Aluminum siding is not affected by water and it does not rust. However, when aluminum comes in contact with air, it forms oxides. As a result, with the passage of time, the color of the siding fades out and it loses its sheen. Then the signs of wear and tear show up on its surface and it looks really ugly. For this reason, aluminum sidings require regular maintenance. Now, replacing an old siding with new one will prove to be quite an expensive affair. So, the suitable alternative is to add a fresh coat of paint on it. Latex paint has ammonia content that reacts with the oxide of aluminum and leads to the formation of a gas that creates bubbles below the paint coat. As a result, the paint cannot bond well with the aluminum surface and gets eroded easily. Therefore, you should choose an acrylic latex paint for siding. Any low luster or satin finish paint also works wonders on it. Once you have finalized the type and color of the paint, follow the steps that are given below: Preparing the Siding You have to first clean up the entire siding thoroughly. People often tend to commit the mistake of avoiding this step, as it is quite a tedious job. However you cannot afford to skip it because on a clean and well-prepared surface, the applied coat of paint bond really well with the underlying aluminum. Inspect the siding carefully to find out the spots with deteriorating paint, corroded surface and mildew growth as these areas need special attention during cleaning. Scrub the siding with a piece of sponge or brush dipped in soapy water. Then, rinse it off by pouring water from the top of the siding, downwards. Clean it up properly so that the residues of soap and the pigment that are stuck on the siding are washed off completely. If required, you can wash the siding using a pressure washer. Keep the siding untouched for the next few days and let it dry up. Application of Primer Primer has to be applied on the siding to obtain a better paint finish. It will also help the paint to last for a longer duration. An oil-based metal primer is the best choice for aluminum. You have to select one such primer whose color has close resemblance to the color of the paint that you are going to apply later. Now, mix the primer with a paint thinner in the proportion of one quart of thinner to one gallon of primer. Start applying the primer using a brush or an airless sprayer. In case the old paint on the siding was latex acrylic, you need not apply any primer and you can skip this step. Application of Paint Aluminum siding should not be painted on a windy day. Moreover, you should not carry out the task under direct sunlight. This is because, heat and wind tend to decrease the longevity of the applied paint. A cool and cloudy day is ideal for painting the siding. Just make sure that the time gap between the application of primer and the paint is not more than 48 hours. Sand the freshly applied primer coat with a 150 grit sandpaper. A light sanding facilitates better adhesion of the paint. Then, use an airless sprayer for paint application as it will help you to obtain an even finish. A foam roller is good and can be used for this purpose. However, in that case, you may have to apply a number of coats. Give an ample amount of time to the paint to dry up. People prefer to paint their old siding mainly because it is less expensive as compared to installing a new siding. If you follow the instructions given here properly, then you do not need to engage the services of any painting contractors to carry out the job. Thus, you can give an attractive, new look to the siding without shelling out a lot of money.