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Understanding Anodized Finishes

Panda Windows and Doors has a wide range of color options, including several anodized finishes. But what is an anodized finish and why is it such a great choice for exterior doors?

Anodizing is a process that increases the thickness of the natural oxide layer on the surface of a metal – most commonly aluminum.  It changes the texture of the surface by modifying the crystal structure of the metal near the surface. This process increases resistance to corrosion and damage, thus providing a better surface for paint and adhesives.

Aluminum and aluminum alloys will naturally create a layer of aluminum oxide when exposed to gases containing oxygen, although this layer tends to be fairly thin. To anodize aluminum, the metal is submerged in an electrolytic solution, which is usually an acid. It then acts at the positive electrode (anode). A negative electrode (cathode) is also submerged and then a direct current is passed though the solution. The current then releases hydrogen at the cathode and oxygen to the aluminum, helping it build up a thicker layer of aluminum oxide. Once this is done, the aluminum can be dyed and sealed more effectively and will be significantly more durable.

Anodizing was first used on a large scale in 1923 on seaplane parts to prevent corrosion. It was first performed with chromic acid, but more advanced versions using sulfuric acid became the standard in 1927. Anodized aluminum extrusions, like Panda’s, became popular as building materials in the 1960s and 1970s and although plastic has slowly been replacing this aluminum as a cheaper option, we continue to use it. Recycled aluminum is not only stronger, it’s also more sustainable!

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Keyword: Architecture, Custom Windows, Custom Doors, Folding Doors, Bi-part Doors, Lift and Slide Doors, Glass Walls, Pivot Doors, French Doors, Hurricane Rated Doors, Re-model, Renovation, Commercial, Residential

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