Surface

Treatment

New Bare wood

Look for cracks and blemishes which need filling. Use fine surface filler for interior wood and a waterproof wood stopping or epoxy-based wood filler for exterior timbers. Apply knotting to all visible knots to stop resin bleeding from them. Smooth the wood by hand, using fine abrasive paper, working only with the grain. Alternatively, use a drum sanding tool or a flap wheel in a power tool, again working with the grain. Be gentle because with power tools even the finer grades of abrasive paper remove wood very fast.

Old Bare wood

If there are signs of damp rot – soft patches easily penetrated by a penknife blade. See Wet And Dry Rot. Fill all cracks and gaps with filler as for new wood. When set, smooth with line abrasive paper. Do not leave timber unprotected for any length of time especially if it is outside. As soon as preparatory work is complete, apply a coat of wood primer.

Painted wood

If the paint is sound and in good condition do not strip it unless too many coats are causing an obstruction eg, making windows hard to open, for instance. Clean down the sugar soap and water. This removes dirt and keys the existing paint so that new paint will adhere to it. Keying (roughening a gloss surface very finely), is essential without it new paint is easily damaged and scratched off. Where the paintwork is slightly damaged but is mainly sound, only work on the damaged areas. Rub with a damp flexible sanding pad to remove all loose material wipe clean and allow to dry. Prime bare wood where it is exposed. Then lightly rub the whole area with very fine abrasive paper and wash with sugar soap, as for sound paintwork. Fill small chips and stripped patches with fine surface filler. If these are not filled, a depression will show in the finished paintwork, especially when the paint layers are thick.

Varnished wood

Use a chemical paint stripper or varnish remover to get back to bare wood.

Stained wood

If the wood is to be painted and the stain is old, rub down with a flexible sanding pad. If the wood is to be sealed to give a natural finish, remove the stain wit a wood bleach. Follow instructions on the tin.

Preservative Treated Woods

As long as the preservative is old and dry, paint primer over it. If the coating looks fairly new, unless you know it can be painted, coat the wood with an aluminium primer-sealer. Otherwise the preservative may bleed through.

Surface

Treatment

New Iron And Steel

Wipe off protective grease with lint-free rag, such as a piece of old sheet, dipped in turpentine. Use emery paper to remove rust and wipe clean. Apply metal primer in as thin a coat as possible, or use cold galvanising paint, which acts as a rust inhibitor and primer.

Old Rusted Iron and Steel

Use wire brushes and emery paper to remove all rust. Always wear safety goggles and leather gloves for protection when preparing metalwork in this way.

Fill and serious pitting with an epoxy-based filler. If it is left untreated, rust can eat through thin metal, leaving holes. This quite often happens to old steel window frames. Provide and anchor for the filler by backing holes in a window from with aluminium mesh.

Epoxy based filler is a rust inhibitor, so it can be applied to sound surfaces still showing signes of rust discoloration. Before painting the metal, apply a metal primer, which will prevent further rusting.

Galvanised metal

Steel window frames are usually made in thin sections – only about 2mm thick, and the galvanises surface has a silvery sheen.

Remover dirt and grease with white spirit on lint-free rag. Although a galvanises surface protects steel effectively against rust, it does not afford a good key for paint, and many primers do not grip. Use a zinc chromate primer on a weather surface. On new galvanised steel, use an etching solution followed by zinc chromate.

Clean damaged galvanised areas with turps, then apply galvanising paint to the damaged parts.

Paint chipped Galvanised metal

Clean are areas with turpentine, rub the paint edges lightly with emery cloth to soften them, then treat with zinc chromate primer. Build up coats of gloss to match the existing surface. Often this is a short term repair, if the whole paint film is unstable strip all the paint and reprime.

Aluminium and Anodised Aluminium

These materials do not usually need painting. But if you want to match a colour scheme, clean them with turpentine, dry off and apply enamel paint. No primer or undercoat is necessary. Any whitish corrosion should be cleaned off with a very fine emery paper, followed by cleaning with turps to remover dirt and grease before coating with zinc chromate primer.

Copper

Remove any protective grease with turps and rub away any discoloration with fine emery paper. Wipe clean then apply gloss paint or enamel direct. No primer or undercoat is necessary. Ordinary gloss can withstand the heat of water passing through the pipes.

Stainless Steel

This should not need painting but, if desired apply gloss or enamel paint direct after removing any grease with turpentine.

Chrome Plated Steel

Like stainless steel this should not need painting, but it can be coated with enamel applied to clean surfaces.

Painted metal

As with painted woodwork in good condition, do not interfere with sound paint on metal, unless a build-up is making frames too tight. If the paint does not need stripping, clean it down with sugar soap and water. Key the surface with fine abrasive paper, then apply a primer and gloss paint.

Rust Lifting Paint

Wear safety goggles to protect your eyes. Brush away flaking paint with a wire brush and then scrape back the remaining paint to reveal bright metal. Use an old knife, a scraper or, for stubborn areas, a coarse file. Do not ignore any hidden rust, it can lead to a new attack. Treat with rust inhibitor, apply a metal primer, and then build up gloss paint in thin coats until it is level with existing paint.