Charles Goodyear, a hardware dealer, thought that rubber was a good material which required to be modified to avoid temperature induced defects. Goodyear attempted to remove the stickiness of uncured rubber by mixing it with magnesia, then boiling this mixture in lime. Next he attempted to decorate this with bronze powder. but this was not successful. So he attempted to remove the bronze with nitric acid. This led to a mess which was discarded. But a few days later he noted that the surface had lost its sticki-ness. The use of nitric acid nearly asphyxiated Goodyear, but It did lead to some recognition (Barker, 1938) and probably enabled him to hire Nathaniel Hayward (who unlike Goodyear had been associated with the American rubber industry).

It was Hayward who introduced Goodyear to the Idea of using suiphur on, rather than in, rubber: this happend in September 1838. Goodyear encountered many difficulties, both financial and personal, before he decided to try the effect of heat upon a mixture of rubber, sulphur and white lead. An accidental over-heating of one of the specimens produced charring but no melting. When he repeated the process before an open fire. again charring occured in the centre, but along the edges there was a border which was not charred but perfectly cured. Further tests showed that the new substance thus obtained did not harden in the winter cold and was not softened by the summer heat: it was also proof against solvents that dissolved the native gum. He had thus attained the object of his long search.

Obtaining financial and other assistance from William Rider, a New York rubber manufacturer, Goodyear continued his experiments and in 1841 succeeded in making the elastic compound uniformly in continuous sheets, by passing it through a heated cast iron trough. This was the first successful operation of vulcanization as an industrial process. On 6 December 1842, Goodyear had a specification prepared and this was deposited in the Patent Office of the United States as a claim for invention. The application for an English patent was not lodged until 1844, the reasons for the delay being mostly financial.

Public opinion in the United States was still very hostile to rubber, and Goodyear was anxious to interest manufacturers abroad in his discovery. He enlisted the services of Stephen Moulton, an Englishman then resident in the United States, who was about to return to England. Goodyear requested Moulton to take with him samples of his 'improved rubber' to show to appropriate people, especially the Macintosh Company. with the objective of selling the secret of manufacture. Eventually samples reached Thomas Hancock via a mutual friend, William Brockedon (who was to coin the word "vulcanization" for the process).

Hancock immediately recognised the significance of the samples and was able to deduce the presence of sulphur from a yellowish bloom on the surface. He took out a provisional patent on the use of sulphur in rubber and then set out to establish how vulcanization took place. eventually finding out that strips of rubber immersed in molten sulphur changed in character. Hancock applied for a patent for this in November 1843, a matter of weeks before Goodyear belatedly applied for an English patent. Litigation followed which Hancock won.

With the benefit of hindsight Goodyear may appear to have been naive to entrust his samples to Stephen Moulton for transit to England, and Hancock may appear rapacious in his quest for the source of the modification for Goodyear's samples. Hancock's contemporaries tend to support the latter view. Alexander Parkes, the inventor of the cold cure process (using a solution of sulphur chloride in carbon disulphide) marked his own copy of Hancock's Personal Narrative with a note: I think it is a sad thing for Mr Thomas Hancock to try to claim the discovery of vulcanization from the fact of the vulcanized rubber being first brought by Goodyear from America and pieces given to Brockedon, Hancock's co-partner and others

The American Geer (1922) generously noted that Hancock merely attempted to match his competitor's samples and "those of my readers who are chemists in the rubber business, will recognize this as one of the daily demands made upon them". Duerden (1956) observes that at "the time of Hancock's birth (1786) rubber had no applications of any real consequence although its potential was fully appreciated; by his death (1865) rubber manufacture was established as a major industry with a great potential for growth that was to be realized to the full in the years to come".