Aluminum is a material that’s widely used for diverse outdoor functions, most notably for roofing, doors, windows, and siding. To sustain its durability and aesthetic, choosing specially-made exterior paint is paramount. Find out what type of paint is best suited for aluminum and how you can achieve the perfect finish. Psst! The secret’s in a meticulously prepped surface.  

The Different Types of Paint for Aluminum

Do you prefer acrylic or glycerophthalic paint? Well, the good news is that both paint types are compatible with aluminum surfaces. However, to ensure the paint in question adheres to the intended smooth surface properly, it’s best to steer your decision-making to glycerophthalic paints.

Naturally, with both the paint types mentioned, there’s a broad range of options. To help you choose the paint that’s best suited for the aluminum surface in question, here are the factors on which you should focus: 

• Adhesion capacity: The better the paint adheres to the intended surface, the more durable it will be.

• Fade resistance: The risk of fading is especially prevalent with outdoor use. As such, choose a paint suited to Canadian weather patterns. 

• Corrosion resistance: For long-lasting aluminum surfaces, protect metal materials from moisture and airborne salt with a layer of paint.

• Flexibility: Aluminum is subject to expansion, therefore, the paint must have expansion capacities. The latter is super important; the paint of your choosing must expand to prevent chipping.  

Can you paint anodized aluminum surfaces? 

Yes, but provided that the surface in question was thoroughly prepped since anodized aluminum prevents the paint from adhering to surfaces. To do so, you have to: 

1. Degrease the aluminum surface

2. Sand the metal

3. Or etch the surface

4. And use a galvanized steel primer 

How to Degrease Aluminum Surfaces

Use a rag soaked in cleaning solvent. It works without oxidizing the material and leaves no traces, deposits, or rings. 

How to Sand Aluminum 

Do so with a number 2 grade steel wool. You can also use a sander fitted with a flap disc. By sanding the aluminum, you’re making tiny grooves into the surface that will later be painted. That way, the primer coat will adhere to the aluminum surface without issue.  

Why etch the aluminum? 

There's one major issue with aluminum surfaces when it comes to applying a coat of paint: it’s too smooth. In other words, it’s extremely difficult to achieve proper paint adhesion, especially if the aluminum is anodized.

To stack the odds in your favour, apply an etching product, such as an etch primer. Etching products are made with phosphoric acid, surfactants, and etching agents. Such products are meant to attack the aluminum surface to render the metal surface rougher, ensuring the primer and paint coat adhere properly.  

Factors to Consider When Choosing Aluminum Paint

Choosing the Right Finish for the Job

The finish isn’t limited to asking yourself whether a second or third coat of paint should be applied. The truth of the matter is that it’s the overall steps combined that ensure a decent result.

For example, to achieve a nice-looking finish, you can apply a primer. By using an aluminum primer, such as a Wash Primer, you’re increasing the paint coat’s adhesion and stacking the odds in your favour, ensuring a flawless finish.

Naturally, to choose the right finish for long-term durability, you first have to choose the right paint, which we already mentioned. 

Colour and Aesthetic

The benefit of paint is that it allows you to coat your aluminum surface in practically any colour of your choosing. As such, when it comes to aluminum-specific paints, you can find the following paint colours: 

• Red

• Yellow

• White

• Matte or glossy black

• Orange

• Purply pink

• Blue

• And more

Courtesy of the broad colour choice, you can either opt for a classic colour, such as white, or for a much bolder shade, such as orange or purply pink. Nonetheless, prior to painting, contact your municipality to make sure you aren’t restricted to urban planning harmonizing rules.  

Paint Durability and Resistance

We covered acrylic and epoxy paint earlier, but note that both are suited to aluminum surfaces, yet epoxy paint has better adhesion.

However, there’s a third type: spray paint. Actually, it’s said type of paint that is typically used to coat all automobile body parts and industrial aluminum pieces. 

Spray paint’s resistance is exceptional, as some of these paints are tested to withstand 200 hours of salt spray testing. It’s a standardized method that allows you to determine the metal’s corrosion resistance. However, such a product is typically limited to professional use. 

Consider Outdoor Environment

Regardless, it’s still important to protect aluminum surfaces, especially if you used the method mentioned above, meaning that of sanding and etching the surface. Note that, as with any metal surface, aluminum is corrosion-prone, which is manifested by all types of microclimates:

• Marine 

• Industrial 

• Urban 

• Rural 

Lastly, why such diverse areas? Because there are multiple root causes of aluminum corrosion, each exacerbating the others: 

• Fresh water 

• Sea water

• Rainwater

• Humidity

• Wind

• Fog

• Temperature

• Chemical products  

The paint that you will apply must form a waterproof coating to protect the aluminum from corroding for as long as possible.

What type of paint is best used on outdoor aluminum surfaces?

The paint choice will determine the service life of the aluminum surface it coats. The more durable your paint is, the longer the metal will be protected from outdoor conditions, such as UV rays, rainfall, or sea air humidity.

As we already mentioned, acrylic and glycerophthalic paints are perfect for coating aluminum, provided that the paint's label clearly states it’s meant for exterior use. 

Which aluminum primer to use?

For aluminum, we advise using a 467 metal conditioner. It’s a solution that should be sprayed directly onto the aluminum surface.

Its composition, made with water-soluble detergent and phosphoric acid, ensures the removal of the following: 

• Grease

• Slight traces of rust

• Oxidation 

Also, 467 metal conditioners are designed to ensure the layers of paint you will then apply better adhere to the surface. In terms of instructions, spray the product onto the aluminum, and wait two minutes before rinsing it all off with water (avoid allowing the product to dry on the surface).

Other primers are also retailed, such as the Behr metal primer. The latter is sold in cans and is applied with a roller with 6-10 mm-long piles or a paintbrush (nylon or polyester) or with an airless paint sprayer. 

How to Paint Over Pre-Painted Aluminum 

Clean the Aluminum Surface

Beware of using just any random product to clean an aluminum surface. Note that sodium- or chloride-based products, which happen to be ingredients found in most household cleaning products, lead to aluminum corroding. 

The best solution remains that of using a primer or a metal conditioner.

Apply an Aluminum-Specific Primer

We already detailed above regarding the use of 467 metal conditioner and the Behr brand metal primer. You can now go ahead and apply a coat of primer using a paint roller or a sprayer.

If you aren’t sure which method to choose between the two, we highly recommend proceeding with the paint roller method. Naturally, doing so is a bit more time-consuming compared to a sprayed-on application, but it results in better coverage.  

How to Make Paint Stick to Aluminum

Prior to painting, no matter the aluminum type, you have to prepare ahead of time. The steps to follow are the same, no matter the type of aluminum you’re painting: 

• Anodized

• Lacquered 

• Powder-coated 

Why is that? Because, at every turn, the aluminum’s protective coating is so smooth that you will have all the trouble in the world getting paint to stick to the intended surface. To make sure it works, proceed with the steps we listed at the beginning of the article: 

• Degrease 

• Sand 

• Etch 

• Apply a primer 

Should outdoor handiwork not be your cup of tea, or if you don’t have the time required to do so, don’t think twice about hiring a painting service. Painting professionals will know how to prevent any problems and offer the best paint formula to face temperature variations and other environmental constraints that may come about from your area of residence. 

Post-Painting Maintenance Tips

Once the aluminum surface has been coated in paint, you can clean it as often as you like, starting with hose down. Water will wash away the build-up of dirt deposited on the aluminum surface.

If that doesn’t suffice, you can proceed with a handwash. Fill a bucket with some lukewarm water, add an all-purpose cleaner, grab a soft-bristled brush, and clean away. 

Make sure to scrub with the aluminum grain, and naturally, start at the top and make your way down so as not to soil the bottom section you cleaned first.

If all your efforts don't pan out, and you aren’t able to remove all traces of mould, keep in mind that these spores are fungi. As such, they're living organisms. To rid your surface of the latter, nothing works better than adding bleach to your water.

However, proceed with caution and keep in mind what we mentioned earlier: sodium- or chloride-based household cleaners corrode aluminum. Before using an all-purpose cleaner, look over the ingredients printed on the label.