Producing steam in the oven for the first 5-10 minutes of baking is crucial to making a crusty loaf. This can be done by:
a) Spraying water over the loaf before putting in the oven
b) Put a shallow metal pan on the shelf below that used for baking as oven preheats. When the oven has reached the desired temperature, place the dough in the oven then stand as far back as possible and add a 1cm (depth) of water to the pan creating an instant burst of steam close oven door. Leave in for ten minutes.