I was having a quick look through “The Welsh castles of Edward I”, by Arnold Taylor, when I found mention of the purchase of 160 pounds of tin for use in the building of Beaumaris castle in Anglesey in the late 13th century.
This naturally had me wondering what use tin was in building works. Tin is a weak metal, and not much use by itself. Almost every use requires it to be alloyed with something else. Lead and tin make pewter, tin and copper make bronze. Actually quite a few nice shiny pilgrim souvenirs and ampullae used nearly pure tin because of that shinyness. But you don’t make them for building a castle, gold and silver are much more popular with the workmen.
You certainly don’t put it in the lead for roofing, that would make it stronger but also less able to be beaten out into shape and around corners.
The last use I could think of would be tinning iron nails or other ironwork. Not only does this make it shiny it also helped inhibit rusting.
Theophilus, writing in the 12th century, recommended tinning iron nails and sheet iron used to bind wood together for making an organ. Biringuccio in the 16th century uses tinning on the inside of bronze or copper vessels to ensure that they do not taint food. He no doubt would have tinned iron as well had it been his job.
I also think that some small or large copper alloy castings were tinned to make them look like silver.
So I think the most likely use of the tin was for tinning nails. I have tinned nails before, using Theophilus’ recipe, but it is trickier than you would think, I really should have another go at it. This photo shows the tinned nails.
You need a deep crucible for the liquid tin, nice clean iron nails, and to get the temperature of the tin and nails just right, as well as a steady hand when dipping them.
Since I wrote this wee post, I have found a mention of using tinned nails in buildings, but cannot recall where I read it.