A quick guide to painting aluminium

Aluminium is an extremely versatile material that has a range of different applications. It is used for everything from doors to cans, and the material is used extensively in the aviation industry, and even the world of space travel.

In the case of us mere earthlings, aluminium is used extensively all around the house. Your garage door is probably made from aluminium and you might have a tin roof if you’re living in an older property.

While aluminium can be painted to suit other decorative elements, there is a very specific process that needs to be followed when you want to give aluminium a new look. Here are the steps you’ll need to follow before and during the process of painting aluminium.

1. Prepare the area

Because aluminium is not a porous material, pre-painting preparation is indispensible if you want your paint job to last and not crack or peel after a few years.

Bare aluminium needs to be cleaned and degreased by adding a few drops of degreasing cleaner – dishwashing soap is a good alternative if you can’t find a degreasing cleaner – to a bucket of warm water. Use a rag to wipe down the surface of the aluminium with the water-and-degreaser solution, then rinse with clean water and dry with a clean cloth. Make sure to pay particular attention to rusted spots that might prevent the paint from properly adhering to the surface you are painting. Do this by scrubbing away rust with a wire brush when you are cleaning it. If you are repainting the surface, you can skip this step, as the chemicals in the process of removing the old paint will clean the surface thoroughly enough.

The next step is to sand the surface area so that the primer has something to stick to. Safety goggles, work gloves and a dust mask should always be worn during this step of the process. First sand the surface with coarse-grit sandpaper (80 to 100-grit) then follow with finer-grit sandpaper (300 to 400-grit). Rinse again with warm water and degreaser, and dry the surface.

Prime the surface

A self-etching primer that can be found in most hardware stores needs to be applied to the aluminium before it is painted in the colour of your choice. Skipping this step is likely to lead to chipping and peeling. In a well-ventilated area and while wearing a respirator mask, goggles and gloves, evenly spray one light layer of self-etching primer onto the aluminium, holding the can about 20cm from the surface. Check the primer can to find out what drying time between coats the manufacturer recommends, and let the area dry before applying another even coat of primer. Repeat this process until you have applied three to four coats of primer, then let the primer dry and cure for at least an hour. The curing process should not be left out, as this will ensure that the primer and paint do not peel. After curing, check the surface for any imperfections and sand these away with fine-grit sandpaper.

Painting the aluminium

Technically, you can use almost any paint on the aluminium once you’ve primed the surface area, but paints with a matte finish are preferred over glossy alternatives. This is because glossy paint shows any imperfections in the metal more clearly than matte paint. Take the conditions that the aluminium you are painting will be exposed to into account, and choose paint accordingly – for a garage door or roof, exterior paint that can weather the elements needs to be used, for instance.

Apply one thin layer of paint in straight, overlapping strokes that go in the same direction. Check the paint bucket for a suggested drying time between coats, and let the first coat of paint dry until it is dry to the touch, usually between 5 and 15 minutes. Repeat this process until you have applied at least two or three coats of paint. Let the paint dry and cure for 24 to 72 hours.

After the paint is completely dry and cured, apply a few coats of spray-on or brush enamel, taking care to let the enamel dry to the touch before applying another layer. Let the enamel dry and cure completely for between 24 and 72 hours, to ensure that it does not become tacky.

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