The tinning industry in the 1840s was relatively new. The basic technology of sealing food in metal cans had been patented in the early nineteenth century, and the Royal Navy had been using tinned provisions for Arctic expeditions since the 1820s. By 1845, tinned food was well established as a provisioning strategy for long voyages, but the manufacturing processes were not standardized in ways that consistently produced well-sealed, uncontaminated product.
The specific manufacturer of some of the Franklin expedition’s tinned goods was a man named Stephan Goldner, who had won a contract from the Admiralty at a surprisingly low price and who delivered the tins — many of them unusually large, holding up to 8 pounds of food — in a compressed timeframe that raised quality control questions. Some of the tins that have been recovered at Franklin expedition sites over the years have been analyzed and found to show signs of poor sealing, spoilage, and lead contamination.
The lead solder question is about the specific method used to seal the tins: solder applied to the interior seams of some tins would have brought liquid lead into direct contact with the food. How much lead leached from the solder into the food, how much food was consumed in a contaminated state, and how much additional lead the crew members absorbed from other sources — the ship’s plumbing, the paint used on the ships, the pewter and lead-alloy tableware common at the period — are all variables that make it difficult to establish a definitive contribution of tin solder to total lead exposure.