Welcome to my "Outdoor oven workshop" blog-site. This is a brief run through of a two day workshop that I attended in The Lough, Cork city. The course was set up and lead by Hendrik Lepel who has completed more than his fair share of Pizza ovens. For further details on his workshops contacted him on 086 883 8400 or email – kirdnehl@hotmail.com.
Saturday, April 16, 2011
Stage 1 - Hearth template
To start off you will need a strudy base to work off. As this workshop was only on for two days, Henrick had the base constructed before we arrived.
The base consisted of block work as shown in the photo below this post. Paving slabs were used on top of the walls to support the finished oven. The wall was clad after the workshop with a stone finish and a treated timber counter top was placed over the slabs by the door to the oven. Steel or bricks could also be used to form a counter top.
This is the before picture:
Close up of brick arch /doorway:
Brick template for hearth:
The base consisted of block work as shown in the photo below this post. Paving slabs were used on top of the walls to support the finished oven. The wall was clad after the workshop with a stone finish and a treated timber counter top was placed over the slabs by the door to the oven. Steel or bricks could also be used to form a counter top.
This is the before picture: Close up of brick arch /doorway: Brick template for hearth:
Day one
On day one of the workshop we,
- Made a brick template for the hearth,
- layed the hearth of the oven,
- created the temporary sand mould for the oven void,
- constructed the first/inner layer of the oven with "oven mud" (mixed on site)
As you will see from the photos we made two different ovens because there was ten people in the workshop. The main one is the oven with the brick arch and the second one was a temporary oven set up with no arch. The ovens can be done with or without a brick arch. I will be switching between the ovens with the photos. The process of building is the same.
Stage 2 - Sand blinding for hearth
The sand blinding will rest on top of the paving slabs. A smooth and level surface will save you time when laying the bricks.
Sand blinding: A level base of sand will form the level floor for the oven. Roughly 25mm /1 inch of sand should suffice. Make sure the sand has a smooth finish because your bricks will not rest properly.
Sand blinding: A level base of sand will form the level floor for the oven. Roughly 25mm /1 inch of sand should suffice. Make sure the sand has a smooth finish because your bricks will not rest properly.
Checking levels: After the sand has has been smoothened out you will have to check that it is almost level. The smallest of a fall towards the door ope is needed to prevent water from lodging in the oven.Stage 3 - Laying bricks
The bricks that you require for the hearth will have to be fire bricks as they store the heat for the cooking process. You can buy them in building supply shops. If you want a cheaper option, you could take the bricks from an old storage heater. Note: Soak bricks before placing if you are going to use mud morter (same mud mix to create the inner layer of oven), on the oven floor instead of sand blinding. This will prevent the bricks from soaking the moisture from the mud and weaken the mix.
Lay the bricks starting from the door ope. Work your way to the back as you will see in the following pics. Follow the brick patterns shown.
Ensure that the joints between the bricks are butted against each other. We used the kiss and slide method between the side of the new brick against the previously placed one.
Check the level before and after tapping down the bricks. Make sure that all bricks are firmly tapped down with a rubber mallet. Use a piece of timber if you only have a normal hammer. This will protect the bricks.
Lay the bricks starting from the door ope. Work your way to the back as you will see in the following pics. Follow the brick patterns shown.
Ensure that the joints between the bricks are butted against each other. We used the kiss and slide method between the side of the new brick against the previously placed one.
Check the level before and after tapping down the bricks. Make sure that all bricks are firmly tapped down with a rubber mallet. Use a piece of timber if you only have a normal hammer. This will protect the bricks.Stage 4 - Sand mold
After you have worked out the measurements for the oven. You need to form a sand mold for the oven void. On the workshop we made an oven that was 22.5" in diameter and the height to underside of roof was 16". We set out the full circle with a marker attached to a string and a nail as the center point. The height was set up with a stick cut to the appropriate height.
The sand mold has to stay inside the circle. work the sand into a half sphere, using the stick as a guide for the height. Don't add too much sand at once as it will be difficult to manage. Do not rush this part.
Make sure that you make the sand smooth as this will allow for a smooth finish on the inside of the oven when you remove the sand (in stage 6).
Use a piece of timber and wedges to hold the sand in at the door ope.
The sand mold should look like this after it is finished
Use wet newspaper to prevent the sand sticking to the oven mud in the next stage.
The sand mold fully covered with wet newspapers ready for the next stage.
The sand mold has to stay inside the circle. work the sand into a half sphere, using the stick as a guide for the height. Don't add too much sand at once as it will be difficult to manage. Do not rush this part.
Make sure that you make the sand smooth as this will allow for a smooth finish on the inside of the oven when you remove the sand (in stage 6).
Use a piece of timber and wedges to hold the sand in at the door ope.
The sand mold should look like this after it is finished
Use wet newspaper to prevent the sand sticking to the oven mud in the next stage.The sand mold fully covered with wet newspapers ready for the next stage.Stage 5 - First layer (Dense "oven mud")
This is the technical part of the oven. The mix that we used for the main oven was one part soil with added clay, two parts course concrete or sharp sand and water. The temporary oven had one part of earth dug from garden instead of the soil with clay.
The colour of the mix for the temporary oven was a bit lighter as shown. this was our sample, your sample does not have to look like this. This is the tricky part. You have to pack the oven mud densely for this to work. A 4" thick layer is what you need for a pizza oven. Make the layer thicker if you want to cook or bake. Use one hand to keep the edges strong and squash down with the back end of your finger. Do not pat ot slap the mix, as that brings the moisture to the outside and makes it go soft. Metal trowels will also bring the moisture to the outside.Use timber at the sides to press the mix into its self.
If you are using the soil dug from a garden. Make sure that you dig below the topsoil which has organic matter in it. Use the sub soil which has clay mixed in naturally.
To check your mix you will need to ball up some in your hands for the drop test. Shoulder height is recommended for a drop distance.
- If your ball shatters, you will need to add either water, clay or both,
- If your ball flattens out, it is too wet,
- Your ball needs to stay intact within reason of course, it can be a deformed sphere with cracked edges.
Elbow grease is what you need to mix the materials together for the first layer. Another method we used was to step and squish it together by sliding to the side. Twist and slide as Henrick would say. More feet make it faster. The mix seen in this photo was used for the main oven.
The colour of the mix for the temporary oven was a bit lighter as shown. this was our sample, your sample does not have to look like this. This is the tricky part. You have to pack the oven mud densely for this to work. A 4" thick layer is what you need for a pizza oven. Make the layer thicker if you want to cook or bake. Use one hand to keep the edges strong and squash down with the back end of your finger. Do not pat ot slap the mix, as that brings the moisture to the outside and makes it go soft. Metal trowels will also bring the moisture to the outside.Use timber at the sides to press the mix into its self. The most important part about this stage of the build is to keep the thickness the same throughout. Make sure as you go higher up the sand mold that the face of the layer angles upwards. Use a bit of timber as a guide pressed lightly against the sand mold at an angle following the curve.
I have an example in a later photo to show what happens when the layer has a different thickness.
This is what it should look like when finished. It resembles an igloo.
Stage 6 - Removing sand mold and first fire
Depending on how wet or dry your mix was, you could scrape out the sand form. Only do this if you are sure that the first layer is dry enough.
Be care full when scraping out the sand as the oven mud is fragile at this stage. Do not use tool for this stage. Use your hands as they can feel for the newspaper. Make sure that all of the sand is gone and don't worry about the paper as the fire will get rid of that.
This is what the temporary oven looked like after we scraped it out. There was no brick arch for this so we cut out a hole angled outwards. The inner part of the angle that is inside the oven should be the desired door ope height. Work your way out from there.
This is the main oven. Sand came out no problem. Also please notice that the floor is flat, as it should be.
And we have fire!! Roll up newspaper it knots and add a few twigs. Do not make this fire too hot as it could crack the roof of the oven and collapse.
Be care full when scraping out the sand as the oven mud is fragile at this stage. Do not use tool for this stage. Use your hands as they can feel for the newspaper. Make sure that all of the sand is gone and don't worry about the paper as the fire will get rid of that.This is what the temporary oven looked like after we scraped it out. There was no brick arch for this so we cut out a hole angled outwards. The inner part of the angle that is inside the oven should be the desired door ope height. Work your way out from there.This is the main oven. Sand came out no problem. Also please notice that the floor is flat, as it should be. And we have fire!! Roll up newspaper it knots and add a few twigs. Do not make this fire too hot as it could crack the roof of the oven and collapse.Leave to dry over night or any day after that. But not too long as the elements will break down the oven mud faster
Day Two
On day two of the workshop we,
- put on insulation layer,
- put on plaster layer,
- lit another fire to test it out.
This day was messy. Use gloves and old shoes for the mixing. We used horse manure, clay and extra straw for the insulation layer.
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