Aluminum itself is the desired metal because it is light, strong, and highly resistant to oxidation or rusting that plagues other metals such as steel.
Aluminum when anodized creates a hard, durable coating on the metal that makes it even more resistant to the outside elements.
This means that anodized aluminum will not only resist rust, it will also resist tarnishing and stay in like-new condition if the anodized surface remains intact.
However, over time even an anodized surface will start to wear away and leave the aluminum below exposed.
Cleaning the metal can help offset some of the effects, but it is best to know more about the anodizing process to properly take care of the aluminum.
What is Anodized Aluminum – What are its Benefits?
Put simply, the anodizing process (electrolytic passivation process) is the process to add an extra finish that protects the surface of the aluminum.
It is created by immersing the aluminum into a series of tanks through an electrochemical process.
The result is that an anodic layer comes from the aluminum itself to provide protection.
This provides definite advantages that make it perfect for painting.
1- Additional Corrosion Resistance:
Although the aluminum itself resists the corrosive process anodized aluminum takes it a step further.
By creating a hardened surface, it resists the peels, cracks, and other imperfections that lead to corrosion developing.
With the surface layer intact, the aluminum will stay sound.
2- Better Adhesion for Paint:
For painting the surface, additional adhesion is crucial to keeping the paint intact.
And aluminum when anodized creates the same effect.
This means that the paint will soak into the anodized surface and stick properly, leaving a smooth, clean finish that looks far better than painting aluminum that has not been anodized.
The important thing to remember when painting anodized aluminum is that the surface you intend to paint on should be thoroughly cleaned and dried.
Then you can apply a layer of etching primer followed by 2-3 layers of paint.
You can pick any acrylic or latex paint that is meant to be used on metals.
If painting outdoor items like your aluminum patio furniture, it’s essential to select the paint that is labeled “exterior-grade”.
3- Can Also be Dyed:
If you do not want to paint, you can have the anodized aluminum dyed which is more effective and easier to accomplish.
Standard aluminum cannot be dyed properly, but anodized aluminum can be dyed easily for a faster, more complete coverage.
In addition to the advantages that come from painting, anodized aluminum is simply more durable.
Although the degree of deterioration will mostly depend on the thickness and quality of the anodization, it should last for about 10-20 years.
How to Repair and Polish Scratched Anodized Aluminum?
As beneficial as anodized aluminum is, the material is still subject to scratching which can make the metal underneath vulnerable.
What follows are a few steps you can take to clean and repair the dyed surface which returns the protections that anodized aluminum brings.
Step 1. Wipe the Surface
The first step is to clear away any dirt and loose debris from the surface of the material.
The scratches and imperfections will still be there but using a towel to wipe away the debris will remove the buildup which otherwise will cause issues later.
Step 2. Spray
Once the surface is clean, use a high-pressure rinse to spray the aluminum.
A good pressure washer will clear away debris that did not come off the first time.
A couple of drops of dishwashing liquid mixed into a cup of water and applied with an abrasive sponge can be used to scrub the surface.
Remember that mild dishwashing liquid is enough as harsh cleaners may damage the aluminum and cause it to react badly.
Step 3. Rinse & Dry
Use clean water to rinse away any traces of the dishwashing liquid, then dry with a towel.
If the surface is thoroughly clean, then you are ready for the next step.
If not, then you will need to remove the anodized layer from the aluminum.
To do the stripping, you will need the following items.
- Rubber Gloves & Goggles
- Drain Cleaner: One tablespoon for every gallon of water
The drain cleaner uses sodium hydroxide which will remove the anodized surface.
This allows you to get at the aluminum itself which can now be cleaned.
Mix the solution and dip the aluminum into the pan.
Be sure you are wearing rubber gloves and goggles for protection.
Expose all sides of the aluminum to the mixture. You should not have to scrub as the solution will remove the anodized surface quickly.
If the metal is too large, then use an abrasive sponge and apply the solution to the surface.
Rinse thoroughly with water until all the solution is removed. This should expose the aluminum fully, so it can be properly polished.
Step 4. Sand
Start by using 800-grit sandpaper and rub across the surface until it appears smooth.
You can sand it by hand or use a sander, whichever one you desire.
Just be sure to sand the entire surface.
Step 4. Polish
The next step is buffing.
You will need to use a buffing pad preferably on a buffing machine and move in circular motions across the surface.
Once you have done that, use a soft cloth to wipe down the aluminum.
Inspect the results to see that the entire surface is buffed.
Now, you can apply the polish designed for aluminum or the anodized aluminum surface.
As with the buffing, rub the polish in circular motions across the surface.
And now you have a well stripped and polished anodized or standard aluminum.
For those seeking a solid, durable material, anodized aluminum is some of the best you can find on the market.
In fact, if you are going to use aluminum for a project no matter its size, then anodized aluminum is the way to go.
Anodizing also means you get a proper aluminum surface that will last longer and is far more friendly to painting which only means it will be even more durable.
You will just need to make sure that you keep the polish intact by wiping and spraying the surface often.
Painting over can also add a layer of protection and can keep your items well maintained.
Douglas Becker (aka Painter Doug) has over twenty years of experience as a painter in Adkins, Texas. At present, he resides in Florida with his family.
From painting multi-storeyed houses, condos, and apartments to large commercial buildings and small offices, he had served various customers in areas not only in Adkins but also in Southwest Florida, Sarasota, Naples, and many more. To know more about him check here.