By 1800 a canal had been built up the Swansea valley and tramroads had also been constructed over the mountains to the north.
This meant that coal, limestone, and iron ore could be brought to the ironworks more easily, and the iron that was made there could be transported by canal to the port of Swansea, and then sent around the world by sea. (See the map on the Story of Iron smelting 1 for the route of the canal).

David Thomas saw a new kind of furnace designed by a Scottish engineer called Neilson. This heated the air that fed the furnace. (See diagram above). Thomas realised that this furnace could work at Ynyscedwyn, thus allowing him to use the hard coal called anthracite from local coal mines.
A new hot-blast furnace was introduced at Ynyscedwyn in 1837, and from then on the works produced top grade iron more cheaply.

More on the story of iron smelting...