What Are The Characteristics Of Anodized Aluminum?
In order to reverse a process, we first need to know at least the basics of how the process materializes. The aluminum surface of a component is placed in an electrolytic chemical bath with electric current running through it to induce the process of aluminum oxidation. This process artificially changes the structure of aluminum oxide on the surface of the metal, providing a surface finish that is more durable, stain-resistant, and corrosion-resistant.
Bare aluminum is put through this process for many reasons. Some are purely aesthetic, such as giving a shiny finish, but others have an applied purpose. Anodized aluminum doesn’t chip or stain, and if it’s achieved with a hard anodize solution, it can provide unbreakable parts for larger objects. An anodized finish on aluminum can be achieved using different types of solutions, and it usually serves a unique purpose. The anodic film that coats the aluminum can also provide electrical or thermal insulation traits.
Removing Anodized Aluminum Coating At Home
In order to remove the anodic film, you may have heard you need to use various chemicals or a particular stripping solution. That is, for the most part, true. You can also try to remove the coating with some common household cleaning products. However, we can’t guarantee the efficacy of those, as results may vary.
What’s more, plenty of other aspects will determine the results of one such home experiment. You may need to use the product more than once, or you may end up with a patchy aluminum component. There’s the possibility that you’ve taken it out of the solution too early, and the coating hasn’t had a chance to dissolve properly. Some home experiments have caused objects to completely disappear, dissolving in a strong solution that the owner chose.
Why are we telling you all this? While we are able to give you some guidelines, we can’t know specifically what you need to de-anodize, and every little detail and circumstance matters.
Removing Anodizing From Aluminum
If you’ve consulted some bike forums or other forum posts on removing anodized coating, you’ve surely come across our top pick on the anodized aluminum remover list. Half of the entries on our list are actually found among common household cleaning solutions, such as drain cleaners or oven cleaners. But like we said, simply immersing them or spraying solutions on aluminum components doesn’t always do the trick. It’s very important that you do this in a controlled environment, but we will touch on safety precautions later.
- Sodium Hydroxide: Also known as caustic soda or lye (NaOH), it is the most common method for stripping anodized coating. The concentration of caustic soda is generally 2-10% of 50% liquid caustic soda by volume in water. Depending on the bath concentration and temperature, the anodic coating should strip in a few seconds to a few minutes.
- Potassium Hydroxide: Also known as caustic potash (KOH), this solution acts as a strong base (alkali) and reacts well with acids. It’s commonly found in drain cleaners, along with sodium hydroxide and sulfuric acid. It’s likely that, when applied together, this caustic etch solution will result in a matte appearance on the component.
- Acid Etching: This process involves a mixture of chromic acid (CrO3) and phosphoric acid (H3PO4). The end result will probably look the way it did before the aluminum was anodized, as this chromic phosphoric acid solution is proven to not affect the aluminum surfaces or cause further pitting.
- Deoxidizing: To strip the aluminum surface, you can also use a strong de-oxidizer. The aluminum anodized coating is actually a thick oxide layer, and to de-anodize would mean to get rid of this top layer of finishing. Here’s one way to remove the anodic finish from a knife. It also serves as a good guide on how to remove anodized color from aluminum.
How to Remove Anodized Aluminum Finish By Hand
We are about to debunk some myths on how to remove anodizing on aluminum surfaces. The surface treatment can be easily removed with the proper equipment and safety precautions. To adequately strip anodized or powder coating, you’ll need some chemicals, but you still might have to use some old-fashioned elbow grease. This means that even though chemicals do their part, you’ll need to manually grind or sand the surface using fine-grit sandpaper. If you need the component to shine after sanding off the imperfections, then you should learn more about polishing and how it’s done. But prior to starting any kind of project, make sure that you’re in an environment where your surroundings won’t get damaged, and you should only handle the chemicals if you are wearing thick rubber gloves.
Conclusion
As we said, you can search forum sites for more advice on how to remove anodizing from aluminum parts, but we have tried to assemble the basics of this process in one coherent blog post. The bottom line here is – you can use oven cleaner to strip the anodize layer, or you can make do with drain cleaner to remove anodizing from aluminum. Either way, you should find out as much as you can, consult a chemist, and make sure to wear protective gear while undertaking this DIY project.
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