Aluminum Restoration

The basic procedure to restore aluminum trim is;
  • Strip off paints
  • Strip off anodizing layer
  • Straightening (remove dents, nicks, bends and reshape part to original shape)
  • Hand polishing to a mirror finish
  • Bright dip
  • Anodizing
It is important to strip off paints prior to removing the remaining anodizing coating. If the paint is not removed ahead of time, it can act as a mask and complicate the removal of the anodizing layer

There are several methods of removing the anodic film protecting the base metal. We prefer to do it chemically using a solution of Sodium Hydroxide (NaOH).
Sodium hydroxide is a harsh chemical, the handling of the chemical and the stripping should be done by a professional.

Aluminum straightening is a delicate operation where the soft metal is being hammered from the back and then filed to get rid of all the imperfections.
Special tools are manufactured from time to time for specific needs.
In most cases, when the aluminum part is not ripped or broken , it can be restored to show quality standards.

Aluminum can be welded and anodized, however, welded aluminum tends to anodize in a different color than the rest of the part (due to temperature and alloy composition).
We weld aluminum as a last resource. We prefer to work with parts where welding is not required. (sometimes it is not possible).
If the area to be welded is not shown (it gets covered with paint, or it is not shown when mounted), then welding on aluminum is not an issue.

Polishing involves a powerful lathe, special wheels, and belts. In order to polish aluminum, the anodizing layer has to be removed (stripped off) first.
It is important to use the right belts, wheels, buffing and coloring compounds and protective equipment.
The polishing lathe spins at very high RPM. accidents could happen is the parts are not hold properly and the operator is distracted.

Bright dipping is also known as chemical polishing. The aluminum parts are dipped in a hot phosphoric acid solution for a few minutes. It is a critical step in the process as the bath has to be properly balanced, otherwise you are bound for disaster.
Many restorers do not have any knowledge of bright dipping and will try to sell you the idea of polishing only without any more processing. BIG MISTAKE!!!
All the OEM parts were anodized to protect them against corrosion and bright dipped to enhance appearance.
Once a part has properly been bright dipped it will present a specular (shiny) appearance and ready to accept the protective anodizing layer.

Anodizing is performed in a sulphuric acid solution. It is an electrolytic process that uses DC current as the driving force. A chemical reaction takes place where the surface exposed to the acid solution transforms from aluminum to aluminum oxide, which is extremely hard and at the same time protects the base metal against corrosion and scratching.
The aluminum oxide film is porous by nature, it is analogous to a metallic sponge, therefore, it is possible to use dyes to color aluminum.
It is not unusual for an aluminum anodized part to last years in service prior to the film being destroyed by the elements.