Elaborate ceiling cornices and moulded details are all too often caked in layers of distemper and old paint that have built up over years, obscuring the fine details. Once a very popular finish, distemper is powdered chalk or whiting mixed with a glue size. The problem occurs when you try to paint over it, as when it is wet it re-dissolves and comes away with the newly painted surface.
If cornices and mouldings have been treated with distemper you will need to apply a stabilizing primer to bind the surface. Alternatively, because it is water-based, distemper can be removed – if you have the time, energy and a cornice worthy of display. Wet an area thoroughly and scrub it with an old toothbrush until the moulded detail becomes clear, then, using a pointed stick – a wooden barbecue skewer is ideal – scrape away the distemper from the details. Once removed, stabilize the cornice with primer. Other paint covers can be removed by scrubbing gently with a stiff bristled brush and wiping the surface with white spirit. Thick build-up of paint is best removed using a paste stripper.
There are several types of coving: builders’ merchants sell one made of gypsum plaster and they also supply the special adhesive required to fix it. Other covings are made of polyurethane, polystyrene and fibrous plaster. Polyurethane and polystyrene coving is best cut with a sharp blade, while fibrous plaster is cut with a fine-toothed saw. Always cut from the face side. Cut ends of fibrous plaster should be lightly sanded with fine glasspaper, but polystyrene and polyurethane coving cannot be sanded, so make sure your cuts are clean and accurate. You can buy specially prepared corner pieces if you don’t want to cut your own mitred corners. Plaster coving can be painted, while polystyrene and polyurethane can be left unpainted. If you do decide to paint these, use emulsion paint as gloss paints will create a serious fire hazard. Before fitting coving, wall and ceiling paper and paint should be stripped off to reveal bare plaster. Adhesive is applied to the back of coving; with plaster coving, the wall and ceiling must also be dampened with water.
Stripping Moulding Details
Stripping moulded details can be done ‘dry’ using a scraper or sharp blade, but take care not to scratch or damage the surface beneath. Chemical strippers in gel or paste form are ideal for removing layers of paint that are obscuring details. Follow the manufacturer’s instructions regarding application carefully.
Scrape off With Fine Wire Wool
Fine grade wire wool is the best tool for removing the strippers and old paint without damaging the surface. When the ball of wire wool becomes clogged with debris, replace it with a new piece.