With all aluminum siding painting projects, washing is the most important part. The oxidation that occurs with aluminum siding results in the build up of a chalk like substance on the siding itself which can easily be seen by wiping your hand across the aluminum. This substance, if not removed, will affect how well the paint can adhere to the siding. In order to remove enough of the chalk like substance with a power washer, you would need to get close enough to the siding that you run the risk of damaging it. Therefore, here at Textbook Painting, we have a special cleaning process that we use when painting aluminum siding.
The first step in our hand washing process is to lightly power wash the siding. Once it is wet, we use brushes and a cleaning agent to scrub the siding. The cleaning agent makes the removal of the chalk easier and it also kills any mold, mildew or algae that may be growing on the siding as we don't want that festering beneath our top coat of paint. Following the scrubbing, we will go back over the siding with a light power wash to rinse.
Power washing your house is like taking your car to a car wash and our hand washing process is like washing your car by hand in the driveway. The car wash will certainly clean your car but is nothing compared to washing it by hand. You should not have your aluminum siding painted by anyone who does not understand the importance of properly washing the siding beforehand.