-
How long was the oven warm before your first bake? I get mine to 250C and leave it there for at least 30 minutes before baking. It needs time to get the oven hot throughout. When you baked your first loaf the oven might have dropped heaps in temp when you insert a cold loaf into the oven, making the actual baking temp lower than the second bake.
In the second bake you had more warm mass in the oven, making it drop less in temp when you add a cold loaf to it.
Makes sense?
I have always followed the Tartine sourdough process which recommends getting the oven as hot as possible then baking at 220c, which I did for the first loaf I baked yesterday as usual and got a pretty disappointing rise. Second loaf went in but when the oven changes setting it defaults to 180c which i forgot to change, the results were amazing, huge rise and perfect splitting along the slash! Had to leave it longer to make sure it was baked through but came out brilliant. What temp do others bake at??? Seems to correspond with the cold oven theory? Should have taken photos but forgot!