Plaster vs polyurethane ceiling roses and mouldings: an honest comparison

Plaster ceiling roses and mouldings give the crispest detail and the most authentic result in a period home, and they take paint beautifully once sealed. Polyurethane is lighter, cheaper, easier to fit and copes better with damp. Polystyrene is the cheapest and lightest of all, but its detail is soft and it marks easily. The right choice depends on the room, the house and the budget.

I make things in plaster, so I have a bias. I will try to be fair anyway, because each material does some jobs well.

The three materials

• Plaster. Gypsum plaster cast in a mould, sometimes reinforced with fibre or hessian scrim in larger pieces. The same family of material used for decorative ceilings since the eighteenth century.
• Polyurethane. A dense rigid foam moulded under pressure. Usually sold pre-primed, often in long lengths for cornice.
• Polystyrene. Expanded polystyrene, the light white foam familiar from 1970s ceiling tiles and coving.

Detail and crispness

Liquid plaster flows into every corner of a mould before it sets, so it picks up fine edges, deep undercuts and sharp arrises very faithfully. Good polyurethane also takes detail well, and the best high-density products are impressive. Edges tend to be a touch softer, and deep undercuts are harder to achieve. Polystyrene has a granular surface and rounded detail, which shows up clearly under a raking light.

Light is the test. A ceiling rose is lit from below and from the side, and shadow is what makes ornament read. The deeper and sharper the modelling, the more the piece comes alive.

Ornament is drawn in shadow. The sharper the edge, the darker the line.

Weight and fitting

This is where the synthetics win. Polyurethane and polystyrene are very light and can be fixed with adhesive alone in most cases. They cut with a fine saw and are forgiving for a first-time fitter.

Plaster is heavier. It needs a good adhesive and, for a rose, mechanical fixing with screws into the joists. It is more brittle, so it must be handled with care before it is fixed. None of this is difficult, but it does take more preparation. Our guide to fitting a plaster ceiling rose walks through it.

Painting

Raw plaster is porous. It needs a sealing mist coat of thinned emulsion, then it takes ordinary emulsion well and holds a soft, matt finish that suits ornament. It can be repainted many times, and old paint can be cleaned out of the detail if it builds up.

Polyurethane usually arrives primed and takes water-based paint easily. Polystyrene needs care: solvent-based paints and some adhesives attack it, so water-based products are the norm. Both synthetics can look slightly plastic under a sheen finish. A flat or matt paint helps.

Authenticity in period homes

Georgian, Victorian and Edwardian ornament was made in plaster, either run in place or cast. In a period house, plaster looks, sounds and ages like the surrounding ceiling. It also moves with the building in a similar way. If a matching piece is replacing a lost original, plaster is the like-for-like choice.

In a listed building this matters more. Changes to the character of a listed interior can need listed building consent, and conservation officers generally favour traditional materials for repairs to historic fabric. It is always worth asking your local authority before you start. Our history of the Victorian ceiling rose shows how central plaster was to those interiors.

Moisture, cost and which to choose

• Moisture. Polyurethane shrugs off humidity, which makes it a sensible option for bathrooms and other steamy rooms. Plaster is fine in a well-ventilated room once painted, but should not be soaked.
• Cost. Mass-produced polystyrene is the cheapest. Polyurethane sits in the middle. Plaster, especially hand-cast to order, costs more because of the material, the weight and the hours each piece takes.
• Durability. Plaster is hard on the surface but can chip if knocked. Polyurethane resists chipping. Polystyrene dents with a fingernail.

Choose polystyrene for a quick, low-cost lift in a rental or a room you will change soon. Choose polyurethane for bathrooms, long runs of cornice on a tight budget, or where weight is a real concern. Choose plaster where detail, authenticity and longevity matter most, especially in a period home or for a feature piece that people will look at closely.

Every Flare piece is hand-cast in natural plaster to order in Shrewsbury and is ready to paint with ordinary emulsion. See how it takes colour on our paintable plaster page, or browse the Heritage & Classical collection.