HOW TO PREPARE EXTERIOR SURFACES BEFORE DECORATING
Filling and Patching
Rotten or decaying timber should be removed and replaced. Holes and cracks
should be filled with a good quality filler such as Selleys PlastiBond. Apply filler
with a putty knife, overfill to compensate for shrinkage during setting. Where
movement is likely to occur, use an exterior flexible filler such as Selleys No
More Gaps Exterior.
Masonry and Brick
Scrape away any loose paint and fill holes using an exterior masonry filler, such
as Selleys Spakfilla Exterior, using a broad-bladed knife or scraper. Use a brush
or a rag to roughen the filler before it is completely dry to match the texture
of the surrounding surface. Larger holes may require a ready mixed filler such
as Polyfilla Ready to use Large Cracks.
If you have a lot of sanding to do, consider using a mechanical sander. On paint
work and wood, a general purpose sandpaper can be used. On bare metal a cloth
backed emery paper will last longer and do the job faster.
Timber, which has been exposed to the elements for more than four weeks,
should be sanded back to a fresh, new surface. A grey or weathered surface
makes an unsound base and will encourage peeling and flaking. Sand the surface
to remove all greyed timber. Punch any nails well below the surface, spot prime
and fill the nail holes with an exterior timber filler, such as Selleys Plasti-Bond.
Sand smooth and apply Dulux 1 Step Acrylic Primer Sealer Undercoat to
maximise paint durability.
Nail Head Staining
Replace old steel nails with galvanised nails wherever possible. Hammer nails to
~3mm below the surface, fill the holes with an exterior timber filler, and spot
prime filled areas with Dulux 1 Step Acrylic Primer Sealer Undercoat. Sand
smooth and prepare the rest of the surface for painting.
Some common building timbers contain natural staining material called tannin.
These can be dissolved and carried to the surface by moisture on the wood. If
you are using bare timber of this sort with lighter paint colours, which will show
the tannin staining, prime the surface with Dulux 1 Step Oil Based Primer Sealer
Bare Masonry, Bricks and Cement Sheeting
Remove all loose material with a stiff brush. If surface remains powdery or
porous, priming is recommended to improve adhesion and durability. Use Dulux 1
Step Acrylic Primer Sealer Undercoat, and Dulux Prepcoat Sealer Binder on
Cement render, concrete bricks and mortar must be allowed to cure for a
minimum of four weeks, and concrete for a minimum of 8 weeks, before painting
with an acrylic paint. Much longer curing times are required if you plan to use oil
Ferrous metals (those that rust e.g wrought iron and steel) – make sure the
surface is clean and free of rust. Remove rust by sanding or wire brushing and
treating with Dulux QuitRust Rust Remover. Then apply Dulux Quit Rust All
Non-ferrous metals (those that do not rust e.g. galvanised iron and Zincalume®)
– Never apply oil based enamel paints direct to galvanised iron or Zincalume®.
Prime with Dulux Quit Rust All Metal Primer first. Aluminium, copper, brass and
stainless steel – Never apply paint directly to these metals as the paint will not
stick. Ensure the surface is clean and free of rust by scrubbing with a scouring
pad and water, then wipe down with a clean rag. Apply Dulux Quit Rust Etch
Primer before applying the top coat.
New Plastic Down Pipes and Spouting
Wipe down with a cloth dampened with turps before lightly sanding to provide a
sound key for the paint to adhere to. Wipe again with a water dampened rag
Previously Painted Surfaces
Test the paint in several areas by cutting with a sharp knife and pressing 10 cm
or so of adhesive tape firmly across the middle of the cut. Rip the tape away
quickly – if any pieces of paint come with it, you will need to strip the loose paint. Stripping
If the paint needs to be stripped back, the most common method is to use a
heat gun or a chemical stripper such as Selleys Kwik Strip. For small areas, a
manual or drill mounted wire brush or dry scraper may be adequate.
Sound Paint Work
If the paintwork is in good condition, a light but thorough sand should be
sufficient. Any small areas of peeling or cracking may be sanded back. Holes or
defects should be filled and spot primed. Painted brick or masonry should be
washed with a high-pressure cleaner and a stiff bristled brush.
Blistering Flaking and Peeling
On wooden surfaces, this is usually caused by moisture trapped beneath the
paint. It happens most frequently on the north and west sides, as these areas
receive the most heat from sunlight and is more common with dark colours that
have been applied over old paint. The first thing to do is remove the source of
the moisture. Around windows and doors, look for cracks and seal them. In the
walls the problem may be condensation, so the installation of additional vents
may be required. Strip as much as practicable, sand smooth and prepare using
Dulux 1 Step Acrylic Primer Sealer Undercoat.
Chalking on timber
Over time Oil based enamel breaks down in our high UV sunlight to create a
chalky or powdery surface. This should be scrubbed off and the adhesion of the
old paint tested before repainting.
Remove surface mould growth by using a household bleach (hypochlorite)
solution prepared by mixing one part bleach with three parts of water. Wear
gloves and goggles to protect you from splashes, and apply with a thick scouring
pad, rubbing to remove the mould. Leave the solution on the surface for 15
minutes then wash down with clean water. This process may need to be repeated to
fully remove mould growth.
(via the Dulux Website www.dulux.com.au)