[expand]
Seawater Evaporation:
The most accessible method in coastal regions—seawater was collected in shallow pans, then exposed to sun and wind until the water evaporated, leaving salt crystals behind.
The process was slow (requiring days or weeks depending on climate) and weather-dependent (rain dissolved the forming crystals, humidity slowed evaporation). But it required minimal equipment beyond the pans (often simple depressions lined with clay) and produced reliably pure salt.
The solar salt pans were seasonal operations—most productive during warm, dry summers, nearly useless during cold, wet winters. The salt-makers worked intensively during favorable weather, producing quantities sufficient for the entire year.
Brine Springs:
In some inland regions, salt-rich springs emerged from underground—water naturally saturated with dissolved salt from rock layers deep below. These brine springs were extraordinarily valuable, often controlled by powerful individuals or communities, fought over during conflicts.
The brine was collected and boiled—the water evaporated rapidly over fires, leaving salt residue. This boiling required substantial fuel (wood or peat), making it expensive process, but it was faster than solar evaporation and worked regardless of weather.
Rock Salt Mining:
Where ancient seas had evaporated millions of years prior, thick salt deposits existed underground. Mining these required digging shafts, extracting the salt rock, crushing it into usable form.
Rock salt mining was dangerous—shafts could collapse, water could flood mines, the work was exhausting. But the reward was enormous quantities of high-quality salt, accessible year-round, independent of weather.
Some Celtic regions (particularly in central Europe) had significant rock salt deposits, and the mining communities became wealthy, powerful centers controlling essential resource.
Salt from Peat Bogs:
A specialized method: peat saturated with salt (from ancient ocean floors or from salt springs percolating through bog) was burned, and the ash (rich in salt) was dissolved in water, then boiled to extract the salt.
This method combined fuel consumption (burning the peat) with salt production, creating dual-purpose process that was efficient in regions where both peat and salt were needed.
[/expand]