Open Pan Salt Making

The opportunity to try making salt from sea water, following the same technique used for centuries up and down the Forth coastline, presented itself recently. Here is an illustrated step by step guide to the process, from water collection to the creation of fine sea salt, as it might have been done at the salt works at both Drummochy and at Viewforth. 

90% of Scottish salt was made along the edges of the Firth of Forth and in the late 18th century Fife's best salt was said to come from three works: "Drummachie, Largo and St Monance", largely because of the salinity of the water they were able to draw on ('The Salt Industry and its Trade in Fife and Tayside' by C.A. Whatley).

The 1/3 scale custom-made salt pan shown in the photograph was made for the 1722 Waggonway Project and it is based in the garden of Cockenzie House in East Lothian. A traditional salt pan was typically 18ft x 9ft and 18 inches deep.

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The stainless steel pan above (which would have been iron in the past) sits above the furnace, in which wood was burned throughout the process (although coal would have traditionally been used). Industrial salt pans would have been within roofed buildings to protect the salt water from the rain, which of course would have diluted the salt water and interfered with the process. Here is the process followed at this experimental salt pan, with numbered illustrations....

​1. sea water is collected from a tidal reservoir in the rocks near the shoreline (often referred to as a 'bucket pot' because originally buckets were used to collect the water - although pumps and windmills were often used later).
2. the water is poured into the pan which is hot from the fire beneath it and evaporation begins.
3. prior to boiling, egg white is added to the warming water in order to gather up any impurities (in the past blood was sometimes used rather than egg white).
4. the resulting scum can then be skimmed off the surface.

Once the water has evaporated to a suitable stage and some calcium carbonate (known as powder scratch) has been removed, more sea water is added and the process is repeated, including the addition of egg whites and skimming off of the scum. Further sea water is added two more times and the process repeated so that four boilings are carried out in total. With each boiling the salinity of the water in the pan becomes more concentrated. All the while, the furnace has to be attended to (historically six or more tons of coal were used to produce one ton of salt). Finally, after around 8 hours (or 24 hours on a full size pan) the water fully evaporates, leaving salt crystals on the pan surface.

The images below illustrate:

5. calcium carbonate separating from the water
6. a salt crust appearing on the surface while the remaining water simmers below
7. the residual water evaporating through cracks and holes in the salt crust (furnace heat is low at this point)
​8. the hot salt being drawn to the sides of the pan to drain briefly before being transferred into baskets and stored in the girnel (storehouse). 

The whole process done in this replica 1/3 size pan took eight hours and yielded 4 kg of salt. The process was clearly inefficient - using huge amounts of fuel and requiring much human input. It's not surprising that salt production took a downturn by the early 19th century. The arrival of imported rock salt and the repeal of salt duties in 1823 sped up the decline. Once a necessity of life - to preserve fish and meat and help people to survive the winter months - and a significant industry on both side of the Forth - the salt industry is an important part of Scotland's (and Largo's) history. 

Image: Illustrated London News 24 August 1850