How to Polish Scratched Anodized Aluminum?

How to Polish Scratched Anodized Aluminum

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?

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 and polishing.

A few reasons why anodized aluminum is often used over non-anodized versions include:

1- Better paint adhesion

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”.

2- 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.

3- 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.


Repairing 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 fix scratches on the surface which returns the protections that anodized aluminum brings.

Step 1. Clean the surface

The first step in removing scratches from anodized aluminum 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.

Once the surface is clean, use a high-pressure rinse to spray the aluminum with water.

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.

If you want you can use a bit of homemade cleaner like baking soda, which can also do a trick.

Step 2. 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 3. Sand & polish the aluminum

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.

Once you are done with sanding, 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.


How to De-Anodize Aluminum Surface?

There can be instances when you do not like the anodized finish on your vintage aluminum canisters or window frames.

Another reason you may want to get rid of the anodized finish is that it’s tarnished, weathered, or outdated.

Fortunately, there are ways to remove this finish without the need of buying and using expensive products.

Drain cleaner is one good cleaning agent that can help you get the job done.

A typical drain cleaner will contain sodium hydroxide which is a powerful chemical that can efficiently remove the aluminum’s outer coating simply by deoxidizing it.

  • Start by putting your rubber gloves on for protection
  • Fill a large bucket with a water and add a tablespoon of drain cleaner for every gallon of water
  • Now put your aluminum pieces into this solution for 5-6 minutes
  • Finally remove the pieces, rinse with clean water and allow them to air dry outside

Are Anodizing Touch-Up Pen & Kits Any Good?

For fixing light scratches and repairing damaged black anodize on aluminum there are a variety of products like touch-up pens and kits available on the market.

These products require no heating and expel out no toxic fumes while repairing the scratches on the metal parts. Plus, it won’t chip or rub off like traditional paint.

I would say, it’s much better than using a black marker – if you are trying to fix the issue that way.

With that said, it’s good to know that some of these kits may contain solutions and chemical ingredients that may be toxic in nature and can cause issues, especially if you are trying them on your anodized cookware.

If you really want to use them for metal finish restoration, I should say that I really doubt their efficacy over professional repairing.

I haven’t used them before and have also heard about the negative reviews these products have all over the internet.

So, I recommend that you should try them first only on an inconspicuous area where the scratches are minor.

Other Related Questions

Can you use vinegar to clean aluminum?

Vinegar is an effective powerful ingredient that can help you clean aluminum without scratching.

You can use it to clean dirt, stains, and grime from small pieces of aluminum such as tarnished pots, pans, or cookware.

  • In a bucket, add warm water and white vinegar in a ratio 2:1
  • Soak the tarnished aluminum pieces in this vinegar mixture for about 30 minutes
  • Take them out, rinse with clean water and let them dry completely

Not only smaller pieces, but you can use this remedy for restoring anodized aluminum shower door, trims, window frames, chalky aluminum siding, aluminum rims of your car wheel, etc.

Can you refurbish anodized aluminum using paint?

If you want to give your anodized aluminum metal a new look without using harsh chemicals, painting can be one great way.

  • Start by rubbing and cleaning the surface
  • Wipe down the surface with a damp cloth and let dry
  • Cover any areas you don’t want to be painted with masking tape
  • Apply etching primer and paint on the anodized aluminum using a paintbrush
  • Wait several hours for primer paint to fully dry and then apply a second coat if you desire getting a deeper or darker color

Note: Paints for aluminum can be toxic in nature so do not use them to paint your anodized aluminum cookware or other pots that will touch the food items.

Why am I getting a haze effect when polishing aluminum?

When polishing aluminum you may sometimes notice black stuff or a haze effect that looks weird.

This is caused due to the residue deposits of the metal you are cleaning and polishing.

The more you polish the more it produces the residue so, the effect may not stop ever.

The best strategy to get rid of this black residue is to wipe off the excess polish with a paper towel once you have done with the finish the way you like.

Final Thoughts

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.

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