Friday, September 23, 2011

Starting documentation on the salt experiment

Here's my initial write-up on the salt experiments. I haven't added in all citations yet - but the basics are there. I have more sources, as well, but these 3 are the 'Biggies'.


This small experiment shows how the formation of ‘Fleur de Sel’ (Flower of Salt) differs from ‘Sel Gris’ (grey salt), as well as the general method for harvesting salt.

From the mid-13th century onwards, French ‘Bay Salt’ gained popularity throughout Europe as a cheap, ready source of salt. The English and the Dutch extracted salt from brines and peat, using boiling and burning methods. These were expensive and required capital investments in pans and fuel. The French relied on solar evaporation and the wind to extract salt from sea-water, which was virtually free. (Bridbury)

The sea-water was drawn into long ‘pans’ dug into the ground. These pans were usually lined with clay, sand, cement, or tile, and the water was moved through them, getting progressively more and more saturated with salt as the water portion evaporated. Finally, the concentrated brine was moved to very shallow pans, where the salt began to crystallize.

The first salts to crystallize form on the surface of the water. This is the ‘Fleur de Sel’ – the finest salt, and looks like flakes on the surface of the water. The salt-worker would wait for these to form, and then carefully scrape them off the water, being careful not to touch the sides or bottom, which would disturb sediment and impart impurities to the salt. This task was very laborious, and required skill and practice. Traditionally wooden rakes and scoops were used because of the corrosive nature of the brine. (Bitterman, Bridbury, Kurlansky)

The rest of the brine would also start crystallizing as the water evaporated, forming a crust along the sides and bottom of the pan. This salt is the ‘Sel Gris’, which tended to pick up sediment from the bottom and would form larger crystals. This salt was scraped from the bottom of the pan, trying not to pick up too much sediment.

Because of the hazards of modern sea-water near Texas (the Gulf of Mexico has some serious issues currently), I have chosen to create an artificial salt brine for the experiment. I used Morton’s Rock Salt from a home improvement store. This salt comes in large crystal chunks, and is 99% pure Sodium Chloride (NaCl, or common table salt). I chose to use this over commercial table salt, because of the larger crystals, and because it hasn’t had ‘anti-caking’ agents added, unlike the Table Salt, Kosher Salt, and Sea Salt from the grocery store. The salt was added to unfiltered tap water. This water is considered very hard, and most people use filters to make drinking water. This water is from the Edwards Aquifer, and has only been treated to make it potable.

To make the brine, I added about 1 cup of salt to approximately 3 gallons of hot tap water. I let it sit until just about all of the salt dissolved, leaving crystals in the bottom. I then poured the salt into terra-cotta pans for drying. While the earthen salt-pans were often lined in clay or sand, some were covered in concrete or tile, and I needed a portable pan for this experiment. These pans were left outside to evaporate.

The first crystals appear on the top of the water, because the brine is at maximum saturation. These will form within hours, especially with a slight breeze over the water, which helps with evaporation. As the water is removed a line of salt ‘snow’ forms around the water-line, as the salt is deposited along the sides. If all the water evaporates, the remaining salt forms crystals along the sides and bottoms of the pan.

If the crystals on top are harvested right away, these will be ‘Fleur de Sel.’ The remaining crystals are ‘Sel Gris’ – although because there is no sediment in the pans from dirt and other contaminants, it will appear very similar to the ‘Fleur de Sel’ in this case. Even though the pans appear dry, there is still moisture in the salt, which would be stacked and allowed to dry before being sent to market.

This salt has a different taste from modern table salt, sea salt, and kosher salt. The minerals in the water impart different characteristics to the salt, which are removed in the modern salt-making process.  Different conditions also produce different types of crystals – more wind, and different evaporative conditions in the pan can create very different effects.

In the past, different salts were prized for their different properties – small crystals, different tastes, different colors, etc. The modern salt industry has removed these impurities through industrialization, with the goal of making 99.99% pure NaCl. This is fine for industrial uses, but many of the unique features of ‘local’ salt have been lost, except in ‘Artisan Salt’ available in upscale markets.


Bitterman, Mark. Salted : a manifesto on the world's most essential mineral, with recipes. Berkeley Calif: Ten Speed Press, 2010.

Bridbury, A. England and the salt trade in the later Middle Ages. Westport, Conn: Greenwood Press, 1973.

Kurlansky, Mark. Salt : a world history. New York: Penguin Books, 2003.

Notes about the Experiment:

The 2 large pans were purchased at the same time, from the same place, with the same tags/manufacturer. They differ in their porosity, since the one pan kept all the salt on the inside, while the other drew salt out as the water soaked through the pan, forming the ‘frosting’ on both sides of the pan. I have no other explanation for this phenomenon, since both pans were left outside at the same time, in the same conditions, using the same brine for the experiment.

Large Pan 1:
Large crystals, formed from solar evaporation.

Large Pan 2:
Small crystals, formed from solar evaporation.

Small Pan:
Morton’s Rock Salt, used for the experiments

Glass Jar with Brine:
Following a description from Cato on how to produce a ‘fine salt’, I made a linen bag, suspended the rock salt in it, and left it in the water to form brine. The salt has completely dissolved in the water at this point, and the water is pretty saturated.

Tasting Shells: Feel free to sample the salt and taste the difference!

Shell 1:
From Pan 1, the large crystals

Shell 2:
From Pan 2, the small crystals

Shell 3:
Morton’s Rock Salt, ground to small crystals in a mortar

Shell 4:
HEB non-iodized table salt

Shell 5:
Morton’s Sea Salt

Shell 6:
Morton’s Kosher Salt 

Feel free to comment or make suggestions. This is NOT the final version, but I'll be putting it out tomorrow with my salt-pans for a competition.

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