Tuning your Oven

Like a guitar, an oven can be tuned. This process is probably more relevant to the frequent baker, rather than the occasional one - and certainly for the commercial or semi commercial baker, working with less than perfect equipment. It is also relevant if you are particularly interested in sole baking, because getting really decent bread baked on the sole of the oven can involve a lot of hit and miss.

The basics of oven tuning

Tuning the oven involves, at its simplest, getting the bread to cook evenly - top, bottom and sides. In most cases, finding the true 'baking center' of the oven is the most important step. Sometimes this is as easy as moving up or down the shelves of the oven. To do this effectively, of course, you'll have to work out where the heat is coming from. If it's coming from the bottom of the oven, which is quite common, moving the shelf up will have the effect of making the top of the bread cook more quickly, while moving it down will cause the bottom to cook more quickly. Top heat in the oven, that is, if the heat radiates from the top, has the opposite effect.

Ovens that heat from the side or back are often fan forced to compensate for this. In most cases the fan does a great job, and without it the oven is quite uneven. I generally leave the fan running in these ovens, because the first stage of tuning is really all about getting the top and bottom of your loaves baking at the same speed. You can always rotate or position the bread to deal with unevenness of back or sides. More on that later.

As a starting point, you want to position the bread as close as possible to the center of the oven. Allowing for the height of the loaf, you will generally start with the shelf of the oven slightly lower than the center. Bake a loaf at about 180 degrees celsius, and when done, have a look at the top and the bottom. Are they about the same colour, or did the top cook quicker? From here you can adjust the shelves up or down to find the most even baking position, as mentioned earlier.

Clay bricks, pavers and oven stones can be used at the top and/or bottom of the oven too - especially if you are wanting to get into 'sole baking'. These will increase the thermal mass of the oven, as well as change the colour of the crust. They can also be used under the base of the bread for 'setting' your ripened dough. Adding them changes the dynamic of the oven considerably. I suggest attending one of my regular classes at the SourdoughBaker Kitchen, where we cover more on this subject in detail.

It's important to make any adjustments one step at a time. Like any scientific process, if you change two things at once, you will never know which things you've changed worked. So if you move your shelf, make sure you bake a loaf exactly the same as last time when you test. If it is baked in a tin, make sure you use the same tin, same recipe, same baking time and so on.

Steam and oven sealing

To get the crust of your bread looking beautiful, you need steam. When the bread begins to cook, moisture leaves the dough, thereby creating steam. In an ideal world, this is enough to give your crust a golden brown colour - but when you bake a loaf at a time, there often isn't enough steam generated to achieve this. In addition, many ovens lose moisture due to poor oven seals.

Firstly, check the seals of the oven visually. Are they worn or missing? Obviously, if your oven is new, this won't be a problem, or won't appear to be a problem. Then, run your hand around about a centimetre away from where the door meets the body of the oven when the oven is running. You will feel heat being emitted if the seals don't work properly, and quite possibly there will be places where the heat is stronger. If so, you will need to do something about the seals - apart from the fact that the bread won't crust properly, you will also be costing yourself money in lost heat!

There are a couple of options as to how to go about fixing oven seals. The first, and sometimes the most difficult option, is to replace them with the manufacturer's replacement product. This can be quite difficult, but may be necessary, particularly if the oven is fairly new, or high tech. The second option is easier, but a bit more 'back yard' - and I'm definitely not officially recommending it. Having said that, IT WORKS.

Go to a shop that sells woodfired heaters, or a decent BBQ specialist. They will often have various thicknesses of ceramic rope, which is what is commonly used to insulate the door seals of woodfired heaters. Get about a metre or two of a thickness that roughly corresponds with the the thickness of the existing seal on the oven. The same shop, or an auto parts shop, will have high temperature silicone or cement, sometimes known as gasket silicone. Simply glue the ceramic rope around where the old seal used to be on your oven - this will either be on the opening or on the door itself. This seal will press flat and seal remarkably well. Once this is in place, again run your hand around the edge of the oven door when the oven is heated, and assess whether the heat is staying in. If you've done a good job, you won't feel any heat coming out.

Once your oven is properly sealed, it will bake more efficiently, particularly if you have a turbo forced oven.

The next thing to do is to make steam in the oven. The objective is to be able to generate as much steam as possible, while not affecting the dynamic of the oven too much. I've used trays of water on the floor of the oven many times, and while this works, there is a chance that the tray of water will reduce the sole heat available to the bread. Try positioning an oven rack just below the roof of the oven, then put a large tray or bowl on this rack. The top of the oven is hot enough to boil the water and thus generate lots of steam.

Increasing Thermal Mass

Most domestic ovens have very little thermal mass - they rely on thin sheets of ceramic fibre (like household roofing insulation, only rated to a higher temperature) to get heat to reflect into the baking box. This has the advantage of heating up quickly, but once this material is full up with heat, it simply leaks out. Domestic ovens, therefore, are designed to work for an hour or two very efficiently, and then they become rapidly less efficient. They tend to cook the bread from the outside in, and so take a while to cook a loaf or two. As such, they make a darker crust, as the heat takes longer to cook the dough, and comes from reflection.

Great crust comes from heat that is generated through a larger thermal mass, rather than just convective heat. In large commercial 'setter' type ovens (see picture below), there is a lot of thermal mass - either through stones, thick insulation or oil filled cavaties. These ovens make steady, thick heat. Once the heat is there, they cook very quickly. They also achieve more subtle crust colours, due to the intensity of the heat cooking the whole bread through more quickly.

It's hard to describe the effect that a large thermal mass has on baking chunks of dough - but the closest thing I can think of is the heat is 'thicker' than convective heat alone. Rather than the dough cooking from the outside to the inside, bread cooked on the sole of the oven cooks through almost all at once. The last thing to cook is the crust - and you can see the crust 'colouring up' towards the end of the baking cycle - and by that stage the dough has fully expanded, or in baker's language, it has 'kicked'. This 'kick' is the best thing about baking on the sole - it is more pronounced than cooking in tins.

Increasing the thermal mass in your domestic oven does mean that it will take longer to heat up initially, and therefore may increase your energy bill. However, if you manage your baking day well, you can use the heat generated for a variety of tasks. After you have baked your bread, you can use the oven for roasting - then as it cools the oven can be used for making reductions for sauces, and if you still have heat you can use it for drying fruits and vegetables. This is what we do with our woodfired oven in the SourdoughBaker Cafe - and because we have so much retained heat due to Bertha's huge thermal mass, we also use this heat to dry out our food scraps to make coal, which then starts the fire the next day!

(This article is still being completed.)

Building Bertha, the woodfired oven.

Bertha is our woodfired oven. She lives in the SourdoughBaker Cafe, in West End, Newcastle. My mate Craig Miller and I designed her from scratch. There's more about that story on one of my blogs,  so I won't repeat it here. But if you are interested in SourdoughBaker Cafe, and it's oven, and other stuff, have a look at this blog too..

Bertha is a bit of a rarity - she's much bigger than a domestic woodfired oven (typically an AGA or Wamsler or even an Early Kooka), though she follows similar principles from a design perspective. She has two decks for baking bread, and a third below them which is effectively a 'heat bank'. There are two fireboxes at one side, one above the other. These fireboxes produce the heat for different parts of the oven. The top one heats the top deck and the cooktop, while the bottom one heats the lower deck. Each deck provides about half a metre deck space, upon which we can set up to twenty loaves or so at a time.

Most bakery style woodfired ovens have the fire set inside them, or are 'scotch' ovens, which have a separate firepit below the baking deck. Ours is a different beasty altogether, with a completely contained firebox joined to the baking deck. Thus, the heat travels via conducted means through brick, rather than via convection first, as is the case with the two ovens mentioned here.

To those of us who have not completed degrees in thermal engineering, having the heat enter the baking chamber via thermal mass, or conduction, makes for a whole different type of baking. The main feature of heating a baking deck using thermal mass is its steadyness - once the heat is in the deck, it stays there for a long time. In effect, we have been able to minimise the 'falling' effect of most woodfired ovens, making Bertha ideal for round the clock use.

But wait, there's more. As any old time baker will tell you, there's the crust. That's what this is all about. The crust produced via an oven with a large thermal mass is far superior to the crust from any other oven. Bread from a brick oven is just very special. You can get good crust in other ovens too - oil filled ovens, and gas fired setter ovens for example - but brick is a unique material with unique qualities. Hence, unique crust. Anyone who has eaten bread from a woodfired oven on a regular basis will be able to verify this.

I'll be adding to this article very soon, but for now I just wanted to give you a bit of a taste of my latest passion...

Wood Fired ovens for baking bread

Sooner or later, most home bakers either experience someone else's home made wood fired bread, or just get the bug to experiment. Or, they might simply visit an actual woodfired bakery, and are either inspired or awed or both.

Driving a woodfired oven is something akin to flying, only you are kind of 'surfing' heat. Baking with a wood oven, which has substantial thermal mass, is often referred to as baking on a 'falling' oven. That's because the oven is fired till the insulation or core is very hot - often above 500 degrees celsius - and the oven is then used to bake throughout the temperature's long 'fall'. Typically, the baker would begin with pizza and flat breads like focaccia; then baguettes and rolls - things with a small mass, which cook quickly and fill the oven with steam. Then up to viennas, batards, and the tinned loaves. Finally, fruit breads, cakes and biscuits, which need lower temperatures. The remaining heat was then used to prepare vegetables and other general tasks.

In effect, the baker's art when using one of these is all about what to bake when.

Your domestic oven will either be gas, electric, or possibly even wood fired (the latter if you are baking obsessed, or if you live in a cold climate and have a fuel stove). And of course, lately I see lots of 'patio based' manufactured wood fired ovens. These look like good fun. But that's for another article! For now, I'd like to help you set up your oven for baking bread at home.

Sourdough Breadmaking Classes and Workshops

If you like the site, and would like to have me come to your venue or kitchen to conduct sourdough breadmaking workshops with your group, have a look at the options and ideas for breadmaking workshops and demonstration classes while you're here.