As an adult, he was widely regarded as one of the foremost ironmasters in the United Kingdom. It was while employed at the Yniscedwyn Works, in Ystradgynlais in the Swansea Valley, that he devised the process which would advance the Industrial Revolution. On February 5, 1837, Thomas used a hot blast to smelt iron ore and anthracite coal. The result was an easy method to produce anthracite iron, which revolutionized industry in the Swansea Valley. This type of iron had been patented by Edward Martin of Morriston, Wales in 1804.