straw (1 bale $6.50)
15 firebricks 23x11.5x2.5cm @ $5.00 ea.
1 1/2 bags Densecrete (@ $85 per 25kg. bag.)
1 tub-shaped basket 61x58cm ($23.50)
newspaper
masking tape
aluminium flashing ($10)
wood for door
short length flue (nix)
cardboard
tray
trowels, $6.95 for two
25 standard house bricks (nix)
trailerful of clayey dirt (free)
straw (1 bale $6.50)
15 firebricks 23x11.5x2.5cm @ $5.00 ea.
1 1/2 bags Densecrete (@ $85 per 25kg. bag.)
1 tub-shaped basket 61x58cm ($23.50)
newspaper
masking tape
aluminium flashing ($10)
wood for door
short length flue (nix)
cardboard
tray
trowels, $6.95 for two
1. Prepare base, making sure it is level.
2. Position bricks, 5x5 rows, about 2.5cm apart. Shovel over adobe dirt, and sweep into gaps. Water in dirt. Repeat this process four times altogether.
3. Mix up Densecrete. Spread on bricks to width of basket, 1cm thick. Set in firebricks, 3x5 rows.
4. Mix adobe. Proportions are according to the quality of the dirt (which should be dirt, not potting soil nor anything like unto it). Less cohesive dirt will need more straw; more cohesive dirt will need less straw. Ideally, the dirt should have a significant amount of clay. Spread alternating layers of dirt and straw in wheelbarrow or tub. Add enough water to moisten, and mix. The mixture should be firm enough to form a ball when cupped within your hands.
5. Saw basket in half. If it spreads, bring it back to shape with two pieces of wire or string fastened on the cut edges, stretching from side to opposite side. Position basket half over firebricks. Cover basket with newspaper, fastening it on with masking tape.
6. Make the entrance. You can do this either of two ways:
a) Cut aluminium flashing to fit front of oven exactly. Cut out a square () in the middle to fit in the door. Attach to basket with masking tape.
b) Place square tray where you would like door. Fill gaps between tray and basket with cardboard, fastening it on with masking tape. (The tray will be removed as soon as adobe is set though not rock-hard.)
7. Cut piece of flue, about 20cm long. Make one side flat, and one side angled. Fasten flue, angled-side down, to basket with masking tape.
8. Spread basket with Densecrete 2cm thick, going down the front flashing or cardboard. You can either:
a) Wait until Densecrete hardens before applying adobe.
b) Work simultanenously. Apply a patch of Densecrete, and immediately cover it with adobe.
9. Cover entire structure, including housebricks, with adobe, working to the edge of the flue and door. Adobe needs to be 10-12.5cm thick. Make sure the top is not too rounded, or it will not hold heat as efficiently.
10. Allow oven to dry for at least a week. During this time, place a tarp over (not on) it at night, or during rain. Cracks will develop as it dries and settles.
11. Make door to fit entrance, either:
a) Out of wood to fit entrance made of flashing (wooden doors need to be soaked in water before using). Attach a wooden handle.
b) Out of adobe or densecrete, using the tray as a mould. When making a door this way, the handle needs to be set into the adobe or densecrete. We used two trowels, covering the spreading part and leaving the handles exposed.
12. When oven is hard and dry to the touch, light the first fire. This is a fast a furious fire made up of kindling and small wood. The flames need to leap up high enough to ignite the basket. Position a fire screen over the entrance. Oven may sweat out the remaining internal moisture (although ours didn't), and will progress from warm to hot to the touch. After oven has cooled, make a light slurry out of the adobe dirt and water, and seal up cracks. Allow to dry once more. Oven is now ready to be used.
As time progresses, and with use, more cracks will develop. These are normal, and running repairs are a part of owning the oven. simply keep some adobe dirt on hand, and mix up a slurry to patch them up whenever they appear.
3. Mix up Densecrete. Spread on bricks to width of basket, 1cm thick. Set in firebricks, 3x5 rows.
4. Mix adobe. Proportions are according to the quality of the dirt (which should be dirt, not potting soil nor anything like unto it). Less cohesive dirt will need more straw; more cohesive dirt will need less straw. Ideally, the dirt should have a significant amount of clay. Spread alternating layers of dirt and straw in wheelbarrow or tub. Add enough water to moisten, and mix. The mixture should be firm enough to form a ball when cupped within your hands.
5. Saw basket in half. If it spreads, bring it back to shape with two pieces of wire or string fastened on the cut edges, stretching from side to opposite side. Position basket half over firebricks. Cover basket with newspaper, fastening it on with masking tape.
6. Make the entrance. You can do this either of two ways:
a) Cut aluminium flashing to fit front of oven exactly. Cut out a square () in the middle to fit in the door. Attach to basket with masking tape.
b) Place square tray where you would like door. Fill gaps between tray and basket with cardboard, fastening it on with masking tape. (The tray will be removed as soon as adobe is set though not rock-hard.)
7. Cut piece of flue, about 20cm long. Make one side flat, and one side angled. Fasten flue, angled-side down, to basket with masking tape.
8. Spread basket with Densecrete 2cm thick, going down the front flashing or cardboard. You can either:
a) Wait until Densecrete hardens before applying adobe.
b) Work simultanenously. Apply a patch of Densecrete, and immediately cover it with adobe.
9. Cover entire structure, including housebricks, with adobe, working to the edge of the flue and door. Adobe needs to be 10-12.5cm thick. Make sure the top is not too rounded, or it will not hold heat as efficiently.
10. Allow oven to dry for at least a week. During this time, place a tarp over (not on) it at night, or during rain. Cracks will develop as it dries and settles.
11. Make door to fit entrance, either:
a) Out of wood to fit entrance made of flashing (wooden doors need to be soaked in water before using). Attach a wooden handle.
b) Out of adobe or densecrete, using the tray as a mould. When making a door this way, the handle needs to be set into the adobe or densecrete. We used two trowels, covering the spreading part and leaving the handles exposed.
12. When oven is hard and dry to the touch, light the first fire. This is a fast a furious fire made up of kindling and small wood. The flames need to leap up high enough to ignite the basket. Position a fire screen over the entrance. Oven may sweat out the remaining internal moisture (although ours didn't), and will progress from warm to hot to the touch. After oven has cooled, make a light slurry out of the adobe dirt and water, and seal up cracks. Allow to dry once more. Oven is now ready to be used.
As time progresses, and with use, more cracks will develop. These are normal, and running repairs are a part of owning the oven. simply keep some adobe dirt on hand, and mix up a slurry to patch them up whenever they appear.
'Bakery, with mills for grinding grain, and an oven.' Pompeii.
