When it comes to picking the right Unistrut channel for your job, there’s much to consider: size requirements and limits, solid channel vs. one with holes, load bearing requirements, and strut configurations. Another key consideration for your Unistrut channel is the finish. Unistrut offers a variety of different finishes that provide protection from corrosion and enhance the aesthetic look of the channel and fittings. No matter the demands of your project, Unistrut has a finish to fit your application. But with a plethora of choices can come decision paralysis. Which finish makes the most sense for your installation? Read on for the pertinent details of each Unistrut finish. 

Pre-Galvanized (PG) 

Pre-Galvanized is the standard finish offered by Unistrut. It consists of pre-galvanized steel that is zinc coated via a hot dip process. Steel strip from a coil is fed through a continuous zinc coater which cleans, fluxes, and coats the steel with molten zinc. After cooling, the steel is recoiled. This coating is offered on Unistrut channel and tubing and is a well-proven, time-tested performer for indoor and outdoor applications. 

When to Use:

• Environments where weather and humidity are a factor
• PG finish is relatively inexpensive, making it a cost-effective option for many applications
• Indoor or Outdoor use

When to Avoid:

• Not ideal for severe corrosion applications (try Stainless Steel instead)
• Not weldable

Electroplated Zinc (EG) 

Electroplated Zinc is the most basic finish, and it provides a thin layer of zinc on the surface. In the electroplating process, the part to be zinc coated is immersed in a solution of zinc ions. An electric current causes the zinc to be deposited on the part. 

When to Use:

• The unique zinc coating will protect against scratches and cut edges.
• Suitable for indoor or dry environments.

When to Avoid:

• May corrode in humid or damp areas.

Perma-Gold (ZD) 

Perma-Gold or ZD finish is most commonly found in electrical applications, manufacturing plants, and electrical sensitive areas such as Data Centers. Very similar to the EG (electroplated zinc) process, ZD finish has a distinctive yellow color. 

When to Use:

• The unique zinc coating will protect against scratches and cut edges.
• Manufacturing process decreases the risk of a zinc coating damaging nearby electronic devices.

When to Avoid:

• Not ideal for severe corrosion applications (try Stainless Steel instead).
• Not weldable.

Perma-Green III (GR) 

Almost as commonly used as Pre-Galvanized, Perma-Green offers a decent amount of protection against humidity, weather, and chemical/corrosive agents. It provides superior resistance to chalking, checking, and fading, and is less vulnerable to common acidic atmospheres, solvents, and alkalis. Unistrut’s Perma-Green III finish is the result of an environmentally neutral process that virtually eliminates the toxic metals commonly found in competitive plant-based finishes. 

When to Use:

• Standard indoor or light industrial applications
• Medical settings, like hospitals

When to Avoid:

• Outdoor and coastal applications, specifically harsh environments

Plain (PL) 

As the name suggests, this finish is simply plain carbon steel with only a light coating of oil to help prevent rust. Channel retains the oiled surface that is applied to the raw steel during the rolling process, and fittings have the original oiled surface of the coil or strip steel material. Although carbon steel will rust over time, it can be hot dipped, powder coated, or painted. This finish is a great choice for manufacturing since the desired finish can be applied to the completed product. 

When to Use:

• OEM manufacturing or when welding is needed.
• Retail, Universities, or other applications where the channel can be painted to match the interior space.

When to Avoid:

• Outdoor environments or applications with a lot of moisture or corrosive elements.

Hot Dip Galvanized (HG) 

Similar to PG (pre-galvanized), the Hot Dip Galvanized finish has a thicker, more robust layer of galvanizing. In hot dip galvanizing, the finished part is immersed in a bath of molten zinc. This method results in complete zinc coverage and a thicker coating than pre-galvanized or plated zinc. 

When to Use:

• Outdoor applications, moderate corrosive environments with a lot of moisture.
• Provides much better protection than Pre-Galvanized (PG), and more affordable than Stainless Steel channel.

When to Avoid:

• Not ideal for applications involving welding (toxic fumes), or severe corrosive environments such as saltwater climates.
• Not as widely available as other finishes such as PG, so longer lead times sometimes result.

Stainless Steel (304 SS or 316 ST) 

Stainless Steel Unistrut is a high-quality, corrosion-resistant material that offers the longest anticipated service life of any steel channel or fittings in the Unistrut family. Ideal for outdoor and highly-corrosive applications, Unistrut’s stainless steel products will endure the harshest of environments. It offers five times the corrosion protection over Hot Dip Galvanized Unistrut. Aside from standard Stainless Steel, Unistrut also offers a Food Grade stainless steel product line. Food Grade Strut is a patented system for mounting pipe and conduit in sanitary food processing applications. It is ideal for pharmaceutical, food processing, and other cleanroom applications. 

When to Use:

• Wastewater treatment plants
• Oil and gas processing facilities and refineries
• Any outdoor application in high salinity environments (shipyards, offshore drilling platforms, etc.)
• Power plants
• Industrial rooftops
• Pharmaceutical and clean rooms
• Chemical plants
• Food processing and breweries

When to Avoid:

• Projects where severe corrosion resistance is not needed.

Aluminum (EA) 

Unistrut Metal Framing products are available in extruded aluminum. Aluminum Unistrut is a lightweight alternative to steel Unistrut, however, reduced self-weight means reduced performance. When lightweight material is necessary, Aluminum is the perfect choice. 

When to Use:

• Solar racking
• Fire truck and emergency vehicle OEMs
• Passenger bus seating manufacturers
• Catwalks and Roofwalks
• Rooftop pipe/duct supports

When to Avoid:

• When the strut system needs to do heavy lifting - aluminum Unistrut uses a 33% reduction factor for all beam and column loading.

Unistrut Defender (DF) 

Unistrut Defender is a proprietary, corrosion-resistant finish by Unistrut. It is three times more corrosion-resistant than Hot Dip Galvanized products and has self-healing properties to mitigate any cuts or scratches in the field. Due to its unique features, the Defender finish results in particularly low-maintenance products, reducing the need to repair or replace over time. 

When to Use:

• Outdoor and coastal applications, specifically harsh environments.
• Compatible with all HG Unistrut fittings and hardware.

When to Avoid:

• Not compatible with Stainless Steel Unistrut fittings and hardware.

Give us a call to get started on your Unistrut project. Whether you want to walk through your finish choices, or get straight to work, our team is happy to help.