Sharp lame, good slashing = better oven spring
I tend to economize on razor blades for slashing, using them quite a few times before throwing them away. I think I've been handicapping myself. I used a new blade for the last batch of ciabatta, and got aggressive with the slashing -- 1/4 inch deep, at a 45-degree angle to the surface of the boule. Result: great oven spring. My slashes expanded a whole inch, rather than the usual anemic 1/4 inch or so.