Decorative plasterworking (including gypsum and fibrous plaster)

Status

Currently viable

Craft category

Other

Area practiced currently

History

Gypsum is a naturally occurring soft sulphate mineral (a crystal of Calcium Sulphate), and has been used for centuries as a type of building material. First discovered by the Egyptians, it was used to create sculptures and architectural elements. The ancient Egyptians mixed gypsum – a soft sulphate material – with water to create a paste that could be shaped and hardened.

The use of plaster spread to ancient Greece and Rome, where it was used to create ornate plasterwork in buildings and homes, and during the Middle Ages, gypsum was used to create frescoes and other decorative elements in churches and castles.

Following a trip to Paris in 1254, King Henry III was said to have admired the whiteness and firmness of walls made using the plaster, hence introducing gypsum to England (where the name ‘plaster of Paris’ comes from).

Plaster became increasingly popular as a building material in the 18th and 19th centuries, in part due to the development of new manufacturing techniques which made it possible to produce large quantities of gypsum at lower costs. Hence, plaster became a common building material across Europe and North America. New technologies and manufacturing methods through the 20th century made it possible to produce high-quality plaster that was fire and moisture resistant – making it a popular choice for both residential and commercial construction.

The latter part of the 19th Century and early 20th Century saw the development of hydrated gypsum, reducing the dying time of plaster significantly from a few days to a few hours. A range of patent plasters were produced using this method, moving interior design into the art deco era. As it does not generally shrink or crack when dry, gypsum plaster is excellent for casting moulds and is commonly used to precast and hold parts of ornamental plasterwork placed on ceilings and cornices.

Gypsum is still widely used as a building material today and is a popular choice for walls, ceilings and other architectural elements, as it is easy to work with and can be painted and finished in a variety of ways. Being made from a natural mineral, gypsum plaster is also a sustainable and environmentally-friendly building material due to its recyclability. Hence, the use of gypsum has endured as a result of its versatility, durability and sustainability.

Fibrous plaster

Fibrous plaster is a form of decorative plasterwork which is composed of plaster of Paris and reinforced with layers of hessian, then secured within a timber framework. It has been used to imitate more expensive and time-consuming traditional lime-based, hand-modelled plaster.

Since the late 19th century, fibrous plaster has been extensively used throughout cultural, commercial, institutional and high-status residential buildings across the UK, evolving in application within modern structures after the Second World War. It is still widely used to make cornices and ceiling roses, in domestic and restorative areas.

Compared to traditional plaster and lath work, fibrous plaster proved advantageous in its ability to produce complex forms with relative lightness, speed of production off-site during building construction and quicker installation. Unlike traditional lime plaster requiring time to carbonate, fibrous plaster can be decorated soon after installation.

Head of the plaster cast workshop at the École des Beaux-Arts in Paris, Frenchman Léonard Alexandre Desachy (1817–1886) patented fibrous plaster in the UK in 1856. Working with architect Owen Jones (1809-1874) in London, Desachy produced the first architectural fibrous plasterwork in the UK in Jones’ St James’s Hall, Piccadilly, London (inaugurated in March 1858). He also worked on the prestigious Royal opera House, designed by Edward Barry (1830–1880), opening in May 1858. This remains the oldest surviving fibrous plasterwork in the UK, while the earliest in Scotland is considered decorative work in the Theatre Royal, Glasgow, in 1880.

With the spread of gypsum plaster after the Second World War, traditional lime-based plaster and fibrous plasterwork experienced a decline. Fibrous plaster was used however to restore some heritage destroyed by the war – including many churches in London. Throughout the 20th century, fibrous plaster was widely used to provide film sets for the cinema industry.

Still today, fibrous plasterwork enjoys extensive architectural usage, including in enrichments and for creating interiors in historic styles.

Techniques

Gypsum allowed more crisp details to be produced being harder than lime, and set before it was removed from the mould. Casting in lime is also more time consuming as the lime has to be used very stiff and has to be punched into the mould
Gypsum plasterboard moulding in traditional cove profile – often used for coving around the edge of ceilings and walls, giving an attractive decorative finish and hiding any joint cracks between the wall and ceiling.
Gypsum can be directly applied over a brick/wood base without requiring a separate finishing. It is also easy to use and level – making it more flexible than traditional plaster variants. Further, gypsum plasters are very lightweight providing greater durability.
Fibrous plaster is used to make very precise ornamental elements such as wall friezes, roses, vaulting and columns. Owing to its multiple possibilities, it is commonly used in contemporary architectural creations, smooth fibrous plaster ceilings and overhead cladding.
Fibrous plaster is lightweight when dry, compatible with traditional building materials, long lasting and extremely fireproof. These fire proofing qualities have often been the reason for its use on plain faced ceilings or where protection of steel was required.
The use of modular cast mouldings allows for a great variety of ornamentation applied in a bespoke way, providing flexibility in design and customisation.
Fibrous plaster provides a flatter, even surface, resulting in a superior finish as it takes paint uniformly.
Due to its superior density, fibrous plaster also acts as an effective sound barrier, providing better room acoustics, and improves privacy between rooms.
Fibrous plaster is hard wearing and long-lasting, providing a timeless and unique look for ceilings and decorative elements.
Made from plant fibres and plaster, fibrous plaster offers thermal insulation and humidity regulation. and also contributing to ecological action and energy efficiency.

Sub-crafts

Pargeting
Stucco
Scagliola

Issues affecting the viability

Low shelf life – gypsum plaster as a material embodies a limited shelf life. It can be kept for around four months, though with taking extra care, this can go up to around ten months.
Costs – for walls/construction, gypsum is more costly than cement for the same thickness level.
Susceptibility to Damage. The hessian backing of fibrous plaster can be susceptible to neglect, accidental damage, damp, and decay which can affect its integrity over time.
Maintenance. Fibrous plaster may require regular maintenance to ensure its longevity. particularly in terms of addressing any issues related to the hessian backing and other vulnerabilities.
Cost. The production and installation of fibrous plaster may involve higher costs compared to other plastering methods. especially when considering the need for skilled labour and specialised materials.