How To Paint Interior Exterior And Metal Surfaces

Project Overview

How long will it take?

You should be able to paint a 4m x 5m room with one coat in five to six hours. If you apply two coats, allow time for the first coat to dry. For water-based paint allow two hours, and overnight for oil-based paint. Don’t apply oil-based paint after 3pm in cooler climates. You can safely reckon on two or three days to paint a room and clean up afterwards. 

It’s important to remember different surfaces require different paint products, pre-painting treatments and painting techniques.


Always read the instructions, keep tools and materials away from children and wear an approved face mask.
Be sure to wear safety glasses and hand protection all the time. Also, never pour paint or paint waste down the drain.


Hydrochloric acid
Steel wool
Sand paper
Methylated spirits


Paint brushes/Rollers
Wire brush
Paint tray

Step by Step Instructions

1 How to paint exterior surfaces
2 How to paint interior surfaces
3 Preparation and painting of metal surfaces
4 Hints and tips
  • Step 1. How to paint exterior surfaces

    Bricks, masonry and cement render: Can be coated with two coats of water-based acrylic finish without a sealer. required. However, with some bricks, a brown to purple colouring appears on the surface after painting. Check that the brickwork is dry, patch the affected area with an oil-based sealer and repaint the bricks or wall. This should solve the problem.

    Cement tiles: Before repainting, remove moss, mould and lichen. Use a bleach solution (preferably a bio-degradable cleaner) followed by thorough water rinsing and scrubbing or heater jet cleaning. Finally, apply two coats of exterior water-based acrylic topcoat. If the surface is still chalky after this check the manufacturer’s instructions. 

    Concrete driveway/patios: Bare concrete surfaces must be acid etched prior to painting by applying a solution of 1 part hydrochloric acid to 3 parts water. Allow two coats of selected paving paint. Coloured oxide topped concrete may require more than one acid etching to make the surface porous enough for the paint. After concrete has dried apply a little water to test. The water should be rapidly absorbed. If not, repeat the acid etching.

    Note: An etched primer ‘3 in 1’ is available. Bubbling and flaking can be caused by rising moisture which, unless stopped, can mean over coating with normal house paint won’t work.

    Fibreglass sheeting: Corrugated fibreglass and plastic sheeting used on pergolas and shade houses can be painted with an exterior water-based acrylic paint. Sheeting should be scrubbed with a steel wool pad and a mild solution of detergent in water, rinsed off and allowed to dry before painting.

    Cement sheeting: Cover with two coats of exterior water-based acrylic paint. Old unpainted surfaces may require surface cleaning before painting. The use of oil-based sealers is usually not necessary and may lead to further problems.

  • Step 2. How to paint interior surfaces

    Ceramic tiles: Because the paint has nothing to stick to ceramic tiles are hard to paint. Glazed wall tiles can be painted except in wet areas where the moisture will lift the paint. Due to heavy foot traffic, painting glazed floor tiles is not a good idea as paint will easily be removed. Coat unglazed floor tiles with a slate sealer to protect against grease and dirt.

    Craftwood: A form of particleboard, craftwood has a wax content which can interfere with the drying of oil-based paints. Undercoat with a water-based sealer/undercoat and then apply oil-based or water-based finishes. You’ll find Bunnings have specific products for painting craftwood.

    Gyprock: Gyprock is really easy to paint. For a flat finish, two coats of flat plastic paint are usually enough, while for a low sheen or semi-gloss finish, use a coat of water-based sealer followed by two coats of finish. If there is peeling, it will usually be near the cornice and about 75mm into the ceiling itself. This is often due to cornice cement smears not being properly removed before painting. Just scrape it back, apply an oil-base sealer, touch up and re-coat the ceiling.

    Plasterglass: Plasterglass is a smooth white ceiling board whereas Gyprock has a buff-coloured paper facing. The trowelled joints in Plasterglass ceilings can cause paint adhesion problems if the correct sealer is not used.

    Laminex: Before painting Laminex, Formica or other laminated surfaces with tile & laminate paint, de-grease the surface, sand back to a matt surface, then apply two coats. Painting usually works best for cupboard doors rather than bench tops because the enamel is not as hard as the original laminate surface and is less likely to scratch. Bunnings have a range of products for painting tiles and Laminex.

    Peeling ceilings: Firstly, it’s important to fix the cause of the peeling paint (i.e. leaky roof or guttering) otherwise further peeling will happen later. Peeling ceilings should be wet thoroughly with a hot detergent/water solution. Loose areas will normally blister up and can be scraped off. Allow to dry, patch seal bare areas with an oil-based sealer, fill with Polyfilla if needed. Touch up with a top coat and re-coat the ceiling. 

    Texture coatings: Acrylic texture coatings are great for decorative effect or to cover up uneven or cracked surfaces and range from a smooth rippled finish through sand-type finish to a bold rough finish. The finish you get will depend on the type of roller used. Because they produce a thick heavy film, the surface to which they are applied must be sound, otherwise it won’t stick.  Texture coatings are fairly expensive because their spreading rate is only 2 sq. metres or less, plus keep in mind, the coarser the texture, the greater the dirt pick up, especially outside.

    Coolrooms: When painting a coolroom that normally runs down to 4°C, the temperature of the interior surface must be allowed to come up to at least 10°C or the paint won’t dry properly. Any mould or mildew should be treated with chlorine bleach before painting. Water-based acrylic gloss paints can be used and will not taint food. Allow at least 24 hours drying time before returning the coolroom to service.

  • Step 3. Preparation and painting of metal surfaces

    Aluminium: Use turpentine and scrub bare aluminium with abrasive pad then rinse with clean water and dry off. Paint the surface as soon as possible with water-based acrylic paint, or prime with water-based galvanised iron primer if an enamel top coat is to be applied. Anodised aluminium window frames can be cleaned down with water and detergent, and repainted with water-based acrylic finishes.

    Brass: Wipe with methylated spirits to remove any remaining Brasso. Sand and prime with red oxide metal primer and overcoat with 2 coats of suitable oil or acrylic paint.

    Colorbond: Factory-coated for long life, Colorbond is pre-painted galvanised or zincalume steel sheeting. If damaged in transit or during building you should touch it up with a special Colourbond touch up spray pack. For the painting of surfaces next to Colorbond, use Colorbond Trim Colour which is a water-based acrylic matched exactly to the Colorbond colours. When repainting weathered Colorbond, wash down to remove any chalkiness, then apply low sheen exterior paint.

    Copper: Sand back and prime with red oxide metal primer. Polished copper can be treated the same as polished brass.

    Galvanised iron: With a surface layer of zinc to prevent rusting, painting galvanised iron can be hard if the wrong primer or no primer is used. The zinc can attack oil-based paints causing them to flake from the surface, so it’s best to use a water-based acrylic galvanised primer. This can then be top coated with either oil-based or water-based paints. (See also Zincalume and Gutters).

    Gutters: Gutters and downpipes are usually made from zincalume or galvanised steel and can be treated the same way. New gutters should be scrubbed with a steel wool pad and a suitable cleaning agent or detergent, rinsed with water and allowed to dry. Apply one coat of acrylic galvanised primer. If you are within 5km of the sea, apply with two top coats of gloss enamel. Otherwise, either enamel or water-based acrylic is suitable. (See also Zincalume and Galvanised iron).

    Rusty steel: Rusty steel is hard work to treat properly. All the rust should be removed by abrasive blast cleaning or acid pickling. If this cannot be done then scraping, chipping or wire brushing should be used. Apply either a rust remover or a rust converter before applying an oil-based metal primer. The paint coating must avoid as much water, oxygen and salts as possible. The thicker the oil-based coating is, the better. The bare minimum would be a metal primer and two coats of oil-based finish.

    Zincalume: Zincalume is similar to galvanised iron except that the coating is a zinc-aluminium alloy which has a lower corrosion rate, giving it a longer life before rust sets in. Paint the same way that you would paint galvanised iron. (See also Galvanised iron and Gutters).

  • Step 4. Hints and tips

    Top quality paints give you easier and better coverage, are longer lasting and easier to clean than low grade paints. Budget for the best and it will pay off in the long run. 

    For further expert advice, consult the qualified Team Members at your local Bunnings Warehouse.

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