The aged aluminum process is inspired by tin-type photographs popular in the 1800s. This modern variation uses standard mill-finished aluminum plates which are ‘aged’ by the application of patina. The first step is to remove any trace of the oily film used to protect the plate during its manufacture. This is accomplished using a harsh abrasive cleaner that not only removes every trace of oil, but also roughens the surface of the metal enough to allow a stronger reaction with the chemicals used to stain the surface.
There are a large variety of ways to apply a patina to the cleaned aluminum plates. They can be put in a cold soak, hot soak, or even in a dishwasher. Likewise a large variety of chemicals can be used, including harsh laundry and dish detergents as well as deck and siding cleaners. An additional factor that produces changes in the resulting patina is how the plates are stacked or positioned for this process While the resulting patina is random, the variations described above effect the nature of patterns and the color of the patina which can range from brown or gray to muted rainbow tones.
After the application of the patina, every trace of the chemicals used must be thoroughly cleaned off. Then the plates are ready to be matched with awaiting images printed on transparent film. Laying the transparency on the prepared aluminum plates gives an idea of the finished piece, but one critical step remains before an image and plate are completely matched and ready for transfer.
Often the raw patina on the plate is strong enough to completely obscure the image being transferred. To remedy this, buffing and burnishing the aluminum with scotch bright pads or steel wool reduces the strength of the patina to give the proper balance between the patina in the background and the image in the foreground. Once this balance has been achieved, there is one last cleaning step to prepare the plate for the emulsion image transfer.