Rustic Sour Dough Loaf

Now the oven has been insulated it is time to try my regular bake in a wood fired oven.  This is the first time I have done my regular weekly bake in a wood fired oven and over the next few weeks I will be refining my technique until I get the results that I want every time.

This week I chose to bake just 9 loaves as I don't yet know how the oven will perform.  As it turns out, the oven holds heat very well and looking at the cooling rate, it looks like we will be able to bake at least 5 full loads per firing.  

not quite a full load

The oven holds steam extremely well which results in a superb oven spring.  I have been experimenting and improving my technique for  a few years, but in a regular oven have never managed to achieve close to these results.

Shame you can't hear the crust crackling as they cool

With the long slow fermentation and natural leaven, this bread take 3 days to make, but the result is incomparable to a commercial baked bread in both flavour and texture.

Good structure to the crumb

There is still some work to do on the oven before we can start to bake seriously, but I think we are not far away now.

Building a wood fired bread and and pizza oven - Insulation and more Insulation

Tomorrow I am planning to bake my third load of bread in the wood fired oven, but this time it is going to be properly insulated.  First I have wrapped the oven in thick aluminium foil, followed by a layer of ceramic blanket and another few layers of aluminium foil.  

Oven wrapped in Aluminium foil and ceramic blanket layers

 The 1.2 cubic meters of Perlite have been pored over the top to fill the void between the inner brickwork of the oven and the exterior cladding.  This gives an average thickness of insulation of about 20 cm.

 Now the insulation is in I have lit a full burn with the oven almost full of wood, pre cut to the correct length.  The fire was lit at the front of the oven and it naturally burns to the back.  The first third of the burn is not very efficient as there is too much fuel/gases being burned as it goes up the chimney, but by the time the fire has reach a third of the way back the wood has been heated so much that it has turned to charcoal.  The remaining fire is super hot, controlled to a nice burn rate.

  Tonight, once the oven has calmed down a bit we will be having pizza.  The oven will then be sealed and left to equilibrate over night, ready for baking sourdough tomorrow.

Building a wood fired bread and pizza oven - A box to hold insulation

It will probably never be said that my choice of exterior cladding for this wood fired oven is anything to look at, but on the other hand in terms of function it is just a box to hold all the insulation in.  In this case that is going to be a very large amount of insulation.  It is thinnest at the front around the door at a thickness of about 11cm.  Around the remainder of the oven there is a gap between oven mass and insulation of approximately 20 cm.  Under the hearth there is 10 cm of Foamglass.

Exterior of the oven

 The outside of the oven has been tack welded together, in each corner there is steel angle which allows some overlap and allows some adjustment of the panels.  The corners were clamped together and checked with a spirit level.  The box is held up by first attaching some lengths of steel to the concrete slab with rawl plugs and  hex head screws.  The panels are then also welded to those lengths of steel.

Foil faced ceramic and mineral wool insulation can be seen

 The front of the oven and the exterior cladding is separated with layers of foil faced insulation, ceramic on the hottest side and then mineral wool.  This needs to be kept separate from my baking so this will be encapsulated with sheet aluminium 0.2 mm thick.  This is  enough to hold its shape, but not so thick that it will conduct lots of thermal energy away from the hot side of the wall envelope.

Aluminium sheet to encapsulate insulation around the door

Tomorrow I am hoping to finish insulating the oven and fire the oven ready to bake on Sunday and Monday.

Building a wood fired bread and pizza oven - Fabricating an oven door

So for my wood fired oven I am going to make the exterior case out of 3mm thick sheet steel.  This evening I wanted to get the front panel that includes the oven door made.  The corners of the exterior of the oven will be made of steel angle section which will give me some room to adjust the position of the panels before welding.  This should enable me to get the position of the door hole closely aligned with the opening of the oven.  To enable fast loading and unloading of the oven, I have opted for a door that is hinged at the top and swings up and our of the way.  I will need to come up with some kind of counter balance to both keep the door shut and open.

I have  got as far as tack welding the door to the front of the oven.  I still have to make the door opener and complete these welds, but for now the tack weld will do as they will be easy to grind off if I need to move something.  I will also spend a bit of time cleaning up with a grinder to make thing look nice.

Currently the door is insulated with high temperature foil faced rock-wool sandwiched between the oven face plate and a stand off plate.  The finished oven door will have the rock-wool and stand off plate sealed by a thin sheet of aluminium to prevent any insulation falling out into the oven.

Hopefully tomorrow the panels will be attached to the oven ready for the loose fill perlite insulation.

Wood fired bread and pizza oven - The bakers has a roof

Finally the bakery has a roof and this is the first bit of work we have got someone in to do.  I can now keep the oven dry and finish the wood fired oven without getting dripped on through holes in a tarpaulin.

my two girls with the roofers working on the bakery

the finished roof

Once the oven is finished we will clad the outside of the bakery to match the house.

Building a wood fired bread oven - Rear wall - arch junction

Its been a couple of weeks since I had the opportunity to do any further work on the wood fired oven.  After rushing to get the oven ready for our daughters birthday, it's now time to correct the bits that I did not have the material to do correctly the first time.  It is desirable that the oven is as air tight and possible when the doors and damper is shut, but the junction between the rear wall and arch is a problem, the arch expands much more than the wall and it is therefore not possible to tie the two together rigidly.  This is all a bit of an experiment, but the approach I have chosen to try, is to leave an expansion gap of about 6 mm which is the blocked with a refractory gasket material.

To create the expansion gap, 3 courses of bricks have been removed from the rear wall.  This was a good opportunity to take a picture of the back of the reducer arch.

I don't think this gasket materiel will completely seal the oven, but the gap should help maintain the integrity of the brickwork and the gasket will keep some of the smoke / gasses and steam from escaping.

Now this is complete, the mortar will have to be left to dry for a few days and then curing fires will be started again to drive out any remaining moisture before the oven can be used again for baking.  This should give me time to build to exterior cover that will hold all the insulation.

Building a wood fired bread and pizza oven - first bread bake

Today we baked bread for the first time in our almost finished wood fired oven and as I have never baked more than about 2.5 KG of dough at one time before I thought it was about time I had a go at doing a larger batch.  The dough I was using today is my standard bake that I have been doing most weeks for the last couple of years.  It is almost the same every time but I do tend to vary the hydration.  This time I went to the wet end of the scale, which for this flour, which is not bread flour (as it is not readily available here) is about the following proportions;

Starter

• 2 Kg plain type 650 flour
• 2 litres of water

Final dough

• 8 Kg plain flour type 650
• 1.5% salt
• 6 litres of water

The starter expanded from about 100 g to 500 g on Wednesday night and then again to 2 KG on Thursday morning. The final dough was mixed together Friday evening, rested for 30 mins and then kneaded by hand for about 20 mins. Fermentation was done for 5 hours at 15 °C and then retarded overnight at 6 °C.  The dough was degassed and stretched a few times during the initial fermentation.

I lit the fire before breakfast and did about 1 and a half burns over the space of about 3 hours, the slow burning embers were then spread out and took about another hour to lose most of their colour.  About the time of raking out the fire I divided the dough, a little shaping and then placed in plastic boles that had been greased with olive oil.  After 2 hours the embers were raked out of the oven and the hearth mopped with a wet rag wrapped around the rake.  This is a part I really need to refine as I currently do not really have a good way of cleaning the hearth after firing.

Towards the end of firing. 

 After about 2.5 hours of proving the hearth temperature was around 300 °C and the vault about 360°C so I decided to do a test bake with a single loaf.  This turned out rather well and after 30 minutes the internal temperature of the dough was around 98 °C, a little over baked.

Removing the test bake

Testing the internal temperature of the loaf

With only a little insulation on the oven and only a partial firing today, the oven was cooling quite rapidly, so the test bake was probably done at the best time for baking and the remaining loaves could have done with a little higher vault temperature.

The remaining dough was then put into the oven and due to a very wet dough that wanted to spread out and some very inexperienced oven work by myself, only 7 of the 8 loaves fitted.  These cooked well enough in about 40 minutes, but had a little less oven spring than the first and less colouration of the crust.

The main bake

The final loaf went in on its own and cooking in about the same 40 mins that the main batch took.  So in all there was enough heat in the oven to do 3 batches of bread.

Last few coming out

The test loaf was cooled on about 1.5 hours and then went to the family for testing.  As you can see from the photograph below it turned out exactly how I have been trying to get my bread to be but had never really achieved in a normal domestic oven.  The crumb was super light and soft and the crust nutty and aromatic the sort of bread that you can still taste in your mouth for a couple of hours.  Unfortunately I was only able to save one slice long enough to take a picture. Looking forward to finishing the oven and doing the next bake.

The last surviving  slice of the test bake.