Warning: Measure Your Salt
I was a Diamond Crystal baby. Diamond Crystal kosher salt was the only salt my mother used, the only one I knew as a child. Now, half a century later (yikes!), it remains the salt I reach for first — although I now have to fish for it among half a dozen that sit on the shelf. All those fancy sea salts, however, are used to finish dishes or added at the table, where their varied textures are a source of tactile delight. For cooking, I rarely use anything but the kosher salt of my childhood; I can judge, by eye and by feel, how much I need for any task from making a well balanced vinaigrette to seasoning a steak.
I always knew that Diamond Crystal was far less dense than table salt and that it was easily crushed between the fingers. I had a vague idea that these qualities resulted from the unusual shape and fragility of the crystals. The shape meant that in each handful, tablespoonful or pinch there was more space between grains of salt — hence, less salt. The fragility meant that a quick rub of the thumb and forefinger could “grind” the salt for, let’s say, quicker dissolving.
I’d always assumed that other kosher salts were the same. But one day, my supermarket ran out of the Old Reliable and I bought a box of Morton’s. Suddenly, I lost my knack for getting the salt spot-on: everything was oversalted. Everything. Pound cake tasted like something you might serve with pot roast, and pot roast tasted like the barrel-preserved meat served on HMS Bounty. For heaven’s sake, the spaghetti was too salty — I was over-dosing the pasta water.
Even when I figured out what was going on, I couldn’t get it right, which is an interesting if somewhat depressing reflection on the force of habit. And what was going on was this: Morton’s kosher salt is made by a different process, and each unit of volume (cup, teaspoonful, etc.) weighs nearly twice as much as the equivalent volume of Diamond Crystal — and hence contains nearly twice as much salt.
Ordinary table salt is typically made by taking the water out of brine in a series of evaporating pans; its crystals are cubic in shape (remember looking at it through a microscope in science class?). To manufacture its kosher salt, Morton’s runs such salt between rollers, which results in a thin, coarse flake.
By contrast, Diamond Crystal kosher salt is made using a particular open pan evaporating method (the Alberger method, just so you know) which results in handsome hollow pyramid-shaped grains. This hollow structure accounts for the salt’s lightness, and the thin walls of the “pyramids” for its crushability.
So I got out a one-cup measure and a scale, and I weighed similar volumes of Morton’s and Diamond Crystal kosher salts, plus regular table salt, generic coarse sea salt and Malden sea salt from England (included for no reason other than that I think it is the most beautiful of salts). Here’s the outcome, rounded off to the nearest five grams or eighth of an ounce (no, this is not a scientific inquiry):
Morton’s kosher: 250 grams (8 3/4 ounces)
Diamond Crystal kosher: 135 grams (4 3/4 ounces)
Table salt: 300 grams (10 5/8 ounces)
Coarse sea salt: 210 grams (7 3/8 ounces)
Malden sea salt: 120 grams (4 1/4 ounces)
It is the first three figures that we need to pay attention to, because those are the salts we’re most likely to use in our cooking and baking. We learn from them that a tablespoon of Morton’s kosher salt is the equivalent of 1.85 tablespoons of Diamond Crystal — just half a teaspoon shy of 2 tablespoons. We learn that a tablespoon of table salt can be replaced by 2 1/4 tablespoons of Diamond Crystal kosher salt or 1 1/4 tablespoons of Morton’s.
We learn that whenever recipe writers are rash enough to give a precise measurement for salt, they ought to specify what kind they’re talking about. Some do; but even then, some just say “kosher salt” — I’ve done this myself, but I’ve stopped, and I promise never to do it again.
Most important, we learn to add salt with circumspection and to taste at every step of the way. But we all knew that anyway. Didn’t we?