Painting Aluminum Siding
By Matt Weber
When the old paint wears away, it’s time to wash away the chalk and apply a new acrylic latex.
The house I’ve been remodeling was built in 1978, and the exterior paint colors did nothing to hide its age. The aluminum siding was a shade of beige that had aged into a dull mustard tone, and the trim was a rust-colored reddish brown. The homeowners hated the look, but the metal was still in decent shape, and they didn’t want the expense of re-siding the entire house. A new paint job was the solution. However, over time the original paint coat of the siding had developed a chalky film, caused by the old paint film wearing away. The chalk had to be removed before slapping on a new coat. We had a lot of prepping and painting ahead of us. Here’s how it went.
On any sort of painting project, surface preparation is absolutely critical for any hope of success. Obviously, you need to remove any loose dirt or debris. There was also a lot of shrubbery to cut and remove for unhindered access to the house walls. The chalk that coated the old aluminum siding posed the biggest obstacle for this project. If you wiped your hand across it, you’d draw back a dirty, yellow palm. This stuff seemed to cover every square inch of siding and made for a lousy painting surface.
To remove it, I turned to my trusty pressure washer, a heavy-duty Maxus unit that was equipped with a detergent tank. First, I washed down each wall with a garden hose to remove the loose dust, and then filled the detergent tank with Krud Kutter Pressure Washer Concentrate specified for house siding. When applying a detergent with a pressure washer you have to lower the pressure and use the right nozzle—a low-pressure tip. This means you won’t have the power to throw the detergent as far and as high as with a high-pressure setting, so if there’s more than one level to your house then you’ll need a ladder. I sprayed on the detergent over the entire wall of the house, working from the top downward, and allowed the chemicals to agitate the surface for a few minutes, per the Krud Kutter instructions. Before spraying it off, I could already see the murky chalk substance dripping down the walls with the detergent.
To clean it off, I switched nozzles and returned the washer back to a high-pressure setting. When washing metal siding, it’s best to get the nozzle as close to the siding as possible, which makes the most use of the powerful water stream. I worked my way down the ladder, blasting away the detergent and chalk, cleaning one wall at a time. Sheets of chalky water streamed off the house like dirty milk.
During this phase of prep work I had the opportunity to test a new pressure-washer nozzle from Hyde Tools (www.hydetools.com). It featured a pivoting nozzle specifically designed to save time and effort. You can complete jobs faster, work more safely and more easily by aiming the stream directly at the work surface without overreaching—very nice when you’re on a ladder. Just twist the grip, and the head of the wand pivots 90 degrees up and down, so there is no need to stoop, bend or kneel to get to hard-to-reach places. The nozzle also twists to enable side-to-side work. The Pivot Nozzle is ideal for overhead work. In my case, pointing the nozzle straight up to spray the house soffits would have resulted in all the water cascading back down on top of me. By pivoting the nozzle, I could stand to the side, spray upward and avoid the ensuing waterfall.
Even after all the pressure-washing, there were still traces of chalk that I hit with some detergent and a soft-bristled carwash brush on an extension handle. The chalk was stubborn. To ensure longevity of the new coat we made sure to choose a high-quality acrylic latex paint that would withstand the weather and cling to the metal surface despite any leftover traces of chalk. We went with the new Valspar Duramax paint, available at Lowe’s (www.lowes.com), which features long-lasting cross-linking technology and comes with a lifetime warranty. The Duramax brand also has primer mixed right in with the paint. And, because of the chalk problem, we took a belt-and-suspenders approach to paint adhesion by blending the paint with a product called EmulsaBond from Flood Paint Solutions. EmulsaBond is specifically formulated to help exterior latex paint stick to hard-to-coat surfaces.
When choosing paint color, it always helps to see a sample applied to the project. We slapped a couple of colors onto the siding, and quickly decided that green was not the way to go. We chose a grayish beige called “stone manor,” specifying a satin finish for the metal siding, and white with a gloss finish for the trim.