Isaac Theatre Royal revives ancient skills

The heritage restoration of the magnificent ornate plaster ceilings and interior of Christchurch’s Isaac Theatre Royal, which re-opened yesterday, is the result of a collaboration of four South Island specialist fibrous plastering companies, an ancient skill that lives on strongly in New Zealand. The Isaac Theatre Royal restoration highlights the age-old fibrous plaster manufacturing process of creating moulds, pouring in plaster and reinforcing it with canvas, wire or threads. In more recent times fibre glass has become the main strengthening factor.

Fibrous plastering has been around for more than 9000 years dating back to the Egyptians. In New Zealand it was a common building technique during this country’s colonial development in the 19th and 20th centuries, but over the last 30 or 40 years it has largely been replaced with mass produced plaster board and other more modern materials.

The number of fibrous plastering companies in New Zealand has declined over the last few decades, but those that do remain are increasingly in demand for heritage and restoration work.

The restoration of the historic Christchurch theatre was a massive job that needed a broad range of fibrous plastering skills and the collaboration of Plaster Services, Plastercraft Southern, Hush Interiors from Christchurch and Seddon’s: The Fibrous Plaster Company from Dunedin.

The contract for the Isaac Royal Theatre was held by Plaster Services, which has specialised in heritage work and has been involved in restoration of theatres and public buildings throughout New Zealand for the past 40 years.

Gary Watson from Plaster Services said the auditorium and foyer had sustained damage ranging from minor cracking, distortion and separation through to large sections of lath and plaster mouldings lying on the ground. The traditional organic fibrous materials of hessian and sisal has a normal life of 80 years and this made the reinstatement of some of the heritage plaster impractical due to its structural fragility. Plaster Services salvaged, catalogued and stored all of the plaster mouldings, decorative element samples and profiles. Plastercraft Southern Ltd made moulds and remanufactured all the plaster elements throughout the auditorium including the 12 metre diameter dome collar, proscenium arch and royal box towers. Installation was then then carried out by Plaster Services back to its original appearance.

Mr Watson said modern moulding compounds produce casts with fine, sharp relief, undercut decoration, piercing and inlays, and modern plasters have increased strength, lightness and flexibility.

Dunedin-based Seddon’s: The Fibrous Plaster Company was responsible for casting the fibrous plaster ceilings and beam encasements, plaster cornices, circular domes and mouldings to the foyers. Seddon’s have operated from Dunedin for more than 60 years. They were tasked with putting the broken pieces together, taking moulds and then casting the new sections. Seddon’s have restored many ornate heritage ceilings in cities throughout New Zealand and farm houses throughout the South Island.

Ceiling specialist Hush Interiors, from Christchurch, was responsible for designing and installing the seismic grid which holds the plasterwork in place and ensuring it is built to a standard that meets modern earthquake codes of compliance. This part of the job was recently recognised by the Association of Wall and Ceiling Industries (AWCI) with a Heritage Award at the association’s annual conference in Queenstown.