If you have old aluminium windows that you want to either restore the existing colour or you wish to change the colour, then, you can rest easy. You’ve come to the right place.
The process of aluminium window painting can be broken down into a series of steps with two distinct stages. These are preparation and application. The inexperienced however, will try and skip on the preparation to the detriment of the look and durability of the finished product.
The amount of preparation needed mainly depends on the type and condition of the original substrate. For example, if you have old powder coated painted aluminium windows that has chalky paint and rubs off against your fingers, then this will take a lot more preparation than newer powder coated surface that’s not chalking and is being painted for a colour change.
However, anodized aluminium windows will take a lot more preparation than all other substrates regardless of its substrate condition because, the surfaces needs a lot more mechanical abrasion to key the surface up enough to allow the paint to stick.
Protection of adjacent finished surfaces- Whenever you are painting isolated section, it is important that you protect adjacent finished surfaces. When painting the aluminium windows in your home or apartment, you’ll need to think about putting plastic drop sheets down, followed by canvas drop sheets. I suggest applying plastic film and 3M, which you can with a hand dispenser to protect the glass and the walls directly surrounding the window frame.
Cleaning – Make sure all surfaces are clean and free of dirt. Grime and grease are critical in the process of aluminium window painting. If surfaces are dirty then paint adhesion is reduced. Clean the frames on the outside with soapy water and a sponge. However, use a soap that is salt free such as truck wash. Wash off all excess soap with clean fresh water.
Then, alternately clean surfaces down both inside and out with solvent wash such as prepsol.
Use a scour to apply the solvent. The scour will clean and key the surface at the same time. It is important that you carry out a second solvent wash on dirty windows by applying solvent with a clean cloth then wiping off with another clean cloth.
Sanding the substrate – There is no easy way around this process. This can be difficult and monotonous especially getting into the tighter spots such as the upper channel because there is no mechanical sanding equipment that can make the job a lot quicker. Thus, doing the job manually by hand is hard and time consuming.
If you have powder coated surface that is chalking, I would recommend sanding with 120 grit. The sand paper is less likely to clog. If your substrate is powder coated and is not chalking then 240 grit will be enough to key the surface especially if you have scoured it first. However, if your substrate is anodized then you’re in for some real work because you’ll need to break out the 60 grit sand paper. Have some masking tape band aids for the ends of your fingers ready because this is where you are going to be “rubbing your fingers to the bone.”
Sixty grit will really carve the anodized surface up. And you would want the paint to really stick, right? Skip this and you’ll be doing the job all over again. Once you’ve done this, it’s best that you go over the job again with 120 grit sand paper to smooth out the gouges caused by the 60 grit.
You’re nearly ready to start the fun part which is applying the paint. Just before you paint a window give it another clean wipe using your solvent wash, remember to use two different clean cloths.
Painting- Use a three coat system with the first coat being a primer sealer light coat- use a single pac etch primer. The second coat being the first of the top coats, then the second top coat being the third coat.
At this point, you have to make a couple of choices. First, what type of paint do you want to apply? I recommend either oil based enamel or a two pac poly urethane. If you have little or no experience with using two pacs, stick with the oil based enamels and apply it using a quality brush. However, if you have used two pacs before, then, the only way to apply them is by using an HVLP spray gun in order to gain quality finish. The benefit of using a two pac paint over an oil based enamel, is that you will get a more durable quality finish that closely resembles a powder coat finish.