Know your finishing options for the lasting results you want.
Raw metal surfaces offer various visual appearances and textures, not all of them desirable. When exposed to the elements, even dry air, most metals change in appearance. If the air is very humid and surfaces are exposed to moisture, some metals will corrode, especially the ferrous metals like Iron and steel. Copper, bronze, aluminum and other metals all react differently to the elements. Surface finishing can be either a required treatment or a desired quality feature to apply to your architectural metal surfaces.
Technically speaking, there are over 100 different kinds of metal surface finishing treatments, so you need to know at least the most common types and how to apply them to your project. You first need to determine what your surface treatments will be used for. Following are the most common applications:
- Corrosion Protection
- Surface Priming for Coating or Paint
Other applications include deburring and smoothing over sharp edges. Whatever end result you’re after, make sure to work with a highly professional fabricator or metals consultant to choose the right technique for the job. The wrong surface finish can either look aesthetically off, much to the disappointment of the designer, or fail to protect the metal resulting in accelerated corrosion and potential structural issues in the future.
Information to help you choose the appropriate surface finishing techniques for the job:
- Vibratory Deburring – Vibratory finishing machines deburr metal components and remove sharp edges. They are also used to create a uniform, random texture over metal surfaces.
- Metal Grinding – Various grinding machines use friction to smooth out metal surfaces for different levels of finite smoothness, from coarse-textured to smooth and polished.
- Painting – Metal surface painting is very common and may be applied manually or by spray machines. Metal painting is used mostly for decorating, anti-rusting and anti-corrosion. Pre-surface treatment is often needed to get the best results from paint. As on any other surface, metal paint will dull in appearance over time and eventually split and peel. Therefore, periodic reapplication should be in the plans.
- Powder Coating – Powder coating applies a decorative finish similar to paint, but with more durability. The process involves melting dry plastic powder onto the metal to produce a textured, matte or glossy coating. A textured powder-coating machine is also highly effective in covering surface defects.
- Metal Plating – A chemical bath or electrostatic method that coats the surface of the substrate with a thin layer of alloy. Metal plating can improve durability, corrosion resistance and exterior appearance. Plating can also come in a range of color hues to add the extra designer’s touch.
- Anodizing – An electrochemical process that converts surfaces into decorative, durable, corrosion-resistant finishes. Used mostly for aluminum, an aluminum oxide layer is fully integrated with the underlying aluminum substrate so it won’t chip or peel. It has a porous structure that allows for secondary processes such as coloring and sealing. It’s recommended for aluminum that will be visible and exposed to the elements or friction, especially when color is needed.
Project management is another important aspect of surface finishing to consider. It’s crucial to know exactly where in the manufacturing or construction process your surface finishes should be applied. For example, sometimes it’s best to paint the metal on the job site as long as surfaces have been treated properly. Other times, it’s best for the fabricator to handle the painting, or they may choose to powder coat the metal instead.
Understanding how best to protect, preserve and beautify your architectural metal surfaces will help give you the final building results that you envision in your designs.