DIY Steam Injector

[Duncan Werner]

This is in response to a question from tikidoc, when I made passing reference to building a steam injector for my oven.

I used to do a lot of baking; not just bread but pastry as well. I don't do that too much anymore, outside of pizza (a topic in and of itself), but I was pretty heavily into bread for a long time.

I knew that commercial kitchens used steam injectors for bread. I assume anyone reading this knows why; but briefly, it delays formation of the crust and, while the dough is gelatinized, allows for more expansion, resulting in a better crumb. The question is how to do this if you have a stock oven.

An old Ed Giobbi book I read (I only remember the cover, it might have been this one) suggested throwing some ice cubes in the oven to get this effect. I never had good results with that. Peter Reinhart (BBA) suggests using a spray bottle, and I used that to make some pretty good baguettes. The best result I had was using the Jim Lahey method (also suggested by Chad Robertson) which uses a big Le Creuset dutch oven to retain steam. In that method wet dough plus a tight seal on the pot results in a good steamed loaf, but it has to fit in the pot: hence it only works for a boule or similar shape.

To make baguettes or other breads, the Reinhart method is the best, but it's a little clumsy and you have to open the oven which lowers the heat. So I decided to build a steam injector, or as close as I could.

I should note that what I built was really a spray injector, not a true steam injector; like the spray bottle method, it sprays a mist of water and assumes that the heat of the oven will immediately transform it into steam.

The major problem with doing this is heat. If you could build it out of plastic or rubber that would be easy; but most plastics won't stand up to a 400F oven. The trick is to use metal parts inside the oven, but not to transfer the heat out. What I used was a threaded ceramic tube, which I could connect to a standard pipe (under the oven) and a rubber hose (outside) and which acted as an insulator.

Here's what I used:

A pressure spray bottle. These are available at most hardware stores. They work on the same principle as water squirt guns; you fill them with water, then pump in some air, and they're pressurized. Then there's a valve, usually with a finger trigger, which pumps out the liquid.

Some plastic tubing, plus connectors. Depending on the pressure bottle, standard pipe fittings should work. The plastic tube runs from the pressure bottle to the next part, the insulator.

An insulator. This is key, or you'll either melt the plastic tube or start a fire. I used a ceramic pipe, but these are hard to find. The idea is to separate the "hot" parts from the "less hot" parts.

Metal pipe. I ran this under the oven. It turns out there are a lot of holes under there, some of them used for wires. I learned this while changing an ignitor. I suppose it depends on the oven, though. I ran a pipe from just behind the door, on the side, through to the main oven, and bent it so it aimed at the side.

An airbrush nozzle. This was really important, because it mists (aerosolizes) the water when it comes out of the tube. Unlike a simple spray bottlle, though, these are made of metal - brass, aluminum, steel. You can get a steel one for just a few dollars. I had to thread the inside of the pipe, but there may be connectors available.

So the end result: press the valve, get an injection of mist which turns into steam. And great baguettes.

Sorry for the long post. I'll try to dig up some photos, unfortunately I think they're all stuck on old phones.

[tikidoc]

Wow, thanks Duncan. I need to think about doing this!