Salt types and measuring
Table, sea, kosher and flaky salt are chemically near-identical — and a spoonful of each is a different weight, which is where recipes go wrong.
Also called kosher salt (US); sea salt (INTERNATIONAL); flaky salt (UK); iodised salt (UK); iodized salt (US)
For baking purposes the different salts are the same compound. Sodium chloride is sodium chloride, and the trace minerals that give sea salts their character are present in quantities too small to change how a dough behaves.
What differs enormously is CRYSTAL GEOMETRY, and therefore how much salt fits in a spoon. Fine table salt packs densely; kosher salt is coarse and irregular; flaky sea salt is a hollow pyramid that packs barely at all. A teaspoon of each can differ substantially in mass, and salt in bread sits in a narrow useful band as a percentage of flour weight.
So the practical rule is the reverse of the usual advice. The salt you choose matters very little; the way you measure it matters a great deal. Weighing removes the problem entirely.
Iodised salt is worth a separate note: iodine is added at levels intended to be nutritionally useful, and it does not affect fermentation or dough behaviour in ordinary baking.
Composition and specification
Why a spoonful is not a spoonful
Salts differ in crystal size and shape rather than in chemistry, so equal volumes contain unequal masses. Because bread uses salt at a percentage of flour weight within a narrow useful range, a volume measurement can move the effective salt level substantially.
No conversion factor is published here. The ratio between two salts depends on the specific crystal, and quoting one figure would be exactly the false precision this record exists to warn about.
RecordedTrue by definition rather than by measurement
What changes if it is left out
Choosing a different salt changes almost nothing if you weigh it. It changes the effective quantity considerably if you measure by spoon.
Follows from the geometry. The conditional is the whole content of the claim.
RecordedFollows from evidence recorded elsewhere on BakeHQ
"Salt kills yeast" — what is actually true
The claim circulates as a rule and is a statement about concentration and contact, not about salt.
Salt does restrain yeast. It draws water osmotically and slows fermentation, which is why an unsalted dough ferments faster and why salt is a timing control as much as a seasoning. At the concentrations used in bread — a small percentage of flour weight, dispersed through the dough — it restrains without killing, and that restraint is wanted.
What can genuinely damage yeast is direct, prolonged contact with undissolved salt at high local concentration, which is why the traditional advice is to keep them apart when mixing. That is a handling instruction, not evidence that salt is hostile to yeast in the finished dough.
A dough made without salt is not a faster dough. It is a flatter-tasting, harder-to-time dough that over-ferments while you are not watching.
Related
What it does
Flavour contribution
Salt changes how other flavours are perceived, which is why unsalted bread tastes flat rather than merely unsalted.
Covered in
What flavourings actually do, beyond tasting of themselves
The one flavouring on the page that is not only flavour: it slows fermentation and changes how the dough handles.