The Master Plasterer Whose Ceilings Hang in Stately Homes

Geoffrey Preston, one of Britain's foremost decorative plasterers, has executed ornamental plasterwork for Chatsworth House, Kensington Palace, and numerous National Trust properties. His ceilings, cornices, and relief panels are modelled in lime plaster using techniques employed in English country houses since the sixteenth century.

Decorative plasterwork begins with a full-scale design drawn and approved by the architect. Preston then models the design in clay, creating a three-dimensional original from which moulds are taken. For running cornices, a zinc template is drawn along a guide rail through wet plaster to generate the profile.

The material is lime putty plaster, slaked lime and fine aggregate setting slowly through carbonation. This gradual cure, taking weeks rather than hours, allows extended working time to model fine detail. Lime plaster also remains slightly flexible after curing, accommodating the building's natural movement.

Lime putty is made by slaking quicklime with water and then leaving it alone. Three months is the working minimum; a year or more produces a fatter, more plastic putty that models without tearing at the edges. The set is carbonation, the slow reabsorption of atmospheric carbon dioxide, which proceeds inward from the surface over months and effectively stops below about five degrees Celsius. Decorative plastering is therefore scheduled around the weather in a way gypsum work never has to be.

The substrate is half the craft. Riven laths of chestnut or oak are nailed up with a gap of six to ten millimetres, and the first coat is pressed through hard enough to squeeze out behind them and slump into nibs that hook over the timber; the ceiling then hangs from those nibs. The mix is reinforced with animal hair, ox or goat and traditionally horsehair, well teased out and evenly distributed, which restrains shrinkage cracking and gives the nibs enough tensile strength to carry their own weight.

The enrichment of a ceiling involves applying separately cast ornaments to a plaster field. Each element is modelled individually, cast in a waste mould, and fixed to the ceiling with lime putty and concealed fixings. Joints between elements are worked over while plaster is still soft, creating a seamless surface.

Colour in traditional plasterwork comes not from paint but from the plaster itself. Limewash provides a soft, chalky white diffusing light beautifully. The patina developing over decades gives lime-finished plaster a depth and warmth immediately recognisable and impossible to replicate with modern paints.

The commonest damage to historic plaster is done with paint. Modern vinyl emulsion forms a film that traps moisture in a wall designed to breathe, and the surface blows off in sheets; limewash, soft distemper or a silicate paint lets it dry out. The two fires that reshaped British conservation plastering were at Uppark in 1989 and Windsor Castle in 1992, whose reconstruction contracts required whole decorative schemes to be modelled and cast again and retrained a generation of plasterers in the process.

When commissioning decorative plasterwork, specify lime plaster for its working properties and superior aesthetics. Engage a plasterer understanding both material science and stylistic vocabulary appropriate to your building's period. The investment elevates any room from merely decorated to truly composed. View at https://www.geoffreypreston.co.uk