Modern puddling was one of several processes developed in the second half of the 18th century in Great Britain for producing bar iron from pig iron without the use of charcoal. It gradually replaced the earlier charcoal-fueled process, conducted in a finery forge.

Puddled iron, a landmark innovation of the Industrial Revolution, was a form of refined iron produced through a process known as puddling. This method involved decarburizing molten pig iron in a reverberatory furnace, which, by stirring with rods, allowed impurities like carbon and silicon to be oxidized and removed.

In this paper we examine quantitatively, using modern thermodynamics and kinetics, this ‘wet puddling’ process, aiming to highlight its originality and importance.

The puddling furnace, a rectangular structure lined with firebrick, was heated by a powerful coal fire. The process began by charging the furnace with pig iron and iron oxide, known as “hammer slag.”

In the puddling process, the oxygen of the air and of the ore or other " fettling" put into the furnace with the iron, combines with and eliminates the impurities, which are afterward...