Because the exhibits are so small in scale, there is a possibility that a fascinating show currently running at Kilkenny's Rothe House may be overlooked by visitors to the city's annual arts festival, beginning next weekend. This would be a great pity since the exhibition of Irish miniature portraits is the most extensive yet to be held in the Republic. There are 120 examples of the form on view, the earliest dating from 1621 and the last from 1837. The exhibition's core is devoted to Kilkenny artist John Comerford (c.1770-1832), but all the most familiar Irish miniaturists are also represented.

A thorough catalogue accompanies this show, with the introductory essays and individual entries written by Paul Caffrey, who has studied this particular field in Ireland. He writes that miniatures may be divided into two categories, the first being those designed to be worn as a piece of jewellery. The sitter's portrait would usually be enclosed in a precious metal casing, which might also contain a lock of hair or the subject's initials. Such miniatures acted as commemorative items to be given away to someone connected either by marriage or close ties of friendship to the sitter.

Alternatively, a miniature could be hung on the wall, most commonly in a private, informal room, to be seen only by a few people; even today, such miniatures are collected to be arranged in groups as a form of interior decoration. There were also two principal techniques that are used to produce miniatures, the more complex - and therefore less popular - being the enamel method, in which paints would be applied with metal oxides onto a base and then fired individually in a kiln.

Less time-consuming was the application of watercolour onto ivory, a form probably originating in Venice and popularised by the 18th-century Italian artist Rosalba Carriera. The watercolour miniature is by far the most common type and there are many examples of it in the Kilkenny show. Particularly during the 18th century, a substantial number of artists in Ireland made their living and reputations through miniature painting. Among the most familiar of these were Nathaniel Hone the elder and his son, Horace Hone, Thomas Frye, Luke Sullivan and Adam Buck.

The catalogue for the Kilkenny show lists more than 200 such miniaturists who worked in Ireland. In addition, several important exponents of the form came from overseas to work here, the most famous of these being George Chinnery, who moved to Dublin in 1795 and remained in the country until 1802.

He appears to have had a particularly important influence on the career of John Comerford, who, after working in his native Kilkenny, came to the capital around 1797, when he advertised his work in a local newspaper. He first exhibited miniatures in Dublin in 1800 and immediately received favourable reviews, the Dublin Evening Post writing that "Comerford seems to play with his art in all the strength, the ease and the variety of the most vigorous and commanding genius".

Paul Caffrey summarises the artist's particular characteristics as including russetbrown shading on the sitter's face which is always finely drawn and modelled with grey hatching to produce a soft effect, as well as the use of gum arabic for painting clothes to give flat areas of colour. Comerford enjoyed a highly successful career as a miniaturist; in an appendix to his catalogue, Paul Caffrey carries a dauntingly long list of his sitters, covering just about everyone of note in early 19th-century Ireland. He also had a number of pupils such as Samuel Lover and John Doyle. He seems to have been not only productive but prudent, leaving, it was reported, the sum of £16,000 after his death.

John Comerford died in January 1832 and by that date the great period of interest in miniatures was drawing to a close.

The exhibition, John Comerford and the Portrait Miniature in Ireland c. 1620-1850 continues at Rothe House, Kilkenny, until Sunday, August 29th, after which there are plans for it to travel to the Hunt Museum, Limerick. The accompanying catalogue by Paul Caffrey is for sale at the exhibition for £10.