Building a wood fired bread oven - Completing the main dome

This evening the main dome of our wood fired bread oven was completed.  We have been racing against the cold weather that has been forecast and unfortunately it has come a day early.  It looks like we could have temperatures below -5°C for the next month or longer.  In these temperatures the water content of the mortar will freeze which would not be good for the brickwork. In order to be able to continue in these temperatures, the dome needs to be finished and am electric heater sealed inside, this will keep the brickwork above freezing, and hopefully warm enough for the mortar to harden. 

I have been working flat out in the evenings in attempt to finish the main dome.

Main dome completed

You can see here the completed main dome.  The larger gaps in brickwork have been filled with a mix based on the the refractory mortar with a courser aggregate added.  This makes it more suitable for filling larger gaps and will help it dry out.  

I would have liked to leave the form-work for a couple of days, but a heater is needed under the arch, so the supports had to come out.  Fortunately the form-work came out without bringing all the brickwork down leaving the first glimpse of what the inside of the oven will look like.

Inside the oven arch

A little more brickwork still needs finishing before the oven can be wrapped up in insulation, so I am still working flat out.  I will update with further progress once I can take some more pictures.

Building a wood fired oven - dome bricks started

The first few dome bricks for our wood fired bread and pizza oven have now been set.  It is more usual for this to be done using a form for a single brick width so that.  The single brick width dome technique as described by Alan Scott in the book the Bread Builders, which I discussed in a blog post here, involves moving the form work after each brick arch has been set.  I have decided to make a full length form-work so that each course of dome bricks can be offset by half a brick for improved strength and resistance to cracking, it also allows me to build the entire dome before removing the support without worrying about it collapsing.  As I am racing the cold weather that is coming in a couple of days, and due to the lot temperatures here, the mortar is going off very slowly, so I need the dome finished fast and supported until it is fully finished.  

Form-work positioned in the oven

The form-work is adjusted to the correct height using four stacks of bricks and two quick substantial pieces of wood, cut the the correct length of the form.  The form has been trimmed to be just small enough to be removed through the oven mouth.

Angled dome support bricks

The bricks at the top of the side wall have been angled to maximise contact with the first dome brick.

First 4 rows of dome bricks

When laying the first 4 rows of dome bricks, some of the bricks did not want to stay in the correct position, so small pieces of fire brick have been wedged in the tapered gap between dome bricks.  Only a small amount of refractory mortar has been used here,  where the tapered gap become wider than about 6 mm, it has been left unfilled.  This will later be backfilled with a different mix of mortar.

Dome bricks supported by form-work

Care has to be taken in order to make the corners of dome bricks meet as closely as possible.  The bricks should fit together with almost no mortar separating them.  This is not possible in reality  due to slight inconsistencies in brick shapes and sizes.  

The weather here is looking like getting very cold in a couple of days time, so I need to get this dome finished, the supports removed and a heater under the dome before I get problems of the mortar freezing and destroying all our hard work.

Building a wood fired oven - dome form

Today I was doing the preparation work that is needed before I can start to lay the bricks of the dome of the wood fired bread oven.  I have already cut and set the angles bricks that will brace the ends of the dome.  These bricks were cut using a large angle grinder with a diamond abrasive disk.  These bricks transfer the load of the dome to the steel strapping on the outside of the oven.

Dome support bricks ready for pointing and cleaning

In order to create the dome I need a parabola shaped form that will support the bricks until the mortar goes off.  The shape was drawn on a piece of paper to use as a template and then transferred onto a sheet of plywood.  I then cut out the shape a little oversized on the band-saw and then finish on the sander.  Once I am happy with the shape it is used as a template to 3 more sheets of ply, this time screwed together so I can make 3 with one pass.

Cutting out the form supports

 The 4 supports are then screwed to a sheet of plywood on their flat edge.  For the curved surface, as it will need to be quite strong, another sheet of 12mm ply will be bent over the supports.  In-order to make the ply flexible enough, cuts are made 2/3 of the way through the plywood using a circular saw.  I have made these cuts every 2 cm.  If you require a tighter curvature then the cuts will have to be closer together.

Making ply flexible for the form-work

The flexible sheet of ply-wood is then bent and screwed to the supports.  This is best done working from the centre out.  To ensure a strong form, a bead of polyurethane  wood glue is first applied to the supports. Screws will need to be more frequent the tighter the curvature required.

Finished dome form

With the form-work finished I am ready to the start the exciting bit, laying the dome bricks.

Stewed lamb shanks with potato gnocchi

Early afternoon, while planning what to eat for dinner last night, I had a quick look in the freezer and spotted two lamb shanks I have from the lambs that we raised this year.  How these were butchered I covered in an article here, It's time for the lambs.  Lamb shanks are not expensive and due the work the lower leg muscles do and the amount of connective tissue, when cooked right they make the most amazing stew with masses of flavour with super soft gelatinous meat.

This dish could be cooked in the oven in a heavy gauge pan, but this time I am doing this on the hob in a deep pan.

The trick to making this a really special dish is what you put in the sauce.  The flavour is going to come from the selection of vegetables. This time I finely chop onion and soften in some olive oil then add the lamb to the pot.  Next, a few handfuls of diced vegetables are added. This time I have used carrots, celeriac and parsnips. A few porcini mushrooms, a bunch of dried thyme and a tablespoon of balsamic vinegar. Then enough water just to cover the meat is also added.  Season with salt and pepper.

The stew is then put on a very low simmer.  I like to use a sheet of foil over the pan with the lid on top in order to make a very tight seal. The slower this is cooked the softer the meat will be. I then leave this simmering all afternoon until about an hour before we want to eat. The sauce is then separated from the meat and vegetables in order to thicken the sauce by boiling off much of the water.  I do not do this with the meat in as it does not require further cooking.  During the reduction process I add a little extra lamb stock to make the sauce even richer.  While the sauce is slowly reducing I prepare some potato gnocci.

Potato Gnocchi

Bake in the oven, in their skins, enough potato for the number of people you are feeding.  For two people I bake about 500g of potatoes. As the potato is being roasted the quantity shrinks due to moisture loss, but this is desirable as the lower moisture content of the cooked potato is going to make much better, more intensely flavoured gnocchi.  Once soft, remove the skins and press the potatoes through a potato ricer. Dust the riced potato in a little flour and season with salt and pepper.  As the potato has been riced the flour and seasoning can me mixed through without working the potato. I would always use a ricer for this, other methods of mashing the potato will overwork it and the gnocchi will be rubbery.  Once mixed, transfer the potato to a lightly floured surface gently press into a ball  and then roll out into a sausage shape about 2 cm diameter.  I then cut into disks and press a small indentation into once side with a finger.

The gnocchi are gently transferred into boiling water, once they start to float I give them another 30 seconds and they are done.  I strain the gnocchi and allow to stand for a couple of minutes while I melt some butter in a frying pan, then toss the gnocchi in the butter until they colour a little.

I then served the lamb on top of all the stewed veg with the gnocchi on the side and the thickened gravy poured over the top. This is a super meal that costs very little and is really simple to prepare without taking much of your time.  Its just a real shame that a lamb only has four shanks.

New Experiment - Brioche Dough

Brioche dough is something that I have never tried baking, and I don't think I have ever eaten a proper bit of brioche.  As I did with my focaccia experiment, I will not be following a recipe from anyone else.  I like to follow a process with all my recipes and this brioche post is an outline of the process I follow.

Brioche bun with wild plum jam

First I have done a little reading about brioche, I found some interesting recipes, this one from Michel Roux is interesting and wikipedia's entry has a lot of historical context.  There seems to be a range of dough that could be considered brioche, most are bread dough fortified with eggs and butter. They range from the lightly fortified, but still more fortified than my sweet bun dough, with only a small amount of egg and butter, to heavily fortified. The Roux recipe is right at the rich end of the scale. 6 eggs and 350g of butter for 500g of flour is a lot of enrichment.  I don't really know how much fat you can put in a dough before the yeast retards so much that it will no longer ferment, but this is about as rich a dough as I have come across.

For my dough I want to put enough enrichment into it to produce a rich brioche, but I would also like to have a longer slower fermentation do develop some extra flavour.  In order to do this I will be using slightly less butter and I will be pre-fermenting a third of the flour with about 5g of instant yeast. Pre-fermenting will allow the yeast to multiply and by-products of fermentation to be produced rapidly without the presence of fat.

The pre-ferment is then thinned by adding 50ml of cold milk, the remainder of the flour added along with the eggs, well beaten first.  The dough is roughly mixed and then left to stand for 15 minutes, this will reduce the amount of kneading required.  I would make my dough as wet as possible in order to get the lightness and extended texture inside that I want.  This poses one of the problems I will face today as a really wet dough is quite easy to make with a mixer, but I do not have one, so this will need to be mixed enough to develop the gluten by hand.

After standing, 200g of softened butter is mixed into the dough, mixing for another 10 minutes brings the dough to a consistency that I am almost happy with, by this time, my arms are burning and ready to give up on the mixing.  Further development of the gluten is achieved by gently stretching and folding the dough a few times every 30 min during fermentation.  Fermentation is given 3 hours at about 20°C and then the dough is retarded in the refrigerator for 5 hours.  After laying a few bricks for my new wood fired oven the dough is taken out of the refrigerator and warmed up again for 30 mins before shaping.  I do not have any proper brioche bun tins or loaf tin, so instead I use large muffin cups and a regular loaf tin.  Each tin gets 3/4 of a portion of dough shaped into a ball in the bottom and then on top a smaller ball with the remainder of the portion.

Finally, I prove the dough for about 2 hours at room temperature until it is a little over 2x bigger than the shaped dough. Then baked at about 190 °C for 15 minutes for the buns, and about 35 mins for the loaf.

I am very happy with my first attempt.  They are light and fluffy with bags of lovely flavour, I suspect a lot of this is from the really good quality butter and the excellent eggs.  We have now tested the result served with some of my Wife's wild plum jam.

For the bakers reading, here is the crumb shot!

Building a wood fired bread and pizza oven - Soldier bricks

The oven has kept me really busy this weekend, yesterday, fabricating the steel strapping and today laying the soldier bricks.  These are the last bricks to be laid before I can start the brick dome and they need to go off well so I really wanted to get this done before I head the Netherlands this week for work.  This will give the mortar a week to harden before I start on the dome.

The picture below shows the completed soldier bricks, as all the bricks are slightly different sizes I have had to choose which side of the brickwork I want to look good and as the outside is hidden by insulation, only the inside is visible, so the bricks has been aligned on the inside surface.

Completed soldier bricks

As these bricks will be pushed outward by the weight of the dome, they need to be braced by the mettle strapping.  The small gap (0-4 mm depending on the size of the brick) between brick and steel is filled with refractory mortar.

Starting to be able to see what the oven is going to look like, when finished.  Today was the first day that I looked at the oven and could imagine rows of bread baking in there.

It was much easier to work today as I finally installed some overhead lighting in the bakery.  This shot shows the transition between oven and chimney.  

From this angle I can really imagine the fire burning or the bread baking, maybe a pizza or two during the later stages of firing.  Just behind the door opening you can see the arch support bricks for the lower reducer arch.  Just realised I am going to have to write a blog post explaining my design and why I chose this over many other more popular and tested designs. That will be for another day.

Building a wood fired bread and Pizza Oven - Fabricating the arch supports

It's been a few days since I had chance to work on the wood fired oven project.  The temperatures are forecast to be above zero for a few days, so I had to make progress today.  Even though this is Poland in January, I was able to work all day in just a shirt.  The goal for the day was to fabricate the steel strapping that is designed to prevent the weight of the arch from pushing the supporting brickwork outwards.

Before staring on the steel work, I decided to mock up the soldier bricks that will support the roof dome.  I also rendered the cast lintel with refractory mortar to give the surface a harder wearing outer layer and to fill any voids.  This was a great suggestion made by Terry on The UKWoodFiredOvenForum.  If anyone is planning on building their own oven, would recommend signing up to this forum and discuss you plans with the other members.

Soldier bricks mocked up

For my steel arch strapping, I have chosen to use this 'C' section, I was not entirely sure what size to use, without going into engineering calculations, so instead I used the largest size I could get.  My oven design has a low, parabolic arch which will produce a substantial outward force on the soldier bricks, so it is very important that my strapping is ridged enough.

steel section chosen for bracing arch supports

 The steel frame is first cut to size using a cutting disk on a hand held grinder, then the vertical angle pieces and flat section, lower perimeter pieces and carefully positioned to be in the correct alignment before two small tack welds done on each joint.  The tack welds are small enough to make the frame ridged enough, without pulling the frame out of shape as the weld cools.  My welding skills at beginner level, but I really enjoy doing this bit.

Lower perimeter and vertices tack welded 

 In order to reach the framer on the wall side of the oven, I had to remove the plastic sheet siding.  Once the oven is finished we will build some proper walls.

Welding the oven strapping

 In order to weld the larger arch support pieces in place, which weigh about 60 Kg each, a support block at each end at the correct height made this part of the job very easy.  In this picture you can clearly see the two little tack welds.

Temporary support block while tack welding

 The same technique was used to position the tension strap above the oven door and at the rear of the oven.

Above door tension strap

 Once all the tack welds are in place the frame is already very ridged and has no noticeable flex.

Tack welds completed

 Finally each joint is re-welded with a proper full length weld making sure that the weld penetrates fully to give maximum strength.  With the oven strapping now completed, the next step will be to set the soldier bricks.

Oven strapping now completed