I use fine sea salt for baking because it is not iodized. Iodized salt can give an unpleasant taste to baked goods. Also, fine sea salt is easier to measure if you are measuring by volume and not weight, and it integrates more readily into batter than does a coarse salt. Salt is very difficult to measure accurately because it is extremely hygroscopic. It will readily grab water from the air, which will increase its weight slightly. Using the same scale and the same salt, I have found 1 teaspoon to vary between 5.2 grams and 6.6 grams. When you find the level of salt that you prefer, for the most consistent results, always use the same measuring spoon if you are not weighing the salt. But either by weight or volume, in very humid conditions, it may be desirable to add a little extra salt; conversely, in very dry conditions, a little less.