Using a Primer for Outdoor Painting.

In Singapore the exterior of your home takes a beating. With the extremely hot sun and sudden downpours, its your paint takes the brunt of the damage. Now if you want to give your home a longer lasting exterior makeover, then you need to make sure its done right. 

When doing outdoor painting, preparation is the key to a good paint job. Surface preparation is the only way to achieve a perfect finish. Different preparation and different types of primers will be needed depending on the surface and its condition. There are two main types of primer: oil-based latex or water-based. Oil-based primers normal take longer to dry but are more durable. Below are a few common types of surface that need priming before painting and the different methods of preparation you will need to follow before priming. 

New, weathered or untreated wood 

Use a latex-based primer on new, weathered or untreated wood. Always make sure that the wood is fully dry before priming. Always give the wood a sand and thorough clean before the priming starts, by doing this you will ensure that you achieve a smooth and professional finish. It is recommended to use an oil-based exterior wood primer for blocking tannin, water, and other stains. 

Previously painted or treated wood 

Before you start to prime, remove all the loose or flaking paint. Sand the rough edges and uneven surface. This is important to get a smooth and professional finish. Any areas that are bare should be sanded and dusted off to give the primer a dust free surface to adhere to. Old paint can be chalky, so an oil-based primer should be used. If the old paint has not flaked and is still adhering well to the wood, you do not have to use a primer. You can simple sand, clean and paint. Treat treated wood the same way, sand, clean and prime. Remember when using paint or primer on painted or treated wood, do a test on a small area to make sure that there is no reaction to the old paint or treatment. 

Stucco and masonry surfaces 

 Masonry tends to be porous so use a latex sealer or primer. Remove all loose, peeling paint and power wash to remove any chalk. Remove dirt and grease with a product such as a degreaser and cleaner. Remove mildew stains with a mildew stain removing product. Cracks and gaps wider than 1.5 mm should be routed open, dusted and patched. Use an acrylic caulk around windows, doors and trim. You only need to use a primer where old paint has been removed by sanding or any other surface preparation. 

Aluminium and galvanised iron surfaces

Only use metal primers on metal and aluminium. Always read the instructions on the tin to ensure you have the correct primer for the surface you are priming. Clean the surface using a non-metallic scouring pad or steel wool. Use a non-alkaline cleanser on a rag to thoroughly clean the surface before priming. The key to painting metal surfaces is to prevent rust form reforming. It’s important to remove any rust before applying a latex or oil-based primer that inhibits rust. Two coats is best to prevent future rusting. If the surface has been painted before, sand the surface to get a smooth finish. It is advisable to use a primer even if the surface has been painted before, this will ensure that the paint sticks to the surface and there is no chance of the paint reacting to the old paint. 

So in short you need to ensure that the surface you are priming is always smooth and clean, this is for all surfaces. Dust or oily residue can cause the primer to react and you will need to start all over again. Always read the instructions on the tin and use the correct primer for the surface you are intending to primer. Do this and you should always get a good result.

Planning to do a external painting job and want a professional to do it?

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