Isaac Barnes appeared in a Sheffield directory in 1833 as a pen-knife manufacturer in Earl Street.  It is not known if there was a family link with Isaac Barnes, Campo Lane.   By 1837, Isaac Barnes was a pen, pocket, and lock knife manufacturer in Broad Lane.  Barnes advertised in 1839 and 1845, when  he was based at Leicester Street Works, making fine spring knives, sportsman’s knives and dirks.  Isaac was aged about 30 in 1840 and lived with a son, Isaac, aged about four.   In 1851, Barnes employed five men in Leicester Street, where he lived.  By 1856, he resided at Alma House, Steel Bank.   In the 1860s, Isaac Barnes & Co / Sons was listed at Melbourne Works, Suffolk Street, manufacturing table and spring knives.  Isaac later lived in Wharncliffe Road and had retired by the end of the 1870s.  He died at Yeardley Street on 1 October 1885, aged 75, leaving £50.  His grave is at Fulwood.