Tuning your oven

Written by Warwick Quinton. Posted in Baking Tips and Tricks

(or 'how to get a better bake')

Bakery Rack 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 relevant 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. Then, we look to achieve a good crust colour - not just brown, but golds and reds too. The first part, eveness, is to do with positioning. Crust colour is to do with steam, and also thermal mass.

 

 

 

Positioning your bread in the oven

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.

 

ThermometerAs 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. Now, 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.ermal 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. However, I'll be discussing the effects of thermal mass later in this article.)

 

Bread set on stones

It's important to make any adjustments one change at a time. Like any scientific process, you need to isolate the changes, or knowledge gained will be worthless from a scientific perspective. 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.

Oven sealing for better steam

 

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 steam 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 are they missing? Obviously, if your oven is new, this usually won't be a problem - but older ovens wear seals down, so check the condition of them visually first. Next, after pre heating the oven, run your hand around the edge of the door while the oven door is closed - about a centimetre away from where the door meets the body of the oven. 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 usually couple of options open to you as to how to go about fixing oven seals. The first, and often the most difficult option, is to replace them with the manufacturer's replacement product. It can be hard to find specific parts for specific ovens - be warned. However, this may be the only workable solution, particularly if the oven is fairly new, or high tech, because there are sometimes quite unusual and complex ways the manufacturing engineers have gone about sealing in the heat.

The second option is easier, but a bit more 'back yard' - and I'm definitely not officially recommending it. Having said that, IT USUALLY 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. This rope is capable of absorbing high temperatures, so it's very suitable for wrapping around the door cavity of an oven. 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, alternately, an auto parts shop, will have high temperature silicone or cement, sometimes known as gasket silicone. When you get home, 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. The ceramic rope, sometimes called 'tadpole gasket', will press flat when the oven door is closed, 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. An energy saving is always a good reason to do this job - so the benefits add up.

Creating steam in the oven

[Spraying the oven walls to generate steam] 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, especially if the source of heat - the element or gas flame - is under the oven.

 

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, especially if the source of heat - the element or gas flame - is under the oven.

 

I've also sprayed the walls of the oven to get a quick surge of steam - but this evaporates quickly, and loses heat in the oven while the door is open.

 

Instead, try positioning an oven rack just below the roof of the oven, then putting a large tray or bowl, filled with water, on this rack. The top of the oven is hot enough to boil the water, and thus generate lots of steam - without affecting the sole heat in any way.

 

You will notice a huge difference in the colour of your crust once you have greated adequate steam in your oven. The crust will also be thinner and have a better 'mouth feel' as well.
Increasing Thermal Mass

 

Woodfired oven

 

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 back into the baking box. This has the advantage of heating up the oven air space quickly, but once this material is full up with heat, it simply leaks out, almost like it wasn't there.

Domestic ovens, I have found, are designed to work for an hour or two very efficiently, and then they become rapidly less efficient. These ovens tend to cook the bread from the outside in, and so they take a while to cook a loaf, and twice as long to cook two. If you have ever had to bake a few successive loads of bread in one of these ovens, you will also notice that the baking characteristics change dramatically between the first load and the last.

 

Truly great crust and consistent baking temperature comes from heat that is generated through a large thermal mass, rather than the convective heat I have just described. In large commercial 'setter' type ovens (see picture below), there is a lot more thermal mass.

In bakery ovens, thermal mass can be increased by the use of stones, or large cavities filled with oil, air, or by specialist insulation, which are external to the baking chamber itself.

Ovens designed to bake using thermal mass, rather than to bake using convective heat, make steady, 'thick' heat. Once the heat is there, they cook bread very quickly indeed.

They also achieve more subtle crust colours, due to the intensity of the heat cooking the whole bread through at once, rather than from the outside in, as mentioned earlier.

Commercial ovenIt's hard to describe the effect that a large thermal mass has on baking chunks of dough. Bread cooked on the sole of an oven designed with a large thermal mass 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, 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 - and it is more pronounced than when 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.

For example, after you have baked your bread, you can use the oven for roasting meats and vegetables - then, as it cools, the oven can be used for making reductions for sauces. If you still have heat, you can use it for drying fruits and vegetables.

Adding thermal mass to a deck

(At the SourdoughBaker Cafe in Hunter Street, Newcastle, we utilised the heat left over after baking to do all of these things - and because we had so much retained heat, due to Bertha's huge thermal mass, we also used this heat to dry out our waste food scraps to make coal, which we then used to start the fire the next day!)

Our next kitchen in Denison Street Newcastle West already had an oven, which was an old gas fired caterer's oven. The photo here shows how I've added bricks inside the deck to get better crust colour and a faster bake. The bricks at the bottom of the deck are there to set the dough directly onto for baking 'on the sole'. This has also reduced the crown height, making it a more specialised baker's oven, no longer ideal for a caterer.

By increasing the thermal mass, we reduced the baking time by about 50 percent, and by continually increasing the mass, both internally and externally, we have been able to get bright orange crusts on our breads, which before tuning was impossible. I have owned and used many ovens over the years - most bakers just 'make do' with their oven as it is - but learning to improvise has been invaluable.

The picture at right shows the same caterer's oven surrounded by bricks, which have then been wrapped in reflective insulation to make the most of the heat absorbed by the external layers of brick.

The oven has increased in size by over twenty percent, and weighs easily three times what it did. It also bakes excellent bread on the sole. The bricks stay hot for many hours - the more the oven is used, the more efficient it becomes.

Typically, we bake small volumes through this oven, about 16 to 24 three quarter kilo loaves every hour. Before tuning the oven, the oven was averaging only 8 to 12 of the same sized loaves per hour, with less appealing, thicker crusts. This was because each load extracted more heat from the oven, progressively slowing it down further and further. We had to allow the oven to recover for a period of time between loads, which is no longer the case. We can now drive the oven at 100% capacity almost constantly.

Why tune an oven at home?

These days, modern ovens are technically more sophisticated than they once were, with more features - your oven may defrost, preheat, be able to be programmed, grill, rotisserie, toast and even bake.

They are a swiss army knife for the kitchen, doing everything you could possibly need. They are sold to be more energy efficient than they once were, and easier to clean.

In short, they can do everything adequately.

But if you want to bake cakes or bread, or slow roast, or make great pizza - tuning an oven can really make a difference. And tuning can be as simple as adjusting the shelves to find the center of the heat. Or, as I've mentioned in this article, it may involve improving the oven seals, generating steam, or increasing the thermal mass of the oven itself.

If you want to bake on the sole, or if you wish to make superior tinned bread, or if your oven is older and in need of some TLC - tuning is going to dramatically improve what comes out of the oven. It will help you to better understand your oven, and the oven will provide steadier, more predictable heat.

Want to know more?

If you are interested in this subject and want to read more about ovens, have a look at these articles:

How to Use an Oven Properly

Baking bread in the back yard barbeque!

Building Bertha, the woodfired oven.

Wood Fired ovens for baking bread

As always, Happy Baking!

 

 

 

 

 

 

 

 

Breadmaking Classes