In the 18th century, the Salins saltworks began to show their limits. Production had to be increased to meet the growing demand for salt, especially for the Swiss market, the main client. The saltworks could not, however, satisfy this demand, for reasons both economic and practical:
For one thing, the brines proved to be less and less concentrated, thus diminishing the efficiency of the factory;
In addition, it was increasingly complex and costly to supply the wood necessary to heat and evaporate the brines. The neighbouring forest resources being exhausted, wood had to be brought from further and further away. Transportation costs consequently rose. Some 320 mules and 6,500 horses had to be fed. The roads were often threatened by flooding from the Loue River;
Finally, due to a lack of space, the saltworks could no longer expand, nor could they acquire new and more efficient equipment. Thus they could not adopt the “graduation technique” – a method for increasing the salt content in the brines – that would have reduced fuel consumption.
In 1773 these reasons led the saltworks administration to plan for the construction of a new factory in a more strategic location. The chosen site, situated between the communities of Arc and Senans, had the great advantage of being located next to the Forest of Chaux with its 22,000 hectares. The new site was also on a vast plain, thus allowing the construction of modern buildings of the desired size. Finally, the nearby roadways and waterways comprised a considerable advantage for exporting the salt. Lacking the salt water springs, however, the new saltworks had to be supplied with brine from Salins-les-Bains via a pipeline 21.25 kilometres long.