Mill finish refers to raw aluminum that has no finish applied to it. Typically, Mill Finish has a shiny or “mirror-like” appearance with some visible manufacturing lines. Mill finish is the finish of choice for installers who are going to prime and paint the material in the field. Prior to priming and paint application, mill finish trims must be cleaned and allowed to dry. Most residue or surface impurities on the trim can be removed with regular dish soap and water or vinegar. Since the material is raw it does not have any protective coat on it and should never be left exposed for an extended period of time or the metal may begin to oxidize.
Anodizing is one of the most common finish choices for extruded aluminum. It is a multi-step electrochemical process in which the aluminum is dipped into a variety of different “baths” producing a hard and corrosion resistant skin to the metal. The aluminum is attached to racks and dipped into various acidic baths. The first step is the cleaning process in which the material is dipped into an acidic bath where any surface impurities are removed. After the cleaning process the aluminum is then immersed into a vat containing an electrolyte. An electric current is passed through the tank causing the aluminum to oxidize until the desired level of thickness of the material is achieved. For the final process the aluminum is dipped into a chemical bath to seal the exposed pores and ensure the material has a corrosion resistant surface.
Anodizing can create a variety of different colors for the aluminum. The most common color is “silver” or a “satin gray” also known as a clear anodized finish in the industry. Coloranodizing is achieved by submerging the material into a dye. Flannery offers seven different variations of color anodizing as shown to the right. The intensity of the color is based on the length of time the material is submerged. Color anodizing is not an exact science and there are many factors that can cause variations in the color, therefore you may not achieve the same shade each time the material is dipped into the dye. To help ensure the aluminum has a similar shade it is best to order your material all at one time.
Flannery’s aluminum trims can be paint matched with virtually any color of your choosing. We use a Kynar® resin based 2-coat baked on factory paint that is highly resistant to external forces. Painted finishes are recommended if the trim is going to be used on exteriors exposed to harsh environments. Proper pretreatment of the material must be performed in order for the paint to adhere evenly. Our painter will clean the material to prepare it for the priming process. Flannery’s trims go through a chem-film process prior to primer and paint application. After sufficient cleaning and drying has occurred the aluminum is sprayed with the paint and then baked in an oven to harden the paint.
Flannery also offers powder coating when specified. In powder coating the paint is applied to the aluminum in powder form and then baked causing the powder to permeate together and create a smooth flow of color. It is typically more resilient than traditional liquid paint. A proper cleaning process before the powder coating application is essential and ensures the coating will stick to the material. Flannery’s trims go through a chem-film cleaning process prior to primer and paint application.
Chemical conversion coating (chem-Film), also known as Alodine, is a multistep process where the aluminum receives a protective chemical coating. The material is first cleaned and then a chromate is applied to the metal substrate forming a protective layer on the material until primer and paint can be applied. Chem Film is used entirely for protective purposes and not as a decorative coating, so it is typically not necessary on all jobs. Chem-film is best when the aluminum will not be installed immediately and will sit on a job-site for an extended length of time (i.e. months). The chem-film process is primarily done in a factory for factory painting preparation. Chem Film is also used for Fiber Cement trims in order to protect the aluminum from the corrosive properties of the Fiber Cement Paneling.
If you have any questions regarding our finishes or any other matter please feel free to contact us via email or call 818-837-7585.