Collar rot is the formation of rust around the post at the point of contact with the concrete slab.

ASTM terminology (G5) defines corrosion as:

“The chemical or electrochemical reaction between a material, usually metal, and its environment that produces a deterioration of the material and its properties.”

For steel posts embedded in concrete, corrosion results in the formation of rust.

Steel (posts) in concrete is initially in a non-corroding, passive condition. However, because fence posts protrude through concrete slabs, both materials are subjected to environmental effects.

Where seawater or deicing salts (such as rainwater) are present, chlorides penetrate the concrete and disrupt the passive layer protecting the fence post — causing it to rust and pit.

Techniques exist to isolate such posts from these damaging environments and reduce atmospheric corrosion. One option is to change the material from which the posts are made. Stainless steel is one such example, but very expensive.

Another method is to use a heavier (thicker wall) grade of steel. However, this only delays the inevitable and also increases costs significantly.

All of these techniques are unnecessary if you simply use a Post Collar Protector.

The Post Collar Protector is made from Nylon (Polyamide) — a plastic material that is very durable, yet flexible enough to form a protective barrier around the steel post and shield it from environmental exposure.

Nylon quick facts:
• Excellent resistance (no attack) to:
• Oils, solvents, dilute acids
• Formaldehyde, alcohols, bases, and THF
• Tough, strong, and impact resistant
• Maximum temperature: 99°C
• Minimum temperature: -70°C
• Melting point: 216°C
• Tensile strength: 5,800 psi
• Hardness: Rockwell R92
• UV resistance: Excellent (in black)
• Specific gravity: 1.3