Selecting Unistrut Channel Finishes for Optimal Corrosion Resistance

For dry indoor settings and certain fabrication needs, Unistrut offers standard finishes that prioritize workability or light-duty protection.

• Plain : Mill oil is retained and no additional coating is applied. The finish requires minimal preparation before welding, making it suitable for custom structures that will be welded on site.
• Perma-Green III : A high-performance coating designed to resist fading, chalking and cracking. It contains no toxic metals and offers resistance to acidic environments, solvents and alkaline substances, positioning it for indoor and light industrial use.

When applications move outdoors or into damp settings, corrosion protection becomes the primary consideration. Unistrut provides two main zinc coating options.

Pre-galvanized (PG) steel is produced by feeding steel strip through a continuous line and dipping it into molten zinc. The process is established and economical, and the G90 standard is generally sufficient for most indoor and outdoor applications.

Hot-dip galvanized (HG) parts are immersed whole in a zinc bath, producing a thicker and more complete zinc layer. Before the introduction of Unistrut Defender, it was the brand’s strongest corrosion option and remains suited to heavy industrial environments with high corrosion demands.

Historically, engineers facing highly corrosive environments had to choose between expensive stainless steel and galvanized steel with limited performance. Unistrut Defender was developed to address that gap.

The product line uses a dual coating technology that meets ASTM A1046 and A1059 standards. Testing cited by the manufacturer indicates corrosion resistance three times that of conventional hot-dip galvanized products. It is positioned as offering corrosion performance close to stainless steel while maintaining a lower-cost profile for projects that require long service life.