Last night, I ruined a perfectly good dough, a dough waiting to turn into a beautiful bread, by forgetting to provide steam. The bread turned out flat and sad, like an emoticon in gray with a frown and tired eyes. This was a valuable lesson because it is pretty simple to make sure that the oven has steam, in fact, steam sufficient to fool your dough into feeling like it is baking in a professional oven or even a backyard brick oven or in an oven reminiscent of the Roman ovens.
This can get expensive. Easier strategies involve some money, but there are alternatives.
Buy a baking stone or use oven-safe tiles to put the dough (or parchment paper) on. I have heard of using a baking sheet, preferably with parchment paper, but my breads improved significantly when I started using a baking stone. The bottoms of your breads will be equivalent to that produced by the best bakeries.
Perhaps this did not fit in a "steam" essay, but it has to do with crust and, further, what will go on the stone, if anything. I consider a baking stone a must. It needs little cleaning and no other maintenance. Just preheat before baking and keep it in the oven until it cools down. I generally just leave mine in.
Pay the money, about $60, and buy a la cloche. The Wild Yeast blog has instructions to make a DIY la cloche top that will cost a lot less than buying one. Advantage: You get a Roman oven within your oven. The clay bell-shaped contraption covers the dough and becomes a small enough oven that the moisture from the one dough is sufficient for nice oven spring. Disadvantage: Only one bread at a time can be baked, versus maybe two to four without such a space-consuming accouterment. The DIY la cloche mentioned above is small enough for two to fit on an oven rack.
I just use the top of the la cloche over the baking stone. The exception is that I sometimes use an oblong la cloche, the top of which also works well over loaf pans to ensure that sandwich breads get a good rise as well.
As far as steam, dutch ovens do the same thing as the la cloche. They create a small oven within the oven and use the moisture from the dough to produce oven spring during the first 10 minutes of baking. Four caveats: (1) Check the maximum oven temperature for the dutch oven. Mine has a maximum of 475 degrees, but cast iron ones can go higher. (2) Aim seems to be everything: The dough has to be dropped into an incredibly hot receptacle. I have done terribly at this, getting my dough all over the side of the dutch oven, and somehow the breads and their shapes turned out fine. (3) Put flour, seeds, and/or parchment paper at the bottom of the dough so that it does not get stuck in the dutch oven. If it does, wait a few hours for the dutch oven to cool before fighting to liberate the bread. (4) Be careful. The dutch oven gets way hotter than anything else I've put into my oven at the same temperature. I use an oven mitt and a kitchen towel when handling it. Stay calm, breath, and be confident.
The dutch oven produces magnificent results in turns of steam. It retains heat like nobody's business and, in a very small space, efficiently converts moisture to steam to get a rise out of a dough while it turns into a bread. The only disadvantages are the intense heat and the spacial aspect as only one bread at a time can be baked.
Ice or water
Most bread books recommend that either ice or water be used to produce steam in the oven for those first crucial 10 minutes of bread baking. The advice will be to put a pan on the lower rack, underneath the baking stone. Preheat the pan with the oven before baking. I always preheat for an hour to make sure everything I am using - whether a baking stone, a dutch oven, or whatever - is sufficiently hot when the dough goes in the oven.
Immediately after placing the dough on the baking stone, pour a cup of water or ice cubes into the pan. Quickly close the oven door!!! The quicker the H2O is poured and the oven door is closed, the more steam that stays inside the oven and the more steam available to the dough for a lovely oven spring burst of rising.
The advantage of ice is that it is a solid and easier to throw quickly into the pan. It also will not turn to steam - in your face - as quickly. Water can drip. Be VERY careful not to let the water drip onto the oven door because it can crack the glass. Also, the steam from the water can be dangerously hot. These are the reasons why I have only used ice cubes, which, by the way, work quite well.
Disclaimer: I have not tried this. Just intrigued. Many sources recommend preheating lava rocks, the kind used for barbecue, in a pan. They are available at local hardware stores or Home Depot. Pouring water over the rocks just after putting the dough in the oven provides sauna-quality steam. Some recommend pouring a cup of water right before loading the dough as well. Just google "lava rocks bread" and plenty of information will appear at your fingertips.
Dont' cry; eat
The ending to the ruined bread story is a happy one. The freshly ground whole wheat flour infused the bread that hardly rose with such a good taste that I enjoyed the bread and learned my lesson. The bread was dense and not very pretty, but delicious.
P.S. Suggestions from the freshloaf that I have not yet tried - go at your own risk
These are quotes from a freshloaf (bread forum) conversation.
Steamed towel strategy - http://www.thefreshloaf.com/node/20162/oven-steaming-my-new-favorite-way I can get an oven fully steamed five minutes before the bread goes in and then only need to add 1/2 cup of very hot water to the pan once the bread is loaded onto the baking steel. The time the oven door is open is minimal and I don't have to remove a heavy, hot cast iron skillet full of lava rocks after the first part of the bake.I wonder at the safety of putting towels, wet or otherwise, into a hot oven, but there are a few people who have tried this method and they have lived to proclaim its wonders.
Another hot-water-in-the-oven strategy - I find it helpful to preheat the water for two minutes in a Pyrex vessel in a microwave oven before putting it in the oven. It then turns to steam more quickly.
Using an aluminum roasting pan - Inverting an aluminum turkey roasting pan over the loaf "on the stone" with parchment underneath will yield perfect steam results every time (the baking bread creates its own steam).
Spritz the inside of the roasting pan with water before inverting over the loaf - bake the loaf for 10-15 minutes before removing to allow the crust to brown. Cheap roasting pans that come three or four-to-a-pack work great and they're reusable. Center it on the loaf and pooch up the middle of the roaster a bit if your loaf has that much spring (make sure the rim still sits flat on the baking stone's surface).I love this idea; it's cheap, easy, and requires no hot water or heavy equipment. Plus, unlike my la cloche, with its two long, thin cracks, the roasting pan can be replaced for very little cost and will not fall apart when it goes quickly from hot oven to cold kitchen. Cheap and effective go well together.