I crack with the blade of a knife (since I generally have one handy to chop whatever else I am including in the dish). I can get a very good crack with minimal force. Since it is such a small break, there aren’t any large pieces of shell to get into the food. I don’t cook recipes that require separating the white from the yolk, so I am not sure how often I break the membrane between the two, but from casual observation, it is almost never.